Date: Wed, 29 Apr 09 00:00:27 GMT Subject: astro-ph daily 44 new + 2 crosses received by eprepget ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ Send any comments regarding submissions directly to submitter. ------------------------------------------------------------------------------ Archives at http://arxiv.org/ To unsubscribe, e-mail To: astro-ph@arXiv.org, Subject: cancel ------------------------------------------------------------------------------ received by eprepget from Mon 27 Apr 09 20:00:01 GMT to Tue 28 Apr 09 20:00:01 GMT ------------------------------------------------------------------------------ \\ arXiv:0904.4247 Date: Mon, 27 Apr 2009 20:00:13 GMT (60kb) Title: Angular Momentum Transfer and Lack of Fragmentation in Self-Gravitating Accretion Flows Authors: Mitchell Begelman and Isaac Shlosman (JILA/CU Boulder) Categories: astro-ph.CO Comments: 5 pp., 1 figures, submitted to the Astrophysical Journal Letters \\ Rapid inflows associated with early galaxy formation lead to the accumulation of self-gravitating gas in the central regions of proto-galaxies. Such gas accumulations are prone to non-axisymmetric instabilities, as in the well-known Maclaurin sequence of rotating ellipsoids, which are accompanied by a catastrophic loss of angular momentum. Self-gravitating gas is also intuitively associated with star formation. However, recent numerical simulations of the infall process display highly turbulent flows, which do not fragment. We propose that the angular momentum transfer process, which enables the inflow, also suppresses fragmentation. We argue that inefficient angular momentum loss by the gas leads to decay of the turbulence, which in turn triggers global instabilities in the gas and renewed turbulence driving. We show that a flow regulated in this way is stable against fragmentation, whilst staying close to the instability threshold for bar formation -- thick self-gravitating disks are prone to global instabilities before they become unstable locally. On smaller scales, the fraction of gravitationally unstable matter swept up by shocks in such a flow is a small and decreasing function of the Mach number. We therefore conclude, counterintuitively, that gas able to cool down to a small fraction of its virial temperature will not fragment as it collapses. This provides a venue for supermassive black holes to form via direct infall of gas into galactic nuclei, without the intermediary stage of forming a star cluster. Some black holes could have formed or grown extensively in massive dark matter halos at relatively low redshifts. \\ ( http://arxiv.org/abs/0904.4247 , 60kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4250 Date: Mon, 27 Apr 2009 20:00:23 GMT (1195kb) Title: The Structures of Distant Galaxies - II: Diverse Galaxy Structures and Local Environments at z = 4-6; Implications for Early Galaxy Assembly Authors: Christopher J. Conselice, Jessica Arnold Categories: astro-ph.CO astro-ph.GA Comments: MNRAS, accepted, 28 pages, 20 figures \\ We present an analysis of the structures, sizes, star formation rates, and local environmental properties of galaxies at z~4-6, utilising deep Hubble Space Telescope imaging of the Hubble Ultra Deep Field. The galaxies we study are selected with the Lyman-break drop-out technique, using galaxies which are B-,V-, and i-drops, which effectively selects UV bright starbursting galaxies between z=4 and z=6. Our primary observational finding is that starbursting galaxies at z>4 have a diversity in structure, with roughly 30% appearing distorted and asymmetric, while the majority are smooth and apparently undisturbed systems. We utilize several methods to compute the inferred assembly rates for these distorted early galaxies including utilising the CAS system and pair counts. Overall, we find a similar fraction of galaxies which are in pairs as the fraction which have a distorted structure. Using the CAS methodology, and our best-estimate for merger time-scales, we find that the total number of inferred effective mergers for M_{*} > 10^9-10 M_sol galaxies at z<6 is N_m = 4.2^{+4.1}_{-1.4}. The more common symmetrical systems display a remarkable scaling relation between the concentration of light and their half-light radii, revealing the earliest known galaxy scaling relationship, and demonstrating that some galaxies at z>4 are likely in a relaxed state. Systems which are asymmetric do not display a correlation between size and half-light radii, and are generally larger than the symmetric smooth systems. The time-scale for the formation of these smooth systems is 0.5-1 Gyr, suggesting that most of these galaxies are formed through coordinated very rapid gas collapses and star formation over a size of 1-2 kpc, or from merger events at z > 10. (Abridged) \\ ( http://arxiv.org/abs/0904.4250 , 1195kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4251 Date: Mon, 27 Apr 2009 20:01:06 GMT (120kb) Title: Angular Momentum Transport in Extended Galactic Disks Authors: C.P. McNally, J. Wadsley, H.M.P. Couchman Categories: astro-ph.GA Comments: ApJ Letters accepted, 5 pages, 3 figure \\ We demonstrate a significant difference in the angular momentum transport properties of galactic disks between regions in which the interstellar medium is single phase or two phase. Our study is motivated by observations of HI in extended galactic disks which indicate velocity dispersions of nonthermal origin, suggesting that turbulence in the gas may be contributing significantly to the observed dispersion. To address this, we have implemented a shearing-box framework within the FLASH code. The new code was used to perform local simulations of galactic disks that incorporate differential rotation, self-gravity, vertical stratification, hydrodynamics and cooling. These simulations explore plausible mechanisms for driving turbulent motions via the thermal and self-gravitational instabilities coupling to differential rotation. Where a two-phase medium develops, gravitational angular momentum transporting stresses are much greater, creating a possible mechanism for transferring energy from galactic rotation to turbulence. In simulations where the disk conditions do not trigger the formation of a two-phase medium, it is found that perturbations to the flow damp without leading to a sustained mechanism for driving turbulence. The differing angular momentum transport properties of the single- and two-phase regimes of the disk suggest that a significant, dynamically motivated division can be drawn between the two, even when this division occurs far outside the star formation cutoff in a galactic disk. \\ ( http://arxiv.org/abs/0904.4251 , 120kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4252 Date: Mon, 27 Apr 2009 20:02:27 GMT (754kb,D) Title: Resolved stellar mass maps of galaxies. I: method and implications for global mass estimates Authors: Stefano Zibetti (1), Stephane Charlot (2), Hans-Walter Rix (1) ((1) MPIA Heidelberg, (2) IAP Paris) Categories: astro-ph.CO astro-ph.IM Comments: Submitted to MNRAS on April 1st 2009. 20 pages, 13 figures (see http://www.mpia.de/homes/zibetti/mass_maps_MN_ed.pdf for full resolution) \\ (Abridged) We introduce a novel technique to construct spatially resolved maps of stellar mass surface density in galaxies based on optical and near IR imaging. We use optical/NIR colour(s) to infer effective stellar mass-to-light ratios (M/L) at each pixel, which are then multiplied by the surface brightness to obtain the local stellar surface mass density. We build look-up tables to express M/L as a function of colour(s) by marginalizing over a Monte Carlo library of 50,000 stellar population synthesis (SPS) models by Charlot & Bruzual (2007), which include a revised prescription for the TP-AGB stellar evolutionary phase, with a wide range of dust exinctions. In order to extract reliable flux and colour information at any position in the galaxy, we perform a median adaptive smoothing of the images that preserves the highest possible spatial resolution. As the most practical and robust, and hence fiducial method, we express the M/L in the H band as a function of (g-i) and (i-H). Stellar mass maps computed in this way have a typical accuracy of 30 per cent or less at any given pixel, determined from the scatter in the models. We compare maps obtained with our fiducial method with those derived using other combinations of bandpasses and the old BC03 TP-AGB prescription. Finally, we compare total stellar mass estimates obtained by integrating resolved mass maps with those obtained with unresolved photometry. In galaxies with evident dust lanes, unresolved estimates may miss up to 40 per cent of the total stellar mass because dusty regions are strongly under-represented in the luminous fluxes. \\ ( http://arxiv.org/abs/0904.4252 , 754kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4254 Date: Mon, 27 Apr 2009 20:08:09 GMT (371kb) Title: The 21 cm Forest as a Probe of the Reionization and the Temperature of the Intergalactic Medium Authors: Yidong Xu, Xuelei Chen, Zuhui Fan, Hy Trac, Renyue Cen Categories: astro-ph.CO Comments: 26pages, 15 figures, submitted to ApJ \\ Using high redshift radio sources as background, the 21cm forest observations probe the neutral hydrogen absorption signatures of early structures along the lines of sight. Directly sensitive to the spin temperature of the hydrogen atoms, it complements the 21cm tomography observations, and provides information on the temperature as well as the ionization state of the intergalactic medium (IGM). We use a radiative transfer simulation to investigate the 21cm forest signals during the epoch of reionization. We first check whether the equivalent width (EW) can be a representative indicator of the ionization and thermal state of the IGM, and find that the optical depth and EW are good representation of the reionization process. The features selected by their relative optical depth are excellent tracers of ionization fields, and the features selected by their absolute optical depth are very sensitive to the IGM temperature, so the IGM temperature information could potentially be extracted from 21cm forest observation, thus breaking a degeneracy in 21cm tomographic observation. With the tool of EW statistics, we predict some observational consequences for 21cm forest. From the distributions of EWs and the number evolution of absorbers and leakers with different EWs, we see clearly the cosmological evolution of ionization states of the IGM. The number density of potentially observable features decreases rapidly with increasing gas temperature. Finally we discuss the requirements of the background radio sources for such observations, and find that signals with equivalent widths larger than 1kHz are hopeful to be detected. \\ ( http://arxiv.org/abs/0904.4254 , 371kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4256 Date: Mon, 27 Apr 2009 22:47:52 GMT (1077kb) Title: Doublets and Double Peaks: Late-Time [O I] 6300, 6364 Line Profiles of Stripped-Envelope, Core-Collapse Supernovae Authors: D. Milisavljevic, R. Fesen, C. Gerardy, R. Kirshner, P. Challis Categories: astro-ph.CO Comments: 15 pages, 10 figures \\ (Abridged) New optical spectra of SN 2007gr, SN 2007rz, SN 2007uy, SN 2008ax, and SN 2008bo obtained 2-12 months after outburst are presented and compared to 15 other stripped-envelope core-collapse supernovae (CCSN) with published late-time spectra as part of an investigation of CCSN exhibiting double-peaked [O I] 6300, 6364 line profiles. This sample of 20 SN shows a variety of [O I] 6300, 6364 line profiles which we categorize into two types: (1) those showing two conspicuous emission peaks nearly symmetrically centered on either side of 6300 Angstroms with a wavelength separation near 64 Angstroms, and (2) those showing asymmetric [O I] line profiles consisting of a pronounced emission peak near 6300 Angstroms plus one or more blueshifted emission peaks. We conclude that although aspherically distributed ejecta may be present in these CCSN, neither [O I] double-peaked profile type is necessarily the signature of emission from front and rear faces of ejecta arranged in a toroidal disk or elongated shell geometry as previously suggested. We find that asymmetric double-peaked profiles, if interpreted to originate from tori, require the unexpected situation where the centers of expansion are systematically displaced toward the observer at velocities up to 2000 km/s, whereas symmetric double-peaked profiles may simply arise from the doublet line nature of [O I] seen under optically thick conditions leading to a 6300:6364 intensity ratio close to one. While the underlying cause of the observed predominance (18 out of 20) of blueshifted emission peaks is unclear, it may be due to internal scattering or dust obscuration of emission from far side ejecta. \\ ( http://arxiv.org/abs/0904.4256 , 1077kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4257 Date: Mon, 27 Apr 2009 20:18:43 GMT (37kb) Title: Primordial Non-Gaussianity from LAMOST Surveys Authors: Yan Gong, Xin Wang, Zheng Zheng, Xuelei Chen Categories: astro-ph.CO Comments: 8 pages, 2 figures, submitted to Research in Astronomy and Astrophysics \\ The primordial non-Gaussianity (PNG) in matter density perturbation is a very powerful probe of the physics of the very early Universe. The local PNG can induce a distinct scale-dependent bias on the large scale structure distribution of galaxies and quasars, which could be used for constraining it. We study the detection limits on PNG from the surveys of the LAMOST telescope. The cases of the main galaxy survey, the luminous red galaxy (LRG) survey, and the quasar survey of different magnitude limits are considered. We find that the MAIN1 sample (i.e. the main galaxy survey with one magnitude deeper than the SDSS main galaxy survey, or r<18.8) could only provide very weak constraint on PNG. For the MAIN2 sample (r<19.8) and the LRG survey, the 2\sigma (95.5%) limit on the PNG parameter f_{NL} are |f_{NL}|<145 and |f_{NL}|<114 respectively, comparable to the current limit from cosmic microwave background (CMB) data. The quasar survey could provide much more stringent constraint, and we find that the 2\sigma limit for |f_{NL}| is between 50 and 103, depending on the magnitude limit of the survey. With Planck-like priors on cosmological parameters, the quasar survey with g<21.65 would improve the constraints to |f_{NL}|<43 (2\sigma). We also discuss the possibility of further tightening the constraint by using the relative bias method proposed by Seljak(2008). \\ ( http://arxiv.org/abs/0904.4257 , 37kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4261 Date: Tue, 28 Apr 2009 11:19:47 GMT (229kb) Title: The H alpha Galaxy Survey VII. The spatial distribution of star formation within disks and bulges Authors: P. A. James, C. F. Bretherton, J. H. Knapen Categories: astro-ph.CO Comments: 15 pages, accepted for publication by Astronomy and Astrophysics. See also arXiv:0904.4263 \\ We analyse the current build-up of stellar mass within the disks and bulges of nearby galaxies through a comparison of the spatial distributions of forming and old stellar populations. H alpha and R-band imaging are used to determine the distributions of young and old stellar populations in 313 S0a - Im field galaxies out to 40 Mpc. Concentration indices and mean normalised light profiles are calculated as a function of galaxy type and bar classification. The mean profiles and concentration indices show a strong and smooth dependence on galaxy type. Apart from a central deficit due to bulge/bar light in some galaxy types, mean H alpha and R-band profiles are very similar. Mean profiles within a given type are remarkably constant even given wide ranges in galaxy luminosity and size. SBc, SBbc and particularly SBb galaxies have profiles that are markedly different from those of unbarred galaxies. H alpha emission from SBb galaxies is studied in detail; virtually all show resolved central components and concentrations of star formation at or just outside the bar-end radius. In these galaxies, star formation has the same radial distribution as R-band light, i.e. stellar mass is building at approximately constant morphology, with no strong evidence for outer truncation or inside-out disk formation. (Abridged.) \\ ( http://arxiv.org/abs/0904.4261 , 229kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4263 Date: Mon, 27 Apr 2009 20:23:26 GMT (1319kb) Title: The H alpha Galaxy Survey. VIII. Close companions and interactions, and the definition of starbursts Authors: Johan H. Knapen (IAC) and Philip A. James (LJMU) Categories: astro-ph.CO Comments: ApJ, in press (June 20, 2009 issue). With HaGS Paper VII (James, Bretherton, and Knapen 2009, arXiv:0904.4261), this paper concludes the H alpha Galaxy Survey \\ (Shortened) We consider the massive star formation properties, radial profiles, and atomic gas masses of those galaxies in our H alpha Galaxy Survey, a representative sample of the local Universe of 327 disk galaxies, that have close companion galaxies, in comparison with a matched control sample of galaxies without companions. We find that the presence of a close companion raises the star formation rate by a factor of just under two, while increasing hardly at all the equivalent width of the H alpha emission. This means that although statistically galaxies with close companions form stars at a higher rate, they do this over extended periods of time, and not as bursts. We find no significant increase in the central concentration of the star formation as a result of the presence of a close companion. The fraction of truly interacting or merging galaxies is very small in the local Universe, at around 2%, and possibly 4% of bright galaxies. Most of these interacting galaxies currently have unremarkable star formation properties. We also study the properties of the Survey galaxies with the most extreme values for star formation indicators such as rate, equivalent width, star formation rate per area, and gas depletion timescale. We find that each of these indicators favors a different subset of galaxies, and use this information to discuss critically the possible definitions of the term starburst to describe galaxies with enhanced star formation activity. We conclude that no one starburst definition can be devised which is objective and generally discriminant. Unless one restricts the use of the term "starburst" to a very small number of galaxies, the term will continue to be used for a heterogeneous and wide-ranging collection of objects with no physical basis for their classification as starburst. \\ ( http://arxiv.org/abs/0904.4263 , 1319kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4266 Date: Mon, 27 Apr 2009 20:40:44 GMT (23kb) Title: Rayleigh Adjustment of Narrow Barriers in Protoplanetary Disks Authors: Chao-Chin Yang (Univ. Illinois at Urbana & AMNH), Kristen Menou (Columbia Univ.) Categories: astro-ph.EP Comments: 11 pages, 2 figures, submitted to ApJL (version reflecting various referee comments) \\ Sharp density features in protoplanetary disks, for instance at the edge of a magnetically dead zone, have recently been proposed as effective barriers to slow down or even stop the problematically fast migration of planetary cores into their central star. Density features on a radial scale approaching the disk vertical scale height might not exist, however, since they could be Rayleigh (or more generally Solberg-Hoiland) unstable. Stability must be checked explicitly in one-dimensional viscous accretion disk models because these instabilities are artificially eliminated in the process of reducing the full set of axisymmetric equations. The disk thermodynamics, via the entropy stratification, and its vertical structure also influence stability when sharp density features are present. We propose the concept of Rayleigh adjustment for viscous disk models: any density feature that violates Rayleigh stability (or its generalization) should be diffused radially by hydrodynamical turbulence on a dynamical time, approaching marginal stability in a quasi-continuous manner. \\ ( http://arxiv.org/abs/0904.4266 , 23kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4268 Date: Mon, 27 Apr 2009 22:06:00 GMT (17kb) Title: Observational Consequences of Topological Currents in Neutron Stars Authors: James Charbonneau Categories: astro-ph.HE Comments: 4 pages, prepared for the proceedings of the the 24th Lake Louise Winter Institute \\ We argue that topological vector currents may be the source of many phenomena in neutron stars: kicks, jets, toroidal fields and magnetic helicity. Topological vector currents exist because of the P-symmetry violation of the weak interaction. Kicks and helicity are both objects that transform as pseudovectors and thus require P-symmetry violation to manifest themselves. This symmetry argument is supported numerically; topological currents provide transfer enough momentum to describe even the largest of kicks and can generate large toroidal fields that create helicity. An observational signature of currents is a faint left circular polarization in the X-rays in the wake of the neutron star that may require high precision polarimetry to see. \\ ( http://arxiv.org/abs/0904.4268 , 17kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4276 Date: Mon, 27 Apr 2009 22:39:43 GMT (59kb) Title: Correlations between Ultrahigh Energy Cosmic Rays and Infrared-Luminous Galaxies Authors: Glennys R. Farrar, Andreas A. Berlind and Ingyin Zaw Categories: astro-ph.HE Comments: 4 pp \\ We confirm the UHECR horizon established by the Pierre Auger Observatory using the heterogeneous Veron-Cetty Veron (VCV) catalog of AGNs, by performing a redshift-angle-IR luminosity scan using PSCz galaxies having infrared luminosity greater than 10^{10}L_sun. The strongest correlation -- for L_ir > 10^{10.5}L_sun, maximum separation 2.1 deg, and z_max = 0.016 -- arises in fewer than 0.3% of scans with isotropic source directions. Since the PSCz catalog is complete and volume-limited for these parameters, this shows that the UHECR horizon discovered by Auger is not an artifact of the incompleteness and other idosyncracies of the VCV catalog. The strength of the correlation between UHECRs and the nearby highest-IR-luminosity PSCz galaxies is stronger than in about 90% percent of trials with scrambled luminosity assignments for the PSCz galaxies. If confirmed by future data, this result would indicate that the sources of UHECRs are more strongly associated with luminous IR galaxies than with ordinary, lower IR luminosity galaxies. \\ ( http://arxiv.org/abs/0904.4276 , 59kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4277 Date: Mon, 27 Apr 2009 22:45:07 GMT (1483kb) Title: Correlations between Ultrahigh Energy Cosmic Rays and AGNs Authors: Glennys R. Farrar, Ingyin Zaw and Andreas A. Berlind Categories: astro-ph.HE \\ We investigate several aspects of the correlations reported by the Pierre Auger Observatory between the highest energy cosmic rays (UHECRs) and galaxies in the Veron-Cetty Veron (VCV) catalog of AGNs. First, we quantify the extent of the inhomogeneity and impurity of the VCV catalog. Second, we determine how the correlation between the highest energy Auger UHECRs and VCV galaxies is modified when only optically-identified AGNs are used. Finally, we measure the correlation between the published Auger UHECRs and the distribution of matter. Our most important finding is that the correlation between UHECRs and AGNs is too strong to be explained purely by AGNs tracing the large scale distribution of matter, indicating that (barring the correlation being a statistical fluke) some substantial fraction of UHECRs are produced by AGNs. We also find that once we take into account the heavy oversampling of the VCV catalog in the Virgo region, the lack of UHECR events from that region is not incompatible with UHECR having AGN sources. \\ ( http://arxiv.org/abs/0904.4277 , 1483kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4278 Date: Mon, 27 Apr 2009 23:49:15 GMT (324kb) Title: Mid-IR observations of circumstellar disks -- Part III: A mixed sample of PMS stars and Vega-type objects Authors: O. Schuetz (1), G. Meeus (2), M. F. Sterzik (1) and E. Peeters (3,4,5) ((1) European Southern Observatory, Chile; (2) Astrophysikalisches Institut Potsdam, Germany; (3) NASA Ames Research Center, USA; (4) SETI Institute, USA; (5) The University of Western Ontario, Canada) Categories: astro-ph.SR Comments: Accepted for publication in A&A \\ We present new mid-infrared spectra for a sample of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars and 5 Vega type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the beta Pic moving group (HD 155555, HD 181296 and HD 319139). PAH bands are observed towards the T Tauri star HD 34700 and the Herbig Ae star PDS 144 N. For HD 34700, the band profiles indicate processed PAHs. The spectrum of the Vega-type object eta Corvi (HD 109085), for which a resolved disk at sub-mm wavelengths is known, is entirely stellar between 8--13 micron. Similarly, no indication for circumstellar matter at mid-infrared wavelengths is found towards the Vega-like stars HD 3003, HD 80951, HD 181296 and, surprisingly, the T Tauri system HD 155555. The silicate emission features of the remaining eight sources are modelled with a mixture of silicates of different grain sizes and composition. Unprocessed dust dominates FU Ori, HD 143006 and CD-43 344. Large amorphous grains are the main dust component around HD 190073, HD 319139, KK Oph and PDS 144 S. Both small grains and crystalline dust is found for the Vega-type HD 123356, with a dominance of small amorphous grains. We show that the infrared emission of the binary HD 123356 is dominated by its late-type secondary, but optical spectroscopy is still required to confirm the age of the system and the spectral class of the companion. For most targets this is their first mid-infrared spectroscopic observation. We investigate trends between stellar, disk and silicate properties and confirm correlations of previous studies. Several objects present an exciting potential for follow-up high-resolution disk studies. \\ ( http://arxiv.org/abs/0904.4278 , 324kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4280 Date: Mon, 27 Apr 2009 23:23:58 GMT (35kb) Title: Early Fermi Gamma-ray Space Telescope Observations of the Quasar 3C 454.3 Authors: Fermi/LAT Collaboration: A. A. Abdo, et al Categories: astro-ph.HE astro-ph.CO Comments: Accepted by the Astrophysical Journal; corresponding authors: Greg Madejski (madejski@slac.stanford.edu) and Benoit Lott (lott@cenbg.in2p3.fr) \\ This is the first report of Fermi Gamma-ray Space Telescope observations of the quasar 3C 454.3, which has been undergoing pronounced long-term outbursts since 2000. The data from the Large Area Telescope (LAT), covering 2008 July 7 - October 6, indicate strong, highly variable gamma-ray emission with an average flux of ~3 x 10^{-6} photons cm^{-2} s^{-1}, for energies above 100 MeV. The gamma-ray flux is variable, with strong, distinct, symmetrically-shaped flares for which the flux increases by a factor of several on a time scale of about three days. This variability indicates a compact emission region, and the requirement that the source is optically thin to pair-production implies relativistic beaming with Doppler factor delta > 8, consistent with the values inferred from VLBI observations of superluminal expansion (delta ~ 25). The observed gamma-ray spectrum is not consistent with a simple power-law, but instead steepens strongly above ~2 GeV, and is well described by a broken power-law with photon indices of ~2.3 and ~3.5 below and above the break, respectively. This is the first direct observation of a break in the spectrum of a high luminosity blazar above 100 MeV, and it is likely direct evidence for an intrinsic break in the energy distribution of the radiating particles. Alternatively, the spectral softening above 2 GeV could be due to gamma-ray absorption via photon-photon pair production on the soft X-ray photon field of the host AGN, but such an interpretation would require the dissipation region to be located very close (less than 100 gravitational radii) to the black hole, which would be inconsistent with the X-ray spectrum of the source. \\ ( http://arxiv.org/abs/0904.4280 , 35kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4287 Date: Tue, 28 Apr 2009 00:46:09 GMT (849kb) Title: Newly Identified Star Clusters in M33. II. Radial HST/ACS Fields Authors: Izaskun San Roman, Ata Sarajedini, Donald R. Garnett, and Jon A. Holtzman Categories: astro-ph.GA astro-ph.SR Comments: 28 pages, 12 figures, accepted for publication in The Astrophysical Journal \\ We present integrated photometry and color-magnitude diagrams for 161 star clusters in M33, of which 115 were previously uncataloged, using the Advanced Camera For Surveys Wide Field Channel onboard the Hubble Space Telescope. The integrated V-band magnitudes of these clusters range from Mv~-9 to as faint as Mv~-4, extending the depth of the existing M33 cluster catalogs by ~1 mag. Comparisons of theoretical isochrones to the color-magnitude diagrams using the Padova models yield ages for 148 of these star clusters. The ages range from Log (t)~7.0 to Log (t)~9.0. Our color-magnitude diagrams are not sensitive to clusters older than ~1 Gyr. We find that the variation of the clusters' integrated colors and absolute magnitudes with age is consistent with the predictions of simple stellar population models. These same models suggest that the masses of the clusters in our sample range from 5x10^3 to 5x10^4 *Msun. \\ ( http://arxiv.org/abs/0904.4287 , 849kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4290 Date: Tue, 28 Apr 2009 01:21:07 GMT (293kb) Title: RR Lyrae Variables in Two Fields in the Spheroid of M31 Authors: Ata Sarajedini, Conor L. Mancone, Tod R. Lauer, Alan Dressler, Wendy Freedman, S. C. Trager, Carl Grillmair, and Kenneth J. Mighell Categories: astro-ph.GA astro-ph.SR Comments: 54 pages, 14 figures, accepted for publication in The Astronomical Journal, only the first pages of Tables 2 and 3 as well as Fig. 4 are shown \\ We present Hubble Space Telescope observations taken with the Advanced Camera for Surveys Wide Field Channel of two fields near M32 - between four and six kpc from the center of M31. The data cover a time baseline sufficient for the identification and characterization of 681 RR Lyrae variables of which 555 are ab-type and 126 are c-type. The mean magnitude of these stars is =25.29 +/- 0.05 where the uncertainty combines both the random and systematic errors. The location of the stars in the Bailey Diagram and the ratio of c-type RR Lyraes to all types are both closer to RR Lyraes in Oosterhoff type I globular clusters in the Milky Way as compared with Oosterhoff II clusters. The mean periods of the ab-type and c-type RR Lyraes are =0.557 +/- 0.003 and =0.327 +/- 0.003, respectively, where the uncertainties in each case represent the standard error of the mean. When the periods and amplitudes of the ab-type RR Lyraes in our sample are interpreted in terms of metallicity, we find the metallicity distribution function to be indistinguishable from a Gaussian with a peak at <[Fe/H]>=-1.50 +/- 0.02, where the quoted uncertainty is the standard error of the mean. Using a relation between RR Lyrae luminosity and metallicity along with a reddening of E(B-V) = 0.08 +/- 0.03, we find a distance modulus of (m-M)o=24.46 +/- 0.11 for M31. We examine the radial metallicity gradient in the environs of M31 using published values for the bulge and halo of M31 as well as the abundances of its dwarf spheroidal companions and globular clusters. In this context, we conclude that the RR Lyraes in our two fields are more likely to be halo objects rather than associated with the bulge or disk of M31, in spite of the fact that they are located at 4-6 kpc in projected distance from the center. \\ ( http://arxiv.org/abs/0904.4290 , 293kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4300 Date: Tue, 28 Apr 2009 04:11:48 GMT (2286kb) Title: Stochastic Nature of Gravitational Waves from Supernova Explosions with Standing Accretion Shock Instability Authors: Kei Kotake, Wakana Iwakami, Naofumi Ohnishi, and Shoichi Yamada Categories: astro-ph.HE Comments: 4 pages, 3 figures, accepted by ApJL \\ We study properties of gravitational waves based on the three-dimensional simulations, which demonstrate the neutrino-driven explosions aided by the standing accretion shock instability (SASI). Pushed by evidence supporting slow rotation prior to core-collapse, we focus on the asphericities in neutrino emissions and matter motions outside the protoneutron star. By performing a ray-tracing calculation in 3D, we estimate accurately the gravitational waveforms from anisotropic neutrino emissions. In contrast to the previous work assuming axisymmetry, we find that the gravitational waveforms vary much more stochastically because the explosion anisotropies depend sensitively on the growth of the SASI which develops chaotically in all directions. Our results show that the gravitational-wave spectrum has its peak near $\sim 100$ Hz, reflecting the SASI-induced matter overturns of $\sim O(10)$ ms. We point out that the detection of such signals, possibly visible to the LIGO-class detectors for a Galactic supernova, could be an important probe into the long-veiled explosion mechanism. \\ ( http://arxiv.org/abs/0904.4300 , 2286kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4303 Date: Tue, 28 Apr 2009 04:30:22 GMT (239kb) Title: High-Mass Star Formation in the Near and Far 3-KPC Arms Authors: J. A. Green, N. M. McClure-Griffiths, J. L. Caswell, S. P. Ellingsen, G. A. Fuller, L. Quinn and M. A. Voronkov Categories: astro-ph.GA Comments: 6 pages, 3 figures, published in ApJ letters 696, L156-158 Journal-ref: 2009ApJ...696L.156G DOI: 10.1088/0004-637X/696/2/L156 \\ We report on the presence of 6.7-GHz methanol masers, known tracers of high-mass star formation, in the 3-kpc arms of the inner Galaxy. We present 49 detections from the Methanol Multibeam Survey, the largest Galactic plane survey for 6.7-GHz methanol masers, which coincide in longitude, latitude and velocity with the recently discovered far-side 3-kpc arm and the well known near-side 3-kpc arm. The presence of these masers is significant evidence for high-mass star formation actively occurring in both 3-kpc arms. \\ ( http://arxiv.org/abs/0904.4303 , 239kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4305 Date: Tue, 28 Apr 2009 04:36:07 GMT (1069kb) Title: The origin of large peculiar motions of star-forming regions and spiral structures of our Galaxy Authors: Junichi Baba, Yoshiharu Asaki, Junichiro Makino, Makoto Miyoshi, Takayuki R. Saitoh, Keiichi Wada Categories: astro-ph.GA Comments: 11 pages, 8 figures. Submitted to ApJ \\ Recent VLBI (Very Long Baseline Interferometer) observations (Xu et al. 2006; Sato et al. 2008) determined the distances and proper motions of star-forming regions in spiral arms directly. They showed that star forming regions and young stars have large non-circular motions, as large as 30 km s-1 with complex structures. Such a large motion is incompatible with the prediction of the standard theory of stationary spiral arms. We use a high-resolution, self-consistent N-body+hydrodynamical simulation to explore how the spiral arms are formed and maintained, and how star-forming regions move. We found that arms are not stationary but transient and recurrent, as suggested in alternative theories of spiral structures. Because of this transient nature of the spiral arms, star-forming regions exhibit large and complex non-circular motions, which is consistent with the VLBI observations. Due to this large non-circular motions, a kinematically estimated gas map does not represent true spiral structures in our Galaxy. \\ ( http://arxiv.org/abs/0904.4305 , 1069kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4307 Date: Tue, 28 Apr 2009 05:21:06 GMT (74kb) Title: Chemical Composition of Extremely Metal-Poor Stars in the Sextans Dwarf Spheroidal Galaxy Authors: W. Aoki, N. Arimoto, K. Sadakane, E. Tolstoy, G. Battaglia, P. Jablonka, M. Shetrone, B. Letarte, M. Irwin, V. Hill, P. Francois, K. Venn, F. Primas, A. Helmi, A. Kaufer, M. Tafelmeyer, T. Szeifert, C. Babusiaux Categories: astro-ph.GA astro-ph.SR Comments: 15 pages, 6 figures, 6 tables, A&A, in press \\ Chemical abundances of six extremely metal-poor ([Fe/H]<-2.5) stars in the Sextans dwarf spheroidal galaxy are determined based on high resolution spectroscopy (R=40,000) with the Subaru Telescope High Dispersion Spectrograph. (1) The Fe abundances derived from the high resolution spectra are in good agreement with the metallicity estimated from the Ca triplet lines in low resolution spectra. The lack of stars with [Fe/H]=<-3 in Sextans, found by previous estimates from the Ca triplet, is confirmed by our measurements, although we note that high resolution spectroscopy for a larger sample of stars will be necessary to estimate the true fraction of stars with such low metallicity. (2) While one object shows an overabundance of Mg (similar to Galactic halo stars), the Mg/Fe ratios of the remaining five stars are similar to the solar value. This is the first time that low Mg/Fe ratios at such low metallicities have been found in a dwarf spheroidal galaxy. No evidence for over-abundances of Ca and Ti are found in these five stars, though the measurements for these elements are less certain. Possible mechanisms to produce low Mg/Fe ratios, with respect to that of Galactic halo stars, are discussed. (3) Ba is under-abundant in four objects, while the remaining two stars exhibit large and moderate excesses of this element. The abundance distribution of Ba in this galaxy is similar to that in the Galactic halo, indicating that the enrichment of heavy elements, probably by the r-process, started at metallicities [Fe/H] < -2.5, as found in the Galactic halo. \\ ( http://arxiv.org/abs/0904.4307 , 74kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4313 Date: Tue, 28 Apr 2009 16:17:53 GMT (29kb) Title: Sub-Degree Sunyaev-Zel'dovich Signal from Multi-Frequency BOOMERanG observations Authors: M. Veneziani, A. Amblard, A. Cooray, F. Piacentini, D. Pietrobon, P. Serra, P. A. R. Ade, J. J. Bock, J. R. Bond, J. Borrill, A. Boscaleri, P. Cabella, C. R. Contaldi, B. P. Crill, P. de Bernardis, G. De Gasperis, A. de Oliveira-Costa, G. De Troia, G. Di Stefano, K. M. Ganga, E. Hivon, W. C. Jones, T. S. Kisner, A. E. Lange, C. J. MacTavish, S. Masi, P. D. Mauskopf, A. Melchiorri, T. E. Montroy, P. Natoli, C. B. Netterfield, E. Pascale, G. Polenta, S. Ricciardi, G. Romeo, J. E. Ruhl, P. Santini, M. Tegmark, N. Vittorio Categories: astro-ph.CO Comments: Submitted to ApJL \\ The Sunyaev-Zel'dovich (SZ) effect is the inverse Compton-scattering of cosmic microwave background (CMB) photons by hot electrons in the intervening gas throughout the Universe. The effect has a distinct spectral signature that allows its separation from other signals in multi-frequency CMB datasets. Using CMB anisotropies measured at three frequencies by the BOOMERanG 2003 flight we constrain SZ fluctuations in the 10 arcminute to one degree angular range. Propagating errors and potential systematic effects through simulations, we obtain an overall upper limit of 15.3 uK (2 sigma) for rms SZ fluctuations in a broad bin between multipoles of of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum. When combined with other CMB anisotropy and SZ measurements, we find that the local Universe normalization of the density perturbations is sigma-8(SZ) < 0.96 at the 95% confidence level, consistent with sigma-8 determined from primordial perturbations. \\ ( http://arxiv.org/abs/0904.4313 , 29kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4319 Date: Tue, 28 Apr 2009 19:46:09 GMT (8kb) Title: Lemaitre-Tolman-Bondi cosmological models, smoothness, and positivity of the central deceleration parameter Authors: R. Ali Vanderveld, Eanna E. Flanagan, and Ira Wasserman Categories: astro-ph.CO Comments: 4 pages, no figures, revtex4 \\ We argued in a previous paper [R. A. Vanderveld et al. 2006] that negative deceleration parameters at the center of symmetry in Lemaitre-Tolman-Bondi cosmological models can only occur if the model is not smooth at the origin. Here we demonstrate explicitly the connection between non-smoothness and the failure of positivity theorems for deceleration. We also address some confusion that has arisen in the literature and respond to some recent criticisms of our arguments. \\ ( http://arxiv.org/abs/0904.4319 , 8kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4328 Date: Tue, 28 Apr 2009 08:09:50 GMT (58kb) Title: Three Spectacular HII-buried-AGN Galaxies from SDSS Authors: Yufeng Mao, Jing Wang, Jianyan Wei Categories: astro-ph.CO Comments: 15 pages, 2 figures \\ We present our analysis of the three HII-buried-AGN: SDSS J091053+333008, SDSS J121837+091324, and SDSS J153002-020415, by studying their optical spectra extracted from SDSS. The location in the BPT diagnostic diagrams of the three galaxies indicates that the narrow emission lines are mainly exited from HII regions. However, after the removal of the host galaxy's stellar emission, the emission lines display the typical feature of Narrow-line Seyfert 1-like. All of the three objects have large Eddington ratio, small black hole mass, and low star formation rate. We propose that the three galaxies are at the transit stage from the starburst-dominated phase to AGN-dominated phase. \\ ( http://arxiv.org/abs/0904.4328 , 58kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4333 Date: Tue, 28 Apr 2009 08:35:12 GMT (9kb) Title: On Some Properties of the Neutrino in The Early Universe Authors: S Mani, A Sagari, B Chakrabarti, A Bhattacharya Categories: astro-ph.CO Comments: The manuscript consists of 13 pages with no figures \\ The properties of the neutrino in the early universe have been investigated incorporating a small inhomogeneity in the mass density of the early universe. Dependence on this factor is found in studying mean free path and mass bound of neutrinos. The oscillations of neutrinos flavours have been studied by assuming a free wave packet to represent the time progression of the neutrino yielding interesting results. \\ ( http://arxiv.org/abs/0904.4333 , 9kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4353 Date: Tue, 28 Apr 2009 14:34:06 GMT (214kb) Title: Helicity at Photospheric and Chromospheric Heights Authors: S. K. Tiwari, P. Venkatakrishnan and K. Sankarasubramanian Categories: astro-ph.SR Comments: 5 pages, 1 figure, 1 table To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 2009 \\ In the solar atmosphere the twist parameter $\alpha$ has the same sign as magnetic helicity. It has been observed using photospheric vector magnetograms that negative/positive helicity is dominant in the northern/southern hemisphere of the Sun. Chromospheric features show dextral/sinistral dominance in the northern/southern hemisphere and sigmoids observed in X-rays also have a dominant sense of reverse-S/forward-S in the northern/southern hemisphere. It is of interest whether individual features have one-to-one correspondence in terms of helicity at different atmospheric heights. We use UBF \Halpha images from the Dunn Solar Telescope (DST) and other \Halpha data from Udaipur Solar Observatory and Big Bear Solar Observatory. Near-simultaneous vector magnetograms from the DST are used to establish one-to-one correspondence of helicity at photospheric and chromospheric heights. We plan to extend this investigation with more data including coronal intensities. \\ ( http://arxiv.org/abs/0904.4353 , 214kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4376 Date: Tue, 28 Apr 2009 12:25:30 GMT (173kb) Title: High-energy characteristics of the schizophrenic pulsar PSR J1846-0258 in Kes 75 Authors: L. Kuiper (1) and W. Hermsen (1,2) ((1) SRON-Utrecht, (2) University of Amsterdam) Categories: astro-ph.HE astro-ph.GA Comments: Accepted for publication in A&A \\ PSR J1846-0258 is a radio-quiet rotation-powered pulsar at the center of Supernova remnant Kes 75. It is the youngest pulsar (~723 year) of all known pulsars and slows down very predictably since its discovery in 2000. Till June 7, 2006 very stable behavior has been displayed both in the temporal and spectral domains with pulsed emission detectable by INTEGRAL IBIS ISGRI and RXTE HEXTE up to ~150 keV. Then, a dramatic brightening was detected of the pulsar during June 7-12, 2006 Chandra observations of Kes 75. This radiative event, lasting for ~55 days, was accompanied by a huge timing glitch, reported on for the first in present work. Moreover, several short magnetar-like bursts were discovered. In this work not only the time-averaged pre-outburst X-ray/soft gamma-ray characteristics are discussed in detail, but also the spectral evolution during the outburst and its relaxation phase are addressed using RXTE PCA and HEXTE and INTEGRAL IBIS ISGRI data. \\ ( http://arxiv.org/abs/0904.4376 , 173kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4377 Date: Tue, 28 Apr 2009 12:35:01 GMT (81kb) Title: Pulsed Gamma-rays from the millisecond pulsar J0030+0451 with the Fermi Large Area Telescope Authors: Fermi/LAT Collaboration Categories: astro-ph.HE astro-ph.GA Comments: Accepted for publication in the Astrophysical Journal \\ We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar PSR J0030+0451 with the Large Area Telescope (LAT) on the \emph{Fermi} Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second millisecond pulsar to be detected in gamma-rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma Ray Observatory. The spin-down power $\dot E = $ 3.5 $\times$ 10$^{33}$ ergs s$^{-1}$ is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, respectively 0.07 $\pm$ 0.01 and 0.08 $\pm$ 0.02 wide, separated by 0.44 $\pm$ 0.02 in phase. The first gamma-ray peak falls 0.15 $\pm$ 0.01 after the main radio peak. The pulse shape is similar to that of the "normal" gamma-ray pulsars. An exponentially cut-off power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 $\pm$ 1.05 $\pm$ 1.35) $\times 10^{-8}$ cm$^{-2}$ s$^{-1}$ with cut-off energy (1.7 $\pm$ 0.4 $\pm$ 0.5) GeV. Based on its parallax distance of $(300 \pm 90)$ pc, we obtain a gamma-ray efficiency $L_\gamma / \dot{E} \simeq 15%$ for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission. \\ ( http://arxiv.org/abs/0904.4377 , 81kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4381 Date: Tue, 28 Apr 2009 12:42:00 GMT (180kb) Title: Density profile and line-of-sight mass contamination of SLACS gravitational lenses Authors: Antonio C. C. Guimar\~aes and Laerte Sodr\'e Jr. (Universidade de S\~ao Paulo) Categories: astro-ph.CO Comments: 8 pages \\ We use data from 58 strong lensing events surveyed by the Sloan Lens ACS Survey to estimate the projected galaxy mass inside their Einstein radii by two independent methods: stellar dynamics and strong gravitational lensing. Four models are examined testing the galaxy-lens density profile and a possible line-of-sigh (l.o.s.) mass contamination. We test a fixed isothermal profile and a power-law with free index, both without and with contamination. For each model, a likelihood analysis is performed to find the parameters that produce the best agreement between the dynamical and lensing masses, and the parameters confidence levels. The Bayesian evidence is calculated to allow a comparison among the models. We find that there is evidence for a l.o.s. mass contamination of the order of 10%, and that the preferred density profile is close to an isothermal profile, $\rho\propto r^{-2}$. If the l.o.s. contamination is neglected, the density profile determined by a joint lensing and dynamical analysis is flatter than isothermal. \\ ( http://arxiv.org/abs/0904.4381 , 180kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4390 Date: Tue, 28 Apr 2009 13:19:16 GMT (356kb) Title: $\Lambda$CDM as privileged state of parameter space in a generic $f(R)$ gravity Authors: Shant Baghram, M. Sadegh Movahed and Sohrab Rahvar Categories: astro-ph.CO Comments: 15 pages, 16 figures \\ {\bf{CONTEXT}}: In this work we propose a modified gravity action $f(R)=(R^n-R^n_{0})^{1/n}$ with two free parameters of $n$ and $R_{0}$ and derive the dynamics of universe for this action in the Palatini formalism. {\bf {AIM}}: We do cosmological comparison of this model with observed data to find the best parameters of model in a flat universe. {\bf{METHOD}}: To constraint the free parameters of model we use SNIa type Ia data in two sets of Gold and Union sample, CMB-shift parameter, Baryon Acoustic oscillation, gas mass fraction in cluster of galaxies and large scale structure data. {\bf {RESULT}}: The best parameters from observational data results in $n=0.98^{+0.08}_{-0.08}$ and $\Omega_M = 0.25_{+0.1}^{-0.1}$ with one sigma level of confidence. This result show that $\Lambda$CDM as a special point in the parameter space is privileged by the observations. \\ ( http://arxiv.org/abs/0904.4390 , 356kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4392 Date: Tue, 28 Apr 2009 13:24:04 GMT (269kb,D) Title: Multiwavelength periodicity study of Markarian 501 Authors: Constanze Roedig, Thomas Burkart, Oliver Elbracht and Felix Spanier Categories: astro-ph.CO astro-ph.HE Comments: 9 pages, 15 figures \\ Context: Active Galactic Nuclei are highly variable emitters of electromagnetic waves from the radio to the gamma-ray regime. This variability may be periodic, which in turn could be the signature of a binary black hole. Systems of black holes are strong emitters of gravitational waves whose amplitude depends on the binary orbital parameters as the component mass, the orbital semi-major-axis and eccentricity. Aims: It is our aim to prove the existence of periodicity of the AGN Markarian 501 from several observations in different wavelengths. A simultaneous periodicity in different wavelengths provides evidence for bound binary black holes in the core of AGN. Methods: Existing data sets from observations by Whipple, SWIFT, RXTE, VERITAS and MAGIC have been analysed with the Lomb-Scargle method, the epoch folding technique and the SigSpec software. Results: Our analysis shows a 72-day period, which could not be seen in previous works due to the limited length of observations. This does not contradict a 23-day period which can be derived as a higher harmonic from the 72-day period. \\ ( http://arxiv.org/abs/0904.4392 , 269kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4394 Date: Tue, 28 Apr 2009 02:57:27 GMT (7542kb) Title: Search for Gravitational Wave Bursts from Soft Gamma Repeaters Authors: Peter Kalmus Categories: astro-ph.HE Comments: PhD thesis Report-no: LIGO-P080079-00-Z \\ We present the results of a LIGO search for short-duration gravitational waves (GW) associated with soft gamma repeater (SGR) bursts. This is the first GW search sensitive to neutron star f-modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 2004 December 27 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14 which occurred during the first year of LIGO's fifth science run. GW strain upper limits and model-dependent GW emission energy upper limits are estimated for individual bursts using a variety of simulated waveforms. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10^45 and 9x10^52 erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models. We also propose a new method which extends the initial SGR burst search, exploring the possibility that SGR sources emit similarly in GWs from burst to burst by "stacking" potential GW signals. We show that gains in GW energy sensitivity of N^{1/2} are possible, where N is the number of stacked SGR bursts. Estimated sensitivities for a mock search for GWs from the 2006 March 29 storm from SGR 1900+14 are presented for two stacking scenarios: a "fluence-weighted" scenario and a "flat" (unweighted) scenario. Finally, we present a method for calibrating gravitational wave detectors via photon actuators. The photon calibrators' nominal 2-sigma confidence error bars are currently estimated to be ~3%. They have provided a valuable check on the official calibration, uncovering problems that may otherwise have gone unnoticed. \\ ( http://arxiv.org/abs/0904.4394 , 7542kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4396 Date: Tue, 28 Apr 2009 14:12:15 GMT (188kb) Title: Constraints on neutrino masses from WMAP5 and BBN in the lepton asymmetric universe Authors: M. Shiraishi, K. Ichikawa, K. Ichiki, N. Sugiyama, M. Yamaguchi Categories: astro-ph.CO Comments: 11 pages, 7 figures, 5 tables \\ In this paper, we put constraints on neutrino properties such as mass $m_{\nu}$ and degeneracy parameters $\xi_i$ from WMAP5 data and light element abundances by using a Markov chain Monte Carlo (MCMC) approach. In order to take consistently into account the effects of the degeneracy parameters, we run the Big Bang Nucleosynthesis code for each value of $\xi_i$ and the other cosmological parameters to estimate the Helium abundance, which is then used to calculate CMB anisotropy spectra instead of treating it as a free parameter. We find that the constraint on $m_{\nu}$ is fairly robust and does not vary very much even if the lepton asymmetry is allowed, and is given by $\sum m_\nu < 1.3 eV$ (95% C.L.). \\ ( http://arxiv.org/abs/0904.4396 , 188kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4398 Date: Tue, 28 Apr 2009 14:00:15 GMT (1964kb) Title: Three-dimensional Numerical Simulations of Magnetized Winds of Solar-Like Stars Authors: A. A. Vidotto (1,2), M. Opher (2), V. Jatenco-Pereira (1), T. I. Gombosi (3) ((1) Univ. of Sao Paulo - Brazil, (2) George Mason University - USA, (3) University of Michigan - USA) Categories: astro-ph.SR Comments: Accepted for publication in the Astrophysical Journal, 12 pages, 12 figures, emulateapj. High-resolution version available at http://www.astro.iag.usp.br/~aline/papers/2009apj-solar-like.pdf \\ By means of self-consistent 3D MHD numerical simulations, we analyze magnetized solar-like stellar winds and their dependence on the plasma-beta parameter. We adopt in our simulations a heating parameter described by gamma, which is responsible for the thermal acceleration of the wind. We analyze winds with polar magnetic field intensities ranging from 1 to 20G. We show that the wind structure presents characteristics that are similar to the solar coronal wind. The steady-state magnetic field topology for all cases is similar, presenting a configuration of helmet streamer-type, with zones of closed field lines and open field lines coexisting. Higher magnetic field intensities lead to faster and hotter winds. The increase of the field intensity generates a larger dead zone in the wind, i. e., the closed loops that inhibit matter to escape from latitudes lower than ~45 degrees extend farther away from the star. The Lorentz force leads naturally to a latitude-dependent wind. We show that by increasing the density and maintaining B0=20G, the system recover back to slower and cooler winds. For a fixed gamma, we show that the key parameter in determining the wind velocity profile is the beta-parameter at the coronal base. Therefore, there is a group of magnetized flows that would present the same terminal velocity despite of its thermal and magnetic energy densities, as long as the plasma-beta parameter is the same. This degeneracy, however, can be removed if we compare other physical parameters of the wind, such as the mass-loss rate. We analyze the influence of gamma in our results and we show that it is also important in determining the wind structure. (Abridged) \\ ( http://arxiv.org/abs/0904.4398 , 1964kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4410 Date: Tue, 28 Apr 2009 14:27:42 GMT (50kb) Title: Spitzer IRS observations of k+a galaxies: A link between PAH emission properties and AGN feedback? Authors: I. G. Roseboom, S. Oliver, D. Farrah Categories: astro-ph.CO Comments: 13 pages, 3 figures, accepted for publication in ApjL \\ We have performed IRS low resolution 5-12 micron spectroscopy on a sample of galaxies selected to be at 3 distinct post-starburst evolutionary stages based on their optical spectral indices. The resulting IRS spectra show distinctive PAH emission line structures at 6.2, 7.7, 8.6 and 11.3 micron and little silicate absorption, indicative of ongoing star formation. However the PAH inter-line ratios, in particular the 11.3/6.2 micron and 7.7/6.2 micron ratio, show large variations. These variations are found to correlate with both time since the most recent starburst and AGN activity. We speculate that the evolution observed in these PAH ratios is related to an increase in AGN activity with time since star burst. \\ ( http://arxiv.org/abs/0904.4410 , 50kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4419 Date: Tue, 28 Apr 2009 15:10:50 GMT (1737kb,D) Title: Initiation of Coronal Mass Ejections in a Global Evolution Model Authors: A.R. Yeates (1), D.H. Mackay (2) ((1) Harvard-Smithsonian Center for Astrophysics, (2) University of St Andrews) Categories: astro-ph.SR Comments: 15 pages, 9 figures, accepted for publication in ApJ \\ Loss of equilibrium of magnetic flux ropes is a leading candidate for the origin of solar coronal mass ejections (CMEs). The aim of this paper is to explore to what extent this mechanism can account for the initiation of CMEs in the global context. A simplified MHD model for the global coronal magnetic field evolution in response to flux emergence and shearing by large-scale surface motions is described and motivated. Using automated algorithms for detecting flux ropes and ejections in the global magnetic model, the effects of key simulation parameters on the formation of flux ropes and the number of ejections are considered, over a 177-day period in 1999. These key parameters include the magnitude and sign of magnetic helicity emerging in active regions, and coronal diffusion. The number of flux ropes found in the simulation at any one time fluctuates between about 28 and 48, sustained by the emergence of new bipolar regions, but with no systematic dependence on the helicity of these regions. However, the emerging helicity does affect the rate of flux rope ejections, which doubles from 0.67 per day if the bipoles emerge untwisted to 1.28 per day in the run with greatest emerging twist. The number of ejections in the simulation is also increased by 20%-30% by choosing the majority sign of emerging bipole helicity in each hemisphere, or by halving the turbulent diffusivity in the corona. For reasonable parameter choices, the model produces approximately 50% of the observed CME rate. This indicates that the formation and loss of equilibrium of flux ropes may be a key element in explaining a significant fraction of observed CMEs. \\ ( http://arxiv.org/abs/0904.4419 , 1737kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4422 Date: Tue, 28 Apr 2009 19:38:41 GMT (853kb) Title: Multiwavelength Observations of LS I +61 303 with VERITAS, Swift and RXTE Authors: VERITAS Collaboration:V. A. Acciari, E. Aliu, T. Arlen, M. Bautista, M. Beilicke, W. Benbow, M. Bottcher, S. M. Bradbury, V. Bugaev, Y. Butt, Y. Butt, K. Byrum0, A. Cannon, A. Cesarini, Y. C. Chow, L. Ciupik, P. Cogan, P. Colin, W. Cui, M. Daniel, R. Dickherber, T. Ergin, A. Falcone, S. J. Fegan, J. P. Finley, P. Fortin, L. Fortson, A. Furniss, D. Gall, G. H. Gillanders, J. Grube, R. Guenette, G. Gyuk, D. Hanna, E. Hays, J. Holder, D. Horan, C. M. Hui, T. B. Humensky, P. Kaaret, N. Karlsson, D. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. LeBohec, G. Maier, A. McCann, M. McCutcheon, J. Millis, P. Moriarty, R. Mukherjee, T. Nagai, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, J. S. Perkins, M. Pohl, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, M. Stroh, S. Swordy, M. Theiling, J. A. Toner, A. Varlotta, V. V. Vassiliev, R. G. Wagner, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinsteiny, R. J. White, D. A. Williams, S. Wissely, M. Woody, B. Zitzer Categories: astro-ph.HE Comments: 30 pages, 5 figures, 2 table, Accepted for publication in The Astrophysical Journal \\ We present results from a long-term monitoring campaign on the TeV binary LSI +61 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between September 2006 and February 2008. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8 sigma (2006/2007) and 7.3 sigma (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5 to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6 sigma significance level) for TeV emission outside of the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0*10^-11 ergs cm^-2 s^-1 over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands. \\ ( http://arxiv.org/abs/0904.4422 , 853kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4423 Date: Tue, 28 Apr 2009 15:23:32 GMT (703kb) Title: Formation of sharp edges and planar areas of asteroids by polyhedral abrasion Authors: G. Domokos, A. \'A. Sipos, Gy. M. Szab\'o, P. L. V\'arkonyi Categories: astro-ph.EP Comments: 17 pages, 3 figures, accepted by Astrophysical Journal \\ While the number of asteroids with known shapes has drastically increased over the past few years, little is known on the the time-evolution of shapes and the underlying physical processes. Here we propose an averaged abrasion model based on micro-collisons, accounting for asteroids not necessarily evolving toward regular spheroids, rather (depending on the fall-back rate of ejecta) following an alternative path, thus confirming photometry-derived features, e.g. existence of large, relatively flat areas separated by edges. We show that our model is realistic, since the bulk of the collisions falls into this category. \\ ( http://arxiv.org/abs/0904.4423 , 703kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4427 Date: Tue, 28 Apr 2009 15:28:08 GMT (929kb) Title: Suzaku X-Ray Study of an Anomalous Source XSS J12270-4859 Authors: Kei Saitou, Masahiro Tsujimoto, Ken Ebisawa, Manabu Ishida Categories: astro-ph.HE Comments: 4 pages, 3 figures, accepted for publication in PASJ Letters \\ We report the results of the Suzaku X-ray observation of XSS J12270-4859, one of the hard X-ray sources in the INTEGRAL catalogue. The object has been classified as an intermediate polar (IP) by optical spectra and a putative X-ray period of ~860 s. With a 30 ks exposure of Suzaku, we obtained a well-exposed spectrum in the 0.2-70 keV band. We conclude against the previous IP classification based on the lack of Fe Ka emission features in the spectrum and the failure to confirm the previously reported X-ray period. Instead, the X-ray light curve is filled with exotic phenomena, including repetitive flares lasting ~100 s, occasional dips with no apparent periodicities, spectral hardening after some flares, and bimodal changes pivoting between quiet and active phases. The rapid flux changes, the dips, and the power-law spectrum point toward the interpretation that this is a low-mass X-ray binary. Some temporal characteristics are similar to those in the Rapid Burster and GRO J1744-28, making XSS J12270-4859 a very rare object. \\ ( http://arxiv.org/abs/0904.4427 , 929kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4428 Date: Tue, 28 Apr 2009 15:31:32 GMT (269kb) Title: partly obscured accretion disk model to explain Shifted broad Balmer emission lines of Active Galactic Nuclei Authors: Xue-GUang Zhang, Deborah Dultzin, Ting-Gui Wang, Guinevere Kaufmann Categories: astro-ph.CO Comments: 15 pages, 7 figures, 2 tables, accepted by MNRAS \\ We present a new model to explain the appearance of red/blue-shifted broad low-ionization emission lines, especially emission lines in optical band, which is commonly considered as an indicator of radial motion of the line emitting gas in broad emission line regions (BLRs) of Active Galactic Nuclei (AGN). We show that partly obscured disk-like BLRs of dbp emitters (AGN with double-peak broad low-ionization emission lines) can also successfully produce shifted standard Gaussian broad balmer emission lines. Then we calculate two kinds of BH masses for AGN with shifted broad balmer emission lines selected from SDSS. We find that the BH masses calculated from M-sigma relation are systematically larger than virial BH masses for the selected objects, even after the correction of internal reddening effects in BLRs. The smaller virial BH masses than BH masses from M-sigma relation for objects with shifted broad emission lines are coincident with what we expect from the partly obscured accretion disk model. Thus, we provide an optional better model to explain the appearance of shifted broad emission lines, especially for those objects with underestimated virial BH masses. \\ ( http://arxiv.org/abs/0904.4428 , 269kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4433 Date: Tue, 28 Apr 2009 15:54:33 GMT (2944kb) Title: Structures of Local Galaxies Compared to High Redshift Star-forming Galaxies Authors: Sara M. Petty, Duilia F. de Mello, John S. Gallagher III, Jonathan P. Gardner, Jennifer M. Lotz, C. Matt Mountain, Linda J. Smith Categories: astro-ph.CO astro-ph.GA Comments: Submitted to the Astronomical Journal after responding to referee comments \\ The rest-frame far-ultraviolet (FUV) morphologies of 8 nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 8, NGC 520, NGC 1068, NGC 3079, NGC 3310, NGC 7673) are compared with 54 galaxies at z ~ 1.5 and 46 galaxies at z ~ 4 observed in the GOODS-ACS field. The nearby sample is artificially redshifted to z ~ 1.5 and 4. We compare the simulated galaxy morphologies to real z ~ 1.5 and 4 UV-bright galaxy morphologies. We calculate the Gini coefficient (G), the second-order moment of the brightest 20% of the galaxy's flux (M_20), and the Sersic index (n). We explore the use of nonparametric methods with 2D profile fitting and find the combination of M_20 with n an efficient method to classify galaxies as having merger, exponential disk, or bulge-like morphologies. When classified according to G and M_20, 20/30% of real/simulated galaxies at z ~ 1.5 and 37/12% at z ~ 4 have bulge-like morphologies. The rest have merger-like or intermediate distributions. Alternatively, when classified according to the Sersic index, 70% of the z ~ 1.5 and z ~ 4 real galaxies are exponential disks or bulge-like with n > 0.8, and ~30% of the real galaxies are classified as mergers. The artificially redshifted galaxies have n values with ~35% bulge or exponential at z ~ 1.5 and 4. Therefore, ~20-30% of Lyman-break galaxies (LBGs) have structures similar to local starburst mergers, and may be driven by similar processes. We assume merger-like or clumpy star-forming galaxies in the GOODS field have morphological structure with values n < 0.8 and M_20 > -1.7. We conclude that Mrk 8, NGC 3079, and NGC 7673 have structures similar to those of merger-like and clumpy star-forming galaxies observed at z ~ 1.5 and 4. \\ ( http://arxiv.org/abs/0904.4433 , 2944kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4445 Date: Tue, 28 Apr 2009 16:55:59 GMT (64kb) Title: On the correlation between metallicity and the presence of giant planets Authors: M. Haywood Categories: astro-ph.GA Comments: Accepted in ApJL \\ The correlation between stellar metallicity and the presence of giant planets is well established. It has been tentatively explained by the possible increase of planet formation probability in stellar disks with enhanced amount of metals. However, there are two caveats to this explanation. First, giant stars with planets do not show a metallicity distribution skewed towards metal-rich objects, as found for dwarfs. Second, the correlation with metallicity is not valid at intermediate metallicities, for which it can be shown that giant planets are preferentially found orbiting thick disk stars. None of these two peculiarities is explained by the proposed scenarios of giant planet formation. We contend that they are galactic in nature, and probably not linked to the formation process of giant planets. It is suggested that the same dynamical effect, namely the migration of stars in the galactic disk, is at the origin of both features, with the important consequence that most metal-rich stars hosting giant planets originate from the inner disk, a property that has been largely neglected until now. We illustrate that a planet-metallicity correlation similar to the observed one is easily obtained if stars from the inner disk have a higher percentage of giant planets than stars born at the solar radius, with no specific dependence on metallicity. We propose that the density of molecular hydrogen in the inner galactic disk (the molecular ring) could play a role in setting the high percentage of giant planets that originate from this region. \\ ( http://arxiv.org/abs/0904.4445 , 64kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4455 Date: Tue, 28 Apr 2009 18:07:43 GMT (3646kb) Title: The Young Stellar Population of IC1613. I. A New Catalogue of OB Associations Authors: M. Garcia (1), A. Herrero (1,2), B. Vicente (1,3), N. Castro (1,2), L. J. Corral (4), A. Rosenberg (1) and M. Monelli (1). ((1) IAC, (2) ULL, (3) IAA, (4) UDG) Categories: astro-ph.SR Comments: Accepted for publication in Astronomy and Astrophysics. 16 pages + appendix (14 pages); 20 figures \\ Context: Determining the parameters of massive stars is crucial to understand many processes in galaxies and the Universe, since these objects are important sources of ionization, chemical enrichment and momentum. 10m class telescopes enable us to perform detailed quantitative spectroscopic analyses of massive stars in other galaxies, sampling areas of different metallicity. Relating the stars to their environment is crucial to understand the physical processes ruling their formation and evolution. Aims: In preparation for the GTC, our goal is to build a catalogue of massive star candidates in the metal-poor irregular galaxy IC1613 with high astrometric accuracy, apt for the current generation of multi-object spectrographs. A census of OB associations in this galaxy is also needed, to provide important additional information about age and environment of the candidate OB stars. Methods: From INT-WFC observations, we have built an astrometric and photometric catalogue of stars in IC1613. Candidate blue massive stars are preselected from their colors. A friends-of-friends algorithm is developed to find their clustering in the galaxy. While a common physical origin for all the members of the associations cannot be ensured, this is a necessary first step to place candidate OB stars in a population context. Results: We have produced a deep catalogue of targets in IC1613 that covers a large field of view. To achieve high astrometric accuracy a new astrometric procedure is developed for the INT-WFC data. We have also built a catalogue of OB associations in IC1613. We have found that they concentrate in the central regions, specially in the HII bubbles. The study of extinction confirms that it is patchy, with local values of color-excess above the foreground value. \\ ( http://arxiv.org/abs/0904.4455 , 3646kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4463 Date: Tue, 28 Apr 2009 19:24:39 GMT (648kb) Title: The ACS LCID Project. I. Short-Period Variables in the Isolated Dwarf Spheroidal Galaxies Cetus & Tucana Authors: Edouard J. Bernard, Matteo Monelli, Carme Gallart, Igor Drozdovsky, Peter B. Stetson, Antonio Aparicio, Santi Cassisi, Lucio Mayer, Andrew A. Cole, Sebastian L. Hidalgo, Evan D. Skillman, Eline Tolstoy Categories: astro-ph.SR astro-ph.CO Comments: 26 pages, 24 figures, in emulateapj format. To be published in ApJ. Some figures heavily degraded; See http://www.iac.es/project/LCID/?p=publications for a version with full resolution figures \\ (abridged) We present the first study of the variable star populations in the isolated dwarf spheroidal galaxies (dSph) Cetus and Tucana. Based on Hubble Space Telescope images obtained with the Advanced Camera for Surveys in the F475W and F814W bands, we identified 180 and 371 variables in Cetus and Tucana, respectively. The vast majority are RR Lyrae stars. In Cetus we also found three anomalous Cepheids, four candidate binaries and one candidate long-period variable (LPV), while six anomalous Cepheids and seven LPV candidates were found in Tucana. Of the RR Lyrae stars, 147 were identified as fundamental mode (RRab) and only eight as first-overtone mode (RRc) in Cetus, with mean periods of 0.614 and 0.363 day, respectively. In Tucana we found 216 RRab and 82 RRc giving mean periods of 0.604 and 0.353 day. These values place both galaxies in the so-called Oosterhoff Gap, as is generally the case for dSph. We calculated the distance modulus to both galaxies using different approaches based on the properties of RRab and RRc, namely the luminosity-metallicity and period-luminosity-metallicity relations, and found values in excellent agreement with previous estimates using independent methods: (m-M)_{0,Cet}=24.46+-0.12 and (m-M)_{0,Tuc}=24.74+-0.12, corresponding to 780+-40 kpc and 890+-50 kpc. We also found numerous RR Lyrae variables pulsating in both modes simultaneously (RRd): 17 in Cetus and 60 in Tucana. Tucana is, after Fornax, the second dSph in which such a large fraction of RRd (~17%) has been observed. We provide the photometry and pulsation parameters for all the variables, and compare the latter with values from the literature for well-studied dSph of the Local Group and Galactic globular clusters. \\ ( http://arxiv.org/abs/0904.4463 , 648kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- ------------------------------------------------------------------------------ \\ arXiv:0904.3276 (*cross-listing*) Date: Tue, 21 Apr 2009 19:05:10 GMT (102kb) Date (revised v2): Mon, 27 Apr 2009 09:33:44 GMT (103kb) Title: Gluon condensate, modified gravity, and the accelerating Universe Authors: F.R. Klinkhamer Categories: gr-qc astro-ph.CO Comments: 20 pages Report-no: KA-TP-02-2009 \\ The dynamics of a gravitating gluon condensate q is studied in the context of a spatially flat Friedmann-Robertson-Walker universe. With a quadratic approximation of the gravitating gluon-condensate vacuum energy density \rho_{V}(q) near the equilibrium value q_{0} and a small modified-gravity coupling constant \eta of a nonanalytic \tilde{f}(R,q) term in the action, an "accelerating universe" is obtained which more or less resembles the present Universe. The unknown component 'X' of this model universe (here, due to the combined effects of vacuum energy density and modified gravity) has an effective equation-of-state parameter \bar{w}_{X} which is found to evolve towards the value -1 from above. \\ ( http://arxiv.org/abs/0904.3276 , 103kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4187 (*cross-listing*) Date: Mon, 27 Apr 2009 15:34:24 GMT (14kb) Date (revised v2): Mon, 27 Apr 2009 20:05:28 GMT (15kb) Title: Cosmological Perturbations and Non-Gaussianities in Ho\v{r}ava-Lifshitz Gravity Authors: Xian Gao Categories: hep-th astro-ph.CO gr-qc Comments: 11 pages, no figure Report-no: CAS-KITPC/ITP-110 \\ We investigate cosmological perturbations and non-gaussianities in Ho\v{r}ava-Lifshitz theory of gravitation, including metric perturbations. In the UV limit, the scalar perturbation in Ho\v{r}ava theory is naturally scale-invariant, ignoring the details of the expansion of the universe. Thus one may relax the exponential inflation and the slow-roll conditions for the inflaton field. Moreover, in the absence of slow-roll conditions, it is possible that the "slow-roll suppressed" non-gaussianities resume to become large. We calculate the non-gaussianities from the bispectrum of the perturbation and find that, the equilateral-type non-gaussianity is of order unity, while the local-type non-gaussianity remains small as in usual single-field slow-roll inflation model in general relativity. \\ ( http://arxiv.org/abs/0904.4187 , 15kb) %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% ------------------------------------------------------------------------------ \\ arXiv:0709.2130 (*cross-listing*) replaced with revised version Mon, 27 Apr 2009 21:06:02 GMT (824kb) Title: Effective growth of matter density fluctuations in the running LCDM and LXCDM models Authors: Javier Grande, Reuven Opher, Ana Pelinson, Joan Sola Categories: gr-qc astro-ph hep-ph hep-th Comments: LaTeX, 38 pages, 8 figures. Version accepted in JCAP Report-no: UB-ECM-PF 07/26 Journal-ref: JCAP 0712:007,2007 DOI: 10.1088/1475-7516/2007/12/007 \\ ( http://arxiv.org/abs/0709.2130 , 824kb) ------------------------------------------------------------------------------ \\ arXiv:0803.4507 replaced with revised version Tue, 28 Apr 2009 15:05:31 GMT (90kb) Title: Recombination Lines and Free-Free Continua formed in Asymptotic Ionized Winds: Analytic solution for the radiative transfer Authors: Richard Ignace Categories: astro-ph Comments: to appear in Astronomische Nachrichten (astroph submission is a preprint version) \\ ( http://arxiv.org/abs/0803.4507 , 90kb) ------------------------------------------------------------------------------ \\ arXiv:0807.4702 replaced with revised version Tue, 28 Apr 2009 12:06:05 GMT (157kb) Title: The Assembly of Supermassive Black Holes at High Redshifts Authors: Takamitsu Tanaka and Zolt\'an Haiman (Columbia University) Categories: astro-ph Comments: 60 preprint pages with 15 figures, ApJ accepted version Journal-ref: Astrophysical Journal 696 (2009) 1798-1822 \\ ( http://arxiv.org/abs/0807.4702 , 157kb) ------------------------------------------------------------------------------ \\ arXiv:0808.4099 replaced with revised version Mon, 27 Apr 2009 20:43:22 GMT (251kb) Title: The Influence of Concentration and Dynamical State on Scatter in the Galaxy Cluster Mass-Temperature Relation Authors: H.-Y. Yang (1), P. M. Ricker (1,2), P. M. Sutter (1) ((1) University of Illinois, (2) NCSA) Categories: astro-ph Comments: Accepted for publication in ApJ (17 pages, 13 figures, double column), updated to match version to appear in ApJ \\ ( http://arxiv.org/abs/0808.4099 , 251kb) ------------------------------------------------------------------------------ \\ arXiv:0809.1397 replaced with revised version Tue, 28 Apr 2009 18:18:02 GMT (84kb) Title: Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds Authors: Mark Heyer, Coleman Krawczyk, Julia Duval, James M. Jackson Categories: astro-ph Comments: Accepted by ApJ. Newest version includes modifications from the referee \\ ( http://arxiv.org/abs/0809.1397 , 84kb) ------------------------------------------------------------------------------ \\ arXiv:0809.2095 replaced with revised version Tue, 28 Apr 2009 05:53:11 GMT (109kb) Title: Kozai cycles, tidal friction and the dynamical evolution of binary minor planets Authors: Hagai B. Perets, Smadar Naoz Categories: astro-ph Comments: 5 pages, 2 figures. Appendix removed (to appear in another paper), added and corrected observational data. Results strengthened. Submitted to ApJL \\ ( http://arxiv.org/abs/0809.2095 , 109kb) ------------------------------------------------------------------------------ \\ arXiv:0811.0718 replaced with revised version Tue, 28 Apr 2009 08:59:12 GMT (683kb) Title: The first two transient supersoft X-ray sources in M 31 globular clusters and the connection to classical novae Authors: M. Henze, W. Pietsch, F. Haberl, G. Sala, R. Quimby, M. Hernanz, M. Della Valle, P. Milne, G.G. Williams, V. Burwitz, J. Greiner, H. Stiele, D.H. Hartmann, A.K.H. Kong, and K. Hornoch Categories: astro-ph Comments: 11 pages, 9 figures, 4 tables, submitted to A&A; v2: accepted version \\ ( http://arxiv.org/abs/0811.0718 , 683kb) ------------------------------------------------------------------------------ \\ arXiv:0811.1333 (*cross-listing*) replaced with revised version Tue, 28 Apr 2009 10:32:28 GMT (187kb) Title: Theoretical Limits on the Equation-of-State Parameter of Phantom Cosmology Authors: Emmanuel N. Saridakis Categories: hep-th astro-ph gr-qc Comments: 7 pages, 7 figures \\ ( http://arxiv.org/abs/0811.1333 , 187kb) ------------------------------------------------------------------------------ \\ arXiv:0812.3031 (*cross-listing*) replaced with revised version Tue, 28 Apr 2009 13:34:21 GMT (68kb) Title: Supernova neutrino three-flavor evolution with dominant collective effects Authors: Gianluigi Fogli, Eligio Lisi, Antonio Marrone, Irene Tamborra (U. of Bari & INFN, Bari) Categories: hep-ph astro-ph hep-ex Comments: 22 pages, including 9 figures (1 section with 3 figures added). Accepted for publication in JCAP Journal-ref: JCAP04(2009)030 \\ ( http://arxiv.org/abs/0812.3031 , 68kb) ------------------------------------------------------------------------------ \\ arXiv:0812.3234 (*cross-listing*) replaced with revised version Tue, 28 Apr 2009 13:42:47 GMT (703kb,D) Title: Bifurcation and pattern changing with two real scalar fields Authors: P.P. Avelino, D. Bazeia, R. Menezes, J. Oliveira Categories: hep-th astro-ph hep-ph nlin.PS Comments: 10 pages, 32 figures, published version Journal-ref: Phys. Rev. D 79, 085007 (2009) \\ ( http://arxiv.org/abs/0812.3234 , 703kb) ------------------------------------------------------------------------------ \\ arXiv:0812.4420 replaced with revised version Tue, 28 Apr 2009 09:13:42 GMT (35kb) Title: The very short supersoft X-ray state of the classical nova M31N 2007-11a Authors: M. Henze, W. Pietsch, G. Sala, M. Della Valle, M. Hernanz, J. Greiner, V. Burwitz, M. J. Freyberg, F. Haberl, D. H. Hartmann, P. Milne, G. G. Williams Categories: astro-ph Comments: 4 pages, 2 figures, 2 tables, submitted to A&A Letters; v2: accepted version \\ ( http://arxiv.org/abs/0812.4420 , 35kb) ------------------------------------------------------------------------------ \\ arXiv:0812.5083 replaced with revised version Tue, 28 Apr 2009 10:30:18 GMT (222kb) Title: Catastrophic Photo-z Errors and the Dark Energy Parameter Estimates with Cosmic Shear Authors: L. Sun, Z.-H. Fan, C. Tao, J.-P. Kneib, S. Jouvel, A. Tilquin Categories: astro-ph Comments: 25 pages, 9 figures. Revised version, as accepted for publication in ApJ \\ ( http://arxiv.org/abs/0812.5083 , 222kb) ------------------------------------------------------------------------------ \\ arXiv:0901.2262 replaced with revised version Tue, 28 Apr 2009 03:05:38 GMT (402kb) Title: Holographic Ricci dark energy: Current observational constraints, quintom feature, and the reconstruction of scalar-field dark energy Authors: Xin Zhang Categories: astro-ph.CO gr-qc hep-ph hep-th Comments: 26 pages, 10 figures; fig.8 revised; accepted for publication in Phys.Rev.D \\ ( http://arxiv.org/abs/0901.2262 , 402kb) ------------------------------------------------------------------------------ \\ arXiv:0901.4861 replaced with revised version Tue, 28 Apr 2009 18:22:49 GMT (340kb) Title: The test for suppressed dynamical friction in a constant density core of dwarf galaxies Authors: Shigeki M. Inoue Categories: astro-ph.CO astro-ph.GA Comments: 8pages,9figures, submitted to MNRAS \\ ( http://arxiv.org/abs/0901.4861 , 340kb) ------------------------------------------------------------------------------ \\ arXiv:0903.2390 replaced with revised version Tue, 28 Apr 2009 09:57:04 GMT (377kb) Title: Two-Phase Galaxy Formation Authors: M. Cook, A. Lapi, G.L. Granato Categories: astro-ph.GA astro-ph.CO Comments: 16 pages, 21 figures, MNRAS Accepted 23/04/2009 \\ ( http://arxiv.org/abs/0903.2390 , 377kb) ------------------------------------------------------------------------------ \\ arXiv:0903.2517 replaced with revised version Tue, 28 Apr 2009 00:35:08 GMT (1171kb,D) Title: Interferometric science results on young stellar objects Authors: Fabien Malbet Categories: astro-ph.SR astro-ph.IM Comments: 18 pages, 6 figures, invited lecture at the VLTI school on "Astrometry and Imaging with the Very Large Telescope Interferometer", 2-13 June 2008, Keszthely, Hungary. v2: typos corrected; v3: reference added \\ ( http://arxiv.org/abs/0903.2517 , 1171kb) ------------------------------------------------------------------------------ \\ arXiv:0903.5428 replaced with revised version Tue, 28 Apr 2009 11:21:19 GMT (95kb) Title: The moduli problem at the perturbative level Authors: Martin Lemoine (IAP), Jerome Martin (IAP) and Jun'ichi Yokoyama (RESCEU) Categories: astro-ph.CO gr-qc hep-ph hep-th Comments: 4 pages, 3 figures (revtex) -- v2: an important correction on the amplitude/transfer of isocurvature modes at the end of inflation, typos corrected, references added, basic result unchanged Report-no: RESCEU-10/09 \\ ( http://arxiv.org/abs/0903.5428 , 95kb) ------------------------------------------------------------------------------ \\ arXiv:0904.0126 replaced with revised version Tue, 28 Apr 2009 11:30:30 GMT (382kb) Title: Constraints on moduli cosmology from the production of dark matter and baryon isocurvature fluctuations Authors: Martin Lemoine (IAP), Jerome Martin (IAP) and Jun'ichi Yokoyama (RESCEU) Categories: astro-ph.CO gr-qc hep-ph hep-th Comments: 46 pages, 8 figures (revtex) -- v2: an important correction on the amplitude/transfer of isocurvature modes at the end of inflation, typos corrected, references and discussion added, basic result unchanged Report-no: RESCEU-11/09 \\ ( http://arxiv.org/abs/0904.0126 , 382kb) ------------------------------------------------------------------------------ \\ arXiv:0904.0681 replaced with revised version Tue, 28 Apr 2009 07:25:15 GMT (313kb) Title: Interpreting a Dwarf Nova Eruption as Magnetic Flare Activity Authors: Noam Soker (Technion), Saeqa Dil Vrtilek (CfA) Categories: astro-ph.HE astro-ph.SR Comments: astro-ph paper only \\ ( http://arxiv.org/abs/0904.0681 , 313kb) ------------------------------------------------------------------------------ \\ arXiv:0904.0877 replaced with revised version Tue, 28 Apr 2009 10:49:57 GMT (19kb) Title: Dynamics of a scalar field in Robertson-Walker spacetimes Authors: Edmund J. Copeland, Shuntaro Mizuno, and Maryam Shaeri Categories: astro-ph.CO gr-qc hep-th Comments: 10 pages, v2:references added. Accepted for publication in PRD \\ ( http://arxiv.org/abs/0904.0877 , 19kb) ------------------------------------------------------------------------------ \\ arXiv:0904.1583 replaced with revised version Tue, 28 Apr 2009 14:26:29 GMT (332kb) Title: Perturbed dark energy: classical scalar field versus tachyon Authors: Olga Sergijenko, Bohdan Novosyadlyj Categories: astro-ph.CO Comments: 13 pages, 7 figures, minor corrections, references added \\ ( http://arxiv.org/abs/0904.1583 , 332kb) ------------------------------------------------------------------------------ \\ arXiv:0904.2218 replaced with revised version Tue, 28 Apr 2009 19:36:44 GMT (156kb) Title: Clarifying Forecasts of Dark Energy Constraints from Baryon Acoustic Oscillations Authors: Yun Wang Categories: astro-ph.CO Comments: 10 pages, 10 color figures. Text revised. Some typos corrected. Results unchanged \\ ( http://arxiv.org/abs/0904.2218 , 156kb) ------------------------------------------------------------------------------ \\ arXiv:0904.3146 replaced with revised version Tue, 28 Apr 2009 02:23:05 GMT (354kb) Title: A Quasi-Stationary Solution to Gliese 436b's Eccentricity Authors: Konstantin Batygin, Gregory Laughlin, Stefano Meschiari, Eugenio Rivera, Steve Vogt, Paul Butler Categories: astro-ph.EP Comments: 25 pages, 7 figures. Accepted for publication in the Astrophysical Journal \\ ( http://arxiv.org/abs/0904.3146 , 354kb) ------------------------------------------------------------------------------ \\ arXiv:0904.4031 replaced with revised version Tue, 28 Apr 2009 08:19:08 GMT (34kb) Title: Extending the Eigenvector 1 Space to the Optical Variability of Quasars Authors: Yufeng Mao, Jing Wang, Jianyan Wei Categories: astro-ph.CO Comments: 16 pages, 4 figures \\ ( http://arxiv.org/abs/0904.4031 , 34kb) %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- For subscribe options to combined physics archives, e-mail To: physics@arXiv.org, Subject: subscribe ----------------------------------------------------------------------------- For help on viewing and making submissions, see http://arXiv.org/help/ For a list of archive mirror sites, see http://arXiv.org/servers.html ----------------------------------------------------------------------------- Third-party submissions cause excessive problems. 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