Daddi paper paper from English about emission line search arXiv:0911.3151 [ps, pdf, other] Title: The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation Authors: Charlie Conroy, James E. Gunn Comments: 26 pages, 16 figures, submitted to ApJ. The FSPS code can be downloaded at this http URL Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) Stellar population synthesis (SPS) provides the link between the stellar and dust content of galaxies and their observed spectral energy distributions. In the present work we perform a comprehensive calibration of our own flexible SPS (FSPS) model against a suite of data. Several public SPS models are intercompared, including the models of Bruzual & Charlot (BC03), Maraston (M05) and FSPS. The relative strengths and weaknesses of these models are evaluated, with the following conclusions: 1) The FSPS and BC03 models compare favorably with MC data at all ages, whereas M05 colors are too red and the age-dependence is incorrect; 2) All models yield similar optical and near-IR colors for old metal-poor systems, and yet they all provide poor fits to the integrated J-K and V-K colors of both MW and M31 star clusters; 4) All models predict ugr colors too red, D4000 strengths too strong and Hdelta strengths too weak compared to massive red sequence galaxies, under the assumption that such galaxies are composed solely of old metal-rich stars; 5) FSPS and, to a lesser extent, BC03 can reproduce the optical and near-IR colors of post-starburst galaxies, while M05 cannot. Reasons for these discrepancies are explored. The failure at predicting the ugr colors, D4000, and Hdelta strengths can be explained by some combination of a minority population of metal-poor stars, young stars, blue straggler and/or blue horizontal branch stars, but not by appealing to inadequacies in either theoretical stellar atmospheres or canonical evolutionary phases (e.g., the main sequence turn-off). We emphasize that due to a lack of calibrating star cluster data in regions of the metallicity-age plane relevant for galaxies, all of these models continue to suffer from serious uncertainties that are difficult to quantify. (ABRIDGED) arXiv:0911.3156 [ps, pdf, other] Title: Fake star formation bursts: blue horizontal branch stars masquerade as young stars in optical integrated light spectroscopy Authors: P. Ocvirk Comments: 14 pages, 6 figures, accepted for publication in ApJ Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) Model color magnitude diagrams of low-metallicity globular clusters usually show a deficit of hot evolved stars with respect to observations. We investigate quantitatively the impact of such modelling inaccuracies on the significance of star formation history reconstructions obtained from optical integrated spectra. To do so, we analyse the sample of spectra of galactic globular clusters of Schiavon et al. with STECKMAP (Ocvirk et al.) and the stellar population models Vazdekis et al. and Bruzual & Charlot, and focus on the reconstructed stellar age distributions. Firstly, we show that background/foreground contamination correlates with E(B-V), which allows us to define a clean subsample of uncontaminated GCs, on the basis of a E(B-V) filtering. We then identify a "confusion zone" where fake young bursts of star formation pop up in the star formation history although the observed population is genuinely old. These artifacts appear for 70-100% of cases depending on the population model used, and contribute up to 12% of the light in the optical. Their correlation with the horizontal branch ratio indicates that the confusion is driven by HB morphology: red horizontal branch clusters are well fitted by old stellar population models while those with a blue HB require an additional hot component. The confusion zone extends over [Fe/H]=[-2,-1.2], although we lack the data to probe extreme high and low metallicity regimes. As a consequence, any young starburst superimposed on an old stellar population in this metallicity range could be regarded as a modeling artifact, if it weighs less than 12% of the optical light, and if no emission lines typical of an HII region are present. arXiv:0911.3156 [ps, pdf, other] Title: Fake star formation bursts: blue horizontal branch stars masquerade as young stars in optical integrated light spectroscopy Authors: P. Ocvirk Comments: 14 pages, 6 figures, accepted for publication in ApJ Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) Model color magnitude diagrams of low-metallicity globular clusters usually show a deficit of hot evolved stars with respect to observations. We investigate quantitatively the impact of such modelling inaccuracies on the significance of star formation history reconstructions obtained from optical integrated spectra. To do so, we analyse the sample of spectra of galactic globular clusters of Schiavon et al. with STECKMAP (Ocvirk et al.) and the stellar population models Vazdekis et al. and Bruzual & Charlot, and focus on the reconstructed stellar age distributions. Firstly, we show that background/foreground contamination correlates with E(B-V), which allows us to define a clean subsample of uncontaminated GCs, on the basis of a E(B-V) filtering. We then identify a "confusion zone" where fake young bursts of star formation pop up in the star formation history although the observed population is genuinely old. These artifacts appear for 70-100% of cases depending on the population model used, and contribute up to 12% of the light in the optical. Their correlation with the horizontal branch ratio indicates that the confusion is driven by HB morphology: red horizontal branch clusters are well fitted by old stellar population models while those with a blue HB require an additional hot component. The confusion zone extends over [Fe/H]=[-2,-1.2], although we lack the data to probe extreme high and low metallicity regimes. As a consequence, any young starburst superimposed on an old stellar population in this metallicity range could be regarded as a modeling artifact, if it weighs less than 12% of the optical light, and if no emission lines typical of an HII region are present. arXiv:0911.3302 [ps, pdf, other] Title: LoCuSS: First Results from Strong-lensing Analysis of 20 Massive Galaxy Clusters at z~0.2 Authors: Johan Richard (Durham), Graham Smith (Birmingham), Jean-Paul Kneib (Marseille), Richard Ellis (Caltech), Alastair Sanderson (Birmingham), Liuyi Pei (Caltech), Thomas Targett (UBC), David Sand (Harvard), Mark Swinbank (Durham), Helmut Dannerbauer (Heidelberg), Pascuale Mazzotta (Roma), Marceau Limousin (Marseille), Eiichi Egami (Tucson), Eric Jullo (JPL), Victoria Hamilton-Morris (Birmingham), Sean Moran (Johan Hopkins) Comments: 26 pages, 14 figures, resubmitted to MNRAS, including response to the referee Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) We present a statistical analysis of a sample of 20 strong lensing clusters drawn from the Local Cluster Substructure Survey (LoCuSS), based on high resolution Hubble Space Telescope imaging of the cluster cores and follow-up spectroscopic observations using the Keck-I telescope. We use detailed parameterized models of the mass distribution in the cluster cores, to measure the total cluster mass and fraction of that mass associated with substructures within R<250kpc.These measurements are compared with the distribution of baryons in the cores, as traced by the old stellar populations and the X-ray emitting intracluster medium. Our main results include: (i) the distribution of Einstein radii is log-normal, with a peak and 1sigma width of =1.16+/-0.28; (ii) we detect an X-ray/lensing mass discrepancy of =1.3 at 3 sigma significance -- clusters with larger substructure fractions displaying greater mass discrepancies, and thus greater departures from hydrostatic equilibrium; (iii) cluster substructure fraction is also correlated with the slope of the gas density profile on small scales, implying a connection between cluster-cluster mergers and gas cooling. Overall our results are consistent with the view that cluster-cluster mergers play a prominent role in shaping the properties of cluster cores, in particular causing departures from hydrostatic equilibrium, and possibly disturbing cool cores. Our results do not support recent claims that large Einstein radius clusters present a challenge to the CDM paradigm. arXiv:0911.3368 [ps, pdf, other] Title: The clustering properties of the first galaxies Authors: M. Stiavelli (STScI), M. Trenti (U. Colorado) Comments: 11 pages including 4 figures. Originally submitted to ApJL on Sept. 11, 2009. Resubmittted on Nov.17, 2009 Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) We consider the clustering properties of the first galaxies formed in the Universe. Due to the chemical enrichment of the inter-stellar medium by isolated Population III stars formed in minihalos at redshift z >~ 30, the chronologically first galaxies are composed of metal-poor Population II stars and are highly clustered. Chemically pristine galaxies in halos with mass M ~ 10^8 M_sun may form instead at z<20 in relatively underdense regions of the Universe once self-enrichment by Population III in minihalos is quenched by the build-up of an H_2 photo-dissociating radiative background in the Lyman-Werner bands. We find that these chemically pristine galaxies are essentially uncorrelated so we expect that deep fields with the James Webb Space Telescope will not be seriously affected by cosmic variance for these objects. We predict that 10 <~ z <~ 15 metal-free galaxies have area densities of about 80 per arcmin square and per unit redshift but most of them will be too faint even for JWST. However, the predicted density makes these objects interesting targets for searches behind lensing clusters. [2] arXiv:0911.3392 [ps, pdf, other] Title: The initial mass function of early-type galaxies Authors: T.Treu (1), M.W.Auger (1), L.V.E.Koopmans (2), R.Gavazzi (3), P.J.Marshall (1), A.S.Bolton (4) ((1) UCSB; (2) Kapteyn; (3) IAP; (4) Utah) Comments: 10 pages 4 figures. Resubmitted to ApJ taking into account referee's comments Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) We determine an absolute calibration of the initial mass function (IMF) of early-type galaxies, by studying a sample of 56 gravitational lenses identified by the SLACS Survey. Under the assumption of standard Navarro, Frenk & White dark matter halos, a combination of lensing, dynamical, and stellar population synthesis models is used to disentangle the stellar and dark matter contribution for each lens. We define an "IMF mismatch" parameter \alpha=M*(L+D)/M*(SPS) as the ratio of stellar mass inferred by a joint lensing and dynamical models (M*(L+D)) to the current stellar mass inferred from stellar populations synthesis models (M*(SPS)). We find that a Salpeter IMF provides stellar masses in agreement with those inferred by lensing and dynamical models (<\log \alpha>=0.00+-0.03+-0.02), while a Chabrier IMF underestimates them (<\log \alpha>=0.25+-0.03+-0.02). A tentative trend is found, in the sense that \alpha appears to increase with galaxy velocity dispersion. Taken at face value, this result would imply a non universal IMF, perhaps dependent on metallicity, age, or abundance ratios of the stellar populations. Alternatively, the observed trend may imply non-universal dark matter halos with inner density slope increasing with velocity dispersion. While the degeneracy between the two interpretations cannot be broken without additional information, the data imply that massive early-type galaxies cannot have both a universal IMF and universal dark matter halos. arXiv:0911.3593 [ps, pdf, other] Title: The Submillimetre Properties of Ultraluminous Infrared Galaxies Authors: D.L. Clements, L. Dunne, S.A. Eales Comments: Accepted for publication in MNRAS Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) We present the results of SCUBA observations of a complete sample of local ULIRGs. Twenty of the initial sample of 23 sources are detected at 850 um and nearly half of the objects are also detected at 450 um. This data is combined with existing observations of a further seven ULIRGs to produce the largest sample of submm observations of ULIRGs currently available. We use similar techniques to the SLUGS survey to fit dust spectral energy distributions (SEDs) to their far-IR emission. We find that ULIRGs have a higher dust temperature than lower luminosity objects (42K compared to 35K) and a steeper emissivity index. For those objects where 450 um fluxes are available we also attempt a two component dust SED fit, with warm and cool dust and a dust emissivity index of beta=2. Such a model has been found to be a good fit to lower luminosity systems. We find that it also works well for ULIRGs, but that ULIRGs have a smaller cold dust component. Comparison of the dust mass derived for ULIRGs and more normal spiral galaxies suggests that the dust content of a ULIRG is simply the combined dust content of the two galaxies whose merger has triggered the ULIRG activity. We examine the high end of the 850 um luminosity function and find results consistent with those of the earlier SLUGS survey. We also find that ULIRGs make up only about 50% of the high end of the 850 um luminosity function, with LIRGs containing a large mass of cool dust likely to be responsible for the rest arXiv:0911.3654 [ps, pdf, other] Title: Local Group Dwarf Elliptical Galaxies: II. Stellar Kinematics to Large Radii in NGC 147 and NGC 185 Authors: M. Geha, R. P. van der Marel, P. Guhathakurta, K. M. Gilbert, J. Kalirai, E. N. Kirby Comments: 16 pages, 7 figures. submitted to AJ, minor revisions made in response to referee Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) We present kinematic and metallicity profiles for the M31 dwarf elliptical (dE) satellite galaxies NGC 147 and NGC 185. The profiles represent the most extensive spectroscopic radial coverage for any dE galaxy, extending to a projected distance of eight half-light radii (8 r_eff = 14'). We achieve this coverage via Keck/DEIMOS multislit spectroscopic observations of 520 and 442 member red giant branch stars in NGC 147 and NGC 185, respectively. Contrary to previous studies, we find that both dEs have significant internal rotation. We measure a maximum rotational velocity of 17+/-2 km/s for NGC 147 and 15+/-5 km/s for NGC 185. The velocity dispersions decrease gently with radius with an average dispersion of 16+/-1 km/s for NGC 147 and 24+/-1 km/s for NGC 185. Both dEs have internal metallicity dispersions of 0.5 dex, but show no evidence for a radial metallicity gradient. We construct two-integral axisymmetric dynamical models and find that the observed kinematical profiles cannot be explained without modest amounts of non-baryonic dark matter. We measure central mass-to-light ratios of ML_V = 4.2+/-0.6 and ML_V = 4.6+/-0.6 for NGC 147 and NGC 185, respectively. Both dE galaxies are consistent with being primarily flattened by their rotational motions, although some anisotropic velocity dispersion is needed to fully explain their observed shapes. The velocity profiles of all three Local Group dEs (NGC 147, NGC 185 and NGC 205) suggest that rotation is more prevalent in the dE galaxy class than previously assumed, but is often manifest only at several times the effective radius. Since all dEs outside the Local Group have been probed to only inside the effective radius, this opens the door for formation mechanisms in which dEs are transformed or stripped versions of gas-rich rotating progenitor galaxies. arXiv:0911.3666 [ps, pdf, other] Title: Revealing an Energetic Galaxy-Wide Outflow in a z~2 Ultraluminous Infrared Galaxy Authors: D.M. Alexander (Durham), A.M. Swinbank, I. Smail, R. McDermid, N.P.H. Nesvadba Comments: 6 pages, 3 figures, to appear in Proceedings of "Accretion and Ejection in AGN: A Global View", Lake Como, Italy, June 22-26, 2009, ASP conference series. Based on arXiv:0911.0014 which is now MNRAS, in press Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) Leading models of galaxy formation require large-scale energetic outflows to regulate the growth of distant galaxies and their central black holes. However, current observational support for this hypothesis at high redshift is mostly limited to rare z>2 radio galaxies. Here we present Gemini-North NIFS Intregral Field Unit (IFU) observations of the [O III]5007 emission from a z~2 ultraluminous infrared galaxy (ULIRG; L_IR>10^12 L_sol) with an optically identified Active Galactic Nucleus (AGN). The spatial extent (~4-8 kpc) of the high velocity and broad [O III] emission are consistent with that found in z>2 radio galaxies, indicating the presence of a large-scale energetic outflow in a galaxy population potentially orders of magnitude more common than distant radio galaxies. The low radio luminosity of this system indicates that radio-bright jets are unlikely to be responsible for driving the outflow. However, the estimated energy input required to produce the large-scale outflow signatures (of order ~10^59 ergs over ~30 Myrs) could be delivered by a wind radiatively driven by the AGN and/or supernovae winds from intense star formation. The energy injection required to drive the outflow is comparable to the estimated binding energy of the galaxy spheroid, suggesting that it can have a significant impact on the evolution of the galaxy. We argue that the outflow observed in this system is likely to be comparatively typical of the high-redshift ULIRG population and discuss the implications of these observations for galaxy formation models. arXiv:0911.3740 [ps, pdf, other] Title: The VIMOS VLT Deep Survey: the group catalogue Authors: O. Cucciati, C. Marinoni, A. Iovino, S. Bardelli, C. Adami, A. Mazure, M. Scodeggio, D. Maccagni, S. Temporin, E. Zucca, G. De Lucia, J. Blaizot, B. Garilli, B. Meneux, G. Zamorani, O. Le Fèvre, A. Cappi, L. Guzzo, D. Bottini, V. Le Brun, L. Tresse, G. Vettolani, A. Zanichelli, S. Arnouts, M. Bolzonella, S. Charlot, P. Ciliegi, T. Contini, S. Foucaud, P. Franzetti, I. Gavignaud, O. Ilbert, F. Lamareille, H.J. McCracken, B. Marano, R. Merighi, S. Paltani, R. Pellò, A. Pollo, L. Pozzetti, D. Vergani, E. Pérez-Montero Comments: Submitted to A&A, revised version after referee comments Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO) [Abridged] We used the purely flux limited (17.5<=I<=24.0) VIMOS-VLT Deep Survey (VVDS) sample to produce a homogeneous and complete optically-selected group catalogue, with reliable group properties. Using mock catalogues extracted from the MILLENNIUM simulations, we first studied how many groups can potentially be found in a survey with the same sampling rate as the VVDS, and then we tested how well the virial line of sight velocity dispersion (s_los) of such groups can be measured using galaxy velocities. We verified that, given VVDS observational strategy, we are able to recover s_los when s_los >= 350 km/s. We then optimized our group-finding algorithm, based on the Voronoi-Delaunay method, training it on mocks mimicking all the VVDS survey strategies: we required the redshift and s_los distributions of the output groups (n(z) and n(s_los)) to be in agreement with those given by the group halos defined in the simulations. We also maximized the completeness (C) and purity (P) of the output group catalogue. We then applied the algorithm to VVDS real data. We obtained a catalogue of 318 groups of galaxies within 0.2 <= z <= 1.0, globally with C=60% and P=50% and with n(z) and n(s_los>= 350 km/s) in agreement with those present in the simulations. Finally, we studied the fraction f_b of blue galaxies (U-B <= 1), for a complete subsample of galaxies in the range 0.2 <= z <= 1, and we found that f_b in groups is always significantly lower than f_b when considering all galaxies irrespectively of their environment: both f_b increase significantly with redshift, with a possibly steeper increase for group galaxies. We also found a general trend for f_b decreasing for increasing group richness, at any redshift explored.