Topic
Star formation
About: Star formation is a research topic. Over the lifetime, 37405 publications have been published within this topic receiving 1808161 citations. The topic is also known as: astrogenesis.
Papers published on a yearly basis
Papers
More filters
••
University of California, Berkeley1, Lawrence Berkeley National Laboratory2, Institute for the Physics and Mathematics of the Universe3, New York University4, SLAC National Accelerator Laboratory5, California Institute of Technology6, Centre national de la recherche scientifique7, University of Zurich8, Space Telescope Science Institute9, ETH Zurich10, Institut d'Astrophysique de Paris11, University of Edinburgh12, Leiden University13, University of Waterloo14
TL;DR: In this paper, the authors performed a joint analysis of galaxy-galaxy weak lensing, galaxy spatial clustering, and galaxy number densities using a self-consistent theoretical framework.
Abstract: Using data from the COSMOS survey, we perform the first joint analysis of galaxy-galaxy weak lensing, galaxy spatial clustering, and galaxy number densities. Carefully accounting for sample variance and for scatter between stellar and halo mass, we model all three observables simultaneously using a novel and self-consistent theoretical framework. Our results provide strong constraints on the shape and redshift evolution of the stellar-to-halo mass relation (SHMR) from z = 0.2 to z = 1. At low stellar mass, we find that halo mass scales as M-h proportional to M-*(0.46) and that this scaling does not evolve significantly with redshift from z = 0.2 to z = 1. The slope of the SHMR rises sharply at M-* \textgreater 5 x 10(10)M(circle dot) and as a consequence, the stellar mass of a central galaxy becomes a poor tracer of its parent halo mass. We show that the dark-to-stellar ratio, Mh/M*, varies from low to high masses, reaching a minimum of Mh/M-* similar to 27 at M-* = 4.5 x 10(10) M-circle dot and M-h = 1.2 x 10(12) M-circle dot. This minimum is important for models of galaxy formation because it marks the mass at which the accumulated stellar growth of the central galaxy has been themost efficient. We describe the SHMR at this minimum in terms of the “ pivot stellarmass,” M-*(piv) the “pivot halo mass,” M-h(piv), and the “pivot ratio,” (M-h/M-*)(piv). Thanks to a homogeneous analysis of a single data set spanning a large redshift range, we report the first detection of mass downsizing trends for both M-h(piv) and M-*(piv) The pivot stellar mass decreases from M-*(piv) = 5.75 +/- 0.13x10(10) M-circle dot at z = 0.88 to M-*(piv) = 3.55 +/- 0.17x10(10) M-circle dot at z = 0.37. Intriguingly, however, the corresponding evolution of M-h(piv) leaves the pivot ratio constant with redshift at (M-h/M-*)(piv) similar to 27. We use simple arguments to show how this result raises the possibility that star formation quenching may ultimately depend on M-h/M-* and not simply onMh, as is commonly assumed. We show that simple models with such a dependence naturally lead to downsizing in the sites of star formation. Finally, we discuss the implications of our results in the context of popular quenching models, including disk instabilities and active galactic nucleus feedback.
547 citations
•
TL;DR: In this article, the authors studied the galaxy star formation rate as a function of environment using the SDSS EDR data and found that the suppression of the SFR starts to be noticeable at around 4 virial radii.
Abstract: We study the galaxy star formation rate (SFR) as a function of environment using the SDSS EDR data. We nd that the SFR is depressed in dense environments (clusters and groups) compared to the eld. We nd that the suppression of the SFR starts to be noticeable at around 4 virial radii. We nd no evidence for SF triggering as galaxies fall into the clusters. We also present a project to study these eects in cluster pairs systems where the eects of lamen ts and large scale structure may be noticeable.
546 citations
••
TL;DR: In this article, the authors analyzed the behavior of the gas-to-dust mass ratio (G/D) of local Universe galaxies over a wide metallicity range and investigated several explanations for the observed relation and scatter.
Abstract: Aims. The goal of this paper is to analyse the behaviour of the
gas-to-dust mass ratio (G/D) of local Universe galaxies over a wide metallicity range. We
especially focus on the low-metallicity part of the G/D vs metallicity relation and
investigate several explanations for the observed relation and scatter.Methods. We assembled a total of 126 galaxies, covering a 2 dex
metallicity range and with 30% of the sample with 12 + log(O/H)≤ 8.0. We homogeneously determined the dust
masses with a semi-empirical dust model including submm constraints. The atomic and
molecular gas masses have been compiled from the literature. We used two XCO scenarios to
estimate the molecular gas mass: the Galactic conversion factor, XCO,MW, and a
XCO that depends on the metallicity
XCO,Z
(∝Z-2). We
modelled the observed trend of the G/D with metallicity using two simple power laws (slope
of –1 and free) and a broken power law. Correlations with morphological type, stellar
masses, star formation rates, and specific star formation rates are also discussed. We
then compared the observed evolution of the G/D with predictions from several chemical
evolution models and explored different physical explanations for the observed scatter in
the G/D values.Results. We find that out of the five tested galactic parameters,
metallicity is the main physical property of the galaxy driving the observed G/D. The G/D
versus metallicity relation cannot be represented by a single power law with a slope of –1
over the whole metallicity range. The observed trend is steeper for metallicities lower
than ~8.0. A large scatter is
observed in the G/D values for a given metallicity: in metallicity bins of ~0.1 dex, the dispersion around the mean
value is ~0.37 dex. On
average, the broken power law reproduces the observed G/D best compared to the two power
laws (slope of –1 or free) and provides estimates of the G/D that are accurate to a factor
of 1.6. The good agreement of observed values of the G/D and its scatter with respect to
metallicity with the predicted values of the three tested chemical evolution models allows
us to infer that the scatter in the relation is intrinsic to galactic properties,
reflecting the different star formation histories, dust destruction efficiencies, dust
grain size distributions, and chemical compositions across the sample. Conclusions. Our results show that the chemical evolution of
low-metallicity galaxies, traced by their G/D, strongly depends on their local internal
conditions and individual histories. The large scatter in the observed G/D at a given
metallicity reflects the impact of various processes occurring during the evolution of a
galaxy. Despite the numerous degeneracies affecting them, disentangling these various
processes is now the next step.
543 citations
••
TL;DR: In this article, the authors present results from an IRAM Plateau de Bure millimetre-wave Interferometer (PdBI) survey for carbon monoxide (CO) emission towards radio-detected submillimetre galaxies (SMGs) with known optical and near-infrared spectroscopic redshifts.
Abstract: In this paper, we present results from an Institut de Radio Astronomie Millimetrique (IRAM) Plateau de Bure millimetre-wave Interferometer (PdBI) survey for carbon monoxide (CO) emission towards radio-detected submillimetre galaxies (SMGs) with known optical and near-infrared spectroscopic redshifts. Five sources in the redshift range z ∼ 1-3.5 were detected, nearly doubling the number of SMGs detected in CO. We summarize the properties of all 12 CO-detected SMGs, as well as six sources not detected in CO by our survey, and use this sample to explore the bulk physical properties of the submillimetre galaxy (SMG) population as a whole. The median CO line luminosity of the SMGs is = (3.8 ± 2.0) × 10 10 K km s -1 pc 2 . Using a CO-to-H 2 conversion factor appropriate for starburst galaxies, this corresponds to a molecular gas mass = (3.0 ± 1.6) x 10 10 M ○. within an ∼ 2 kpc radius, approximately 4 times greater than the most luminous local ultraluminous infrared galaxies (ULIRGs) but comparable to that of the most extreme high-redshift radio galaxies (HzRGs) and quasi-sellar objects (QSOs). The median CO FWHM linewidth is broad, (FWHM) = 780 ± 320 km s -1 , and the SMGs often have double-peaked line profiles, indicative of either a merger or a disc. From their median gas reservoirs (∼ 3 x 10 10 M ○. ) and star formation rates (≥ 700 M ○. yr -1 ), we estimate a lower limit on the typical gas-depletion time-scale of ≥ 40 Myr in SMGs. This is marginally below the typical age expected for the starbursts in SMGs and suggests that negative feedback processes may play an important role in prolonging the gas consumption time-scale. We find a statistically significant correlation between the far-infrared and CO luminosities of the SMGs, which extends the observed correlation for local ULIRGs to higher luminosities and higher redshifts. The non-linear nature of the correlation implies that SMGs have higher far-infrared to CO luminosity ratios and possibly higher star formation efficiencies (SFEs), than local ULIRGs. Assuming a typical CO source diameter of θ ∼ 0.5 arcsec (D ∼ 4kpc), we estimate a median dynamical mass of ≃ (1.2 ± 1.5) x 10 11 M ○. for the SMG sample. Both the total gas and stellar masses imply that SMGs are very massive systems, dominated by baryons in their central regions. The baryonic and dynamical properties of these systems mirror those of local giant ellipticals and are consistent with numerical simulations of the formation of the most massive galaxies. We have been able to impose a lower limit of ≥ 5 x 10 -6 Mpc -3 to the comoving number density of massive galaxies in the redshift range z ∼ 2-3.5, which is in agreement with results from recent spectroscopic surveys and the most recent model predictions.
543 citations