scholarly journals The cosmic atomic hydrogen mass density as a function of mass and galaxy hierarchy from spectral stacking

2020 ◽  
Vol 493 (2) ◽  
pp. 1587-1595 ◽  
Author(s):  
Wenkai Hu ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Lister Staveley-Smith ◽  
Claudia del P Lagos ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Atomic Hydrogen ◽  
Mass Density ◽  
Theoretical Models ◽  
Theoretical Work ◽  
Sloan Digital Sky Survey ◽  
Analytical Models ◽  
Local Universe ◽  
Satellite Galaxies ◽  
Stellar Masses

ABSTRACT We use spectral stacking to measure the contribution of galaxies of different masses and in different hierarchies to the cosmic atomic hydrogen (H i) mass density in the local Universe. Our sample includes 1793 galaxies at z < 0.11 observed with the Westerbork Synthesis Radio Telescope, for which Sloan Digital Sky Survey spectroscopy and hierarchy information are also available. We find a cosmic H i mass density of $\Omega _{\rm H\, \small {I} } = (3.99 \pm 0.54)\times 10^{-4} \, h_{70}^{-1}$ at 〈 z〉 = 0.065. For the central and satellite galaxies, we obtain $\Omega _{\rm H\, {\small {I}}}$ of $(3.51 \pm 0.49)\times 10^{-4} \, h_{70}^{-1}$ and $(0.90 \pm 0.16)\times 10^{-4} \, h_{70}^{-1}$, respectively. We show that galaxies above and below stellar masses of ∼109.3 M⊙ contribute in roughly equal measure to the global value of $\Omega _{\rm H\, \small {I} }$. While consistent with estimates based on targeted H i surveys, our results are in tension with previous theoretical work. We show that these differences are, at least partly, due to the empirical recipe used to set the partition between atomic and molecular hydrogen in semi-analytical models. Moreover, comparing our measurements with the cosmological semi-analytic models of galaxy formation Shark and GALFORM reveals gradual stripping of gas via ram pressure works better to fully reproduce the properties of satellite galaxies in our sample than strangulation. Our findings highlight the power of this approach in constraining theoretical models and confirm the non-negligible contribution of massive galaxies to the H i mass budget of the local Universe.

scholarly journals The frequency of very young galaxies in the local Universe – II. The view from SDSS spectra

2019 ◽  
Vol 492 (2) ◽  
pp. 1791-1811 ◽  
Author(s):  
Gary A Mamon ◽  
Marina Trevisan ◽  
Trinh X Thuan ◽  
Anna Gallazzi ◽  
Romeel Davé
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Analytical Models ◽  
Local Universe ◽  
M 10 ◽  
Hydrodynamical Simulation ◽  
Spectral Models ◽  
Galaxy Sample ◽  
Stellar Masses ◽  
Star Formation Histories

ABSTRACT Only a handful of galaxies in the local Universe appear to be very young. We estimate the fraction of very young galaxies (VYGs), defined as those with more than half their stellar masses formed within the last Gyr. We fit non-parametric star formation histories (SFHs) to ∼280 000 galaxy spectra from a flux- and volume-limited subsample of the Main Galaxy Sample (MGS) of the SDSS, which is also complete in mass-to-light ratio, thus properly accounting for passive galaxies of a given mass. The VYG fractions decrease with increasing galaxy stellar mass, from ∼50 per cent at $m = 10^8\, {\rm M}_{\odot }$ to ∼0.1 per cent at $m = 10^{11.5}\, {\rm M}_{\odot }$, with differences of up to 1 dex between the different spectral models used to estimate the SFH and on how we treat aperture effects. But old stellar populations may hide in our VYGs despite our conservative VYG sample built with galaxies that are globally bluer than within the region viewed by the SDSS fibre. The VYG fractions versus mass decrease more gradually compared to the Tweed et al. predictions using analytical and semi-analytical models of galaxy formation, but agree better with the SIMBA hydrodynamical simulation. These discrepancies highlight the usefulness of VYGs in constraining the strong uncertainties in both galaxy formation models and spectral modelling of galaxy SFHs. Given the lognormal cosmic SFH, these mean VYG fractions suggest that galaxies above $10^8\, \rm M_\odot$ undergo at most four major starbursts on average.

scholarly journals The Bimodality of Galaxy Populations Revisited Through Spectral Synthesis

2006 ◽  
Vol 2 (S235) ◽  
pp. 139-139
Author(s):  
L. Sodré ◽  
A. Mateus ◽  
R. Cid Fernandes ◽  
G. Stasińska ◽  
W. Schoenell ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Spectral Synthesis ◽  
Synthesis Method ◽  
Local Universe ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Stellar Masses

AbstractWe revisit the bimodality of the galaxy population seen in the local universe. We address this issue in terms of physical properties of galaxies, such as mean stellar ages and stellar masses, derived from the application of a spectral synthesis method to galaxy spectra from the SDSS. We show that the mean light-weighted stellar age of galaxies presents the best description of the bimodality seen in the galaxy population. The stellar mass has an additional role since most of the star-forming galaxies present in the local universe are low-mass galaxies. Our results give support to the existence of a ‘downsizing’ in galaxy formation, where nowadays massive galaxies tend to have stellar populations older than those found in less massive objects.

scholarly journals Satellite galaxies in the Illustris-1 simulation: anisotropic locations around relatively isolated hosts

2019 ◽  
Vol 489 (1) ◽  
pp. 459-469 ◽  
Author(s):  
Tereasa G Brainerd ◽  
Masaya Yamamoto
Keyword(s):  
Dark Matter ◽  
Mass Density ◽  
Stellar Mass ◽  
Stellar Surface ◽  
Surface Mass ◽  
Degree Of Anisotropy ◽  
Surface Mass Density ◽  
The Mean ◽  
Satellite Galaxies ◽  
Stellar Masses

ABSTRACT We investigate the locations of satellite galaxies in the z = 0 redshift slice of the hydrodynamical Illustris-1 simulation. As expected from previous work, the satellites are distributed anisotropically in the plane of the sky, with a preference for being located near the major axes of their hosts. Due to misalignment of mass and light within the hosts, the degree of anisotropy is considerably less when satellite locations are measured with respect to the hosts’ stellar surface mass density than when they are measured with respect to the hosts’ dark matter surface mass density. When measured with respect to the hosts’ dark matter surface mass density, the mean satellite location depends strongly on host stellar mass and luminosity, with the satellites of the faintest, least massive hosts showing the greatest anisotropy. When measured with respect to the hosts’ stellar surface mass density, the mean satellite location is essentially independent of host stellar mass and luminosity. In addition, the satellite locations are largely insensitive to the amount of stellar mass used to define the hosts’ stellar surface mass density, as long as at least 50–70 per cent of the hosts’ total stellar mass is used. The satellite locations are dependent upon the stellar masses of the satellites, with the most massive satellites having the most anisotropic distributions.

scholarly journals What has quenched the massive spiral galaxies?

2020 ◽  
Vol 496 (1) ◽  
pp. L116-L121
Author(s):  
Yu Luo ◽  
Zongnan Li ◽  
Xi Kang ◽  
Zhiyuan Li ◽  
Peng Wang
Keyword(s):  
Black Holes ◽  
Spiral Galaxies ◽  
Theoretical Models ◽  
Mass Range ◽  
Sloan Digital Sky Survey ◽  
Analytical Models ◽  
Gas Content ◽  
Quenching Mechanism ◽  
Massive Black Holes ◽  
Hydrodynamical Simulations

ABSTRACT Quenched massive spiral galaxies have attracted great attention recently, as more data are available to constrain their environment and cold gas content. However, the quenching mechanism is still uncertain, as it depends on the mass range and baryon budget of the galaxy. In this letter, we report the identification of a rare population of very massive, quenched spiral galaxies with stellar mass ≳1011 M⊙ and halo mass ≳1013 M⊙ from the Sloan Digital Sky Survey at redshift z ∼ 0.1. Our CO observations using the IRAM (Institute for Radio Astronomy in the Millimeter Range) 30-m telescope show that these galaxies contain only a small amount of molecular gas. Similar galaxies are also seen in the state-of-the-art semi-analytical models and hydrodynamical simulations. It is found from these theoretical models that these quenched spiral galaxies harbour massive black holes, suggesting that feedback from the central black holes has quenched these spiral galaxies. This quenching mechanism seems to challenge the popular scenario of the co-evolution between massive black holes and massive bulges.

scholarly journals Global H i asymmetries in IllustrisTNG: a diversity of physical processes disturb the cold gas in galaxies

2020 ◽  
Vol 499 (4) ◽  
pp. 5205-5219
Author(s):  
Adam B Watts ◽  
Chris Power ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Adam R H Stevens
Keyword(s):  
Galaxy Formation ◽  
Atomic Hydrogen ◽  
Physical Processes ◽  
Low Velocity ◽  
Ram Pressure ◽  
Asymmetric Shape ◽  
Satellite Galaxies ◽  
Large Groups ◽  
Disc Galaxies ◽  
Cold Gas

ABSTRACT Observations of the cold neutral atomic hydrogen (H i) in and around disc galaxies have revealed that spatial and kinematic asymmetries are common place, and are reflected in the global H i spectra. We use the TNG100 box from the IllustrisTNG suite of cosmological simulations to study the conditions under which these asymmetries may arise in current theoretical galaxy formation models. We find that more than 50 per cent of the sample has at least a 10 per cent difference in integrated flux between the high- and low-velocity half of the spectrum, thus the typical TNG100 galaxy has an H i profile that is not fully symmetric. We find that satellite galaxies are a more asymmetric population than centrals, consistent with observational results. Using halo mass as a proxy for environment, this trend appears to be driven by the satellite population within the virial radius of haloes more massive than 1013 M⊙, typical of medium/large groups. We show that, while the excess of H i asymmetry in group satellites is likely driven by ram pressure, the bulk of the asymmetric H i profiles observed in TNG100 are driven by physical processes able to affect both the central and satellite populations. Our results highlight how asymmetries are not driven solely by environment, and multiple physical processes can produce the same asymmetric shape in global H i spectra.

scholarly journals The atomic hydrogen content of the post-reionization Universe

2020 ◽  
Vol 493 (4) ◽  
pp. 5434-5455 ◽  
Author(s):  
Marta Spinelli ◽  
Anna Zoldan ◽  
Gabriella De Lucia ◽  
Lizhi Xie ◽  
Matteo Viel
Keyword(s):  
Galaxy Formation ◽  
Shot Noise ◽  
Atomic Hydrogen ◽  
Mass Function ◽  
Limiting Factor ◽  
History Plays ◽  
Local Universe ◽  
Intensity Mapping ◽  
The One ◽  
Halo Occupation Distribution

ABSTRACT We present a comprehensive analysis of atomic hydrogen (H i) properties using a semi-analytical model of galaxy formation and N-body simulations covering a large cosmological volume at high resolution. We examine the H i mass function and the H i density, characterizing both their redshift evolution and their dependence on hosting halo mass. We analyse the H i content of dark matter haloes in the local Universe and up to redshift z = 5, discussing the contribution of different galaxy properties. We find that different assembly history plays a crucial role in the scatter of this relation. We propose new fitting functions useful for constructing mock H i maps with halo occupation distribution techniques. We investigate the H i clustering properties relevant for future 21 cm intensity mapping (IM) experiments, including the H i bias and the shot-noise level. The H i bias increases with redshift and it is roughly flat on the largest scales probed. The scale dependence is found at progressively larger scales with increasing redshift, apart from a dip feature at z = 0. The shot-noise values are consistent with the ones inferred by independent studies, confirming that shot noise will not be a limiting factor for IM experiments. We detail the contribution from various galaxy properties on the H i power spectrum and their relation to the halo bias. We find that H i poor satellite galaxies play an important role at the scales of the one-halo term. Finally, we present the 21 cm signal in redshift space, a fundamental prediction to be tested against data from future radio telescopes such as Square Kilometre Array.

scholarly journals Constraining scatter in the stellar mass–halo mass relation for haloes less massive than the Milky Way

2019 ◽  
Vol 488 (4) ◽  
pp. 4916-4925 ◽  
Author(s):  
Magdelena Allen ◽  
Peter Behroozi ◽  
Chung-Pei Ma
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Distribution Functions ◽  
Sloan Digital Sky Survey ◽  
Data Sets ◽  
Mass Relation ◽  
Velocity Distribution Functions ◽  
Halo Masses ◽  
Stellar Masses

ABSTRACT Most galaxies are hosted by massive, invisible dark matter haloes, yet little is known about the scatter in the stellar mass–halo mass relation for galaxies with host halo masses Mh ≤ 1011M⊙. Using mock catalogues based on dark matter simulations, we find that two observable signatures are sensitive to scatter in the stellar mass–halo mass relation even at these mass scales; i.e. conditional stellar mass functions and velocity distribution functions for neighbouring galaxies. We compute these observables for  179,373 galaxies in the Sloan Digital Sky Survey (SDSS) with stellar masses M* > 109 M⊙ and redshifts 0.01 < z < 0.307. We then compare to mock observations generated from the Bolshoi-Planck dark matter simulation for stellar mass–halo mass scatters ranging from 0 to 0.6 dex. The observed results are consistent with simulated results for most values of scatter (<0.6 dex), and SDSS statistics are insufficient to provide firm constraints. However, this method could provide much tighter constraints on stellar mass–halo mass scatter in the future if applied to larger data sets, especially the anticipated Dark Energy Spectroscopic Instrument Bright Galaxy Survey. Constraining the value of scatter could have important implications for galaxy formation and evolution.

scholarly journals Galaxies on Sub-Galactic Scales

2012 ◽  
Vol 29 (4) ◽  
pp. 383-394 ◽  
Author(s):  
Helmut Jerjen
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Near Field ◽  
Sloan Digital Sky Survey ◽  
Matter Theory ◽  
Satellite Galaxies ◽  
Star Formation Histories

AbstractThe Sloan Digital Sky Survey has been immensely successful in detecting new Milky Way satellite galaxies over the past seven years. It was instrumental in finding examples of the least luminous galaxies we know in the Universe, uncovering apparent inconsistencies between cold dark matter theory and dwarf galaxy properties, providing first evidence for a possible lower mass limit for dark matter halos in visible galaxies, and reopening the discussion about the building block scenario for the Milky Way halo. Nonetheless, these results are still drawn only from a relatively small number of galaxies distributed over an area covering about 29% of the sky, which leaves us currently with more questions than answers. The study of these extreme stellar systems is a multi-parameter problem: ages, metallicities, star formation histories, dark matter contents, population fractions and spatial distributions must be determined. Progress in the field is discussed and attention drawn to some of the limitations that currently hamper our ability to fully understand the phenomenon of the ‘ultra-faint dwarf galaxy’. In this context, the Stromlo Milky Way Satellite Survey represents a new initiative to systematically search and scrutinize optically elusive Milky Way satellite galaxies in the Southern hemisphere. In doing so, the program aims at investigating some of the challenging questions in stellar evolution, galaxy formation and near-field cosmology.

scholarly journals Galaxy sizes and the galaxy–halo connection – I. The remarkable tightness of the size distributions

2019 ◽  
Vol 492 (2) ◽  
pp. 1671-1690 ◽  
Author(s):  
Lorenzo Zanisi ◽  
Francesco Shankar ◽  
Andrea Lapi ◽  
Nicola Menci ◽  
Mariangela Bernardi ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Theoretical Models ◽  
Momentum Conservation ◽  
Empirical Models ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Size Distributions ◽  
Massive Galaxies ◽  
Structural Assembly ◽  
Semi Empirical

ABSTRACT The mass and structural assembly of galaxies is a matter of intense debate. Current theoretical models predict the existence of a linear relationship between galaxy size (Re) and the host dark matter halo virial radius (Rh). By making use of semi-empirical models compared to the size distributions of central galaxies from the Sloan Digital Sky Survey, we provide robust constraints on the normalization and scatter of the Re−Rh relation. We explore the parameter space of models in which the Re−Rh relation is mediated by either the spin parameter or the concentration of the host halo, or a simple constant the nature of which is in principle unknown. We find that the data require extremely tight relations for both early-type and late-type galaxies (ETGs, LTGs), especially for more massive galaxies. These constraints challenge models based solely on angular momentum conservation, which predict significantly wider distributions of galaxy sizes and no trend with stellar mass, if taken at face value. We discuss physically motivated alterations to the original models that bring the predictions into better agreement with the data. We argue that the measured tight size distributions of SDSS disc galaxies can be reproduced by semi-empirical models in which the Re−Rh connection is mediated by the stellar specific angular momenta jstar. We find that current cosmological models of galaxy formation broadly agree with our constraints for LTGs, and justify the strong link between Re and jstar that we propose, however the tightness of the Re−Rh relation found in such ab initio theoretical models for ETGs is in tension with our semi-empirical findings.

scholarly journals Dwarf Cosmology with the Stromlo Missing Satellites Survey

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Helmut Jerjen
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Primary Objective ◽  
Sloan Digital Sky Survey ◽  
Galaxy Formation And Evolution ◽  
National University ◽  
Formation And Evolution ◽  
Satellite Galaxies

The standard Lambda Cold Dark Matter model is considered to be a triumph of theoretical astrophysics but observations of the Milky Way and its system of satellite galaxies irresistibly signal that theory is incomplete on galactic and subgalactic scales. The Stromlo Missing Satellites (SMS) Survey is a critical endeavor to investigate at what level predictions of CDM cosmology are consistent with the observed matter distribution in the Milky Way halo. It will be the deepest, most extended search for optically elusive satellite galaxies to date, covering 20 000 square degrees of sky. The international SMS Survey collaboration will exploit 150 TB of CCD images in six filters acquired by the new SkyMapper telescope of the Australian National University over the next five years, expecting on completion photometric limits 0.5–1.0 mag fainter than the Sloan Digital Sky Survey. The primary objective of the program is to characterise the baryonic and dark matter components of a complete sample of MW satellites in the Southern hemisphere to provide stringent observational constraints for improving our understanding of how the Milky Way formed and what physical processes governed galaxy formation and evolution in general.

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