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 influence of environment on satellite galaxies in the GAEA semi-analytic model

2020 ◽  
Vol 498 (3) ◽  
pp. 4327-4344 ◽  
Author(s):  
Lizhi Xie ◽  
Gabriella De Lucia ◽  
Michaela Hirschmann ◽  
Fabio Fontanot
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Analytic Model ◽  
Gas Stripping ◽  
Hot Gas ◽  
Ram Pressure ◽  
Low Mass ◽  
Quenching Mechanisms ◽  
Satellite Galaxies ◽  
Cold Gas

ABSTRACT Reproducing the observed quenched fraction of satellite galaxies has been a long-standing issue for galaxy formation models. We modify the treatment of environmental effects in our state-of-the-art GAlaxy Evolution and Assembly (GAEA) semi-analytic model to improve our modelling of satellite galaxies. Specifically, we implement gradual stripping of hot gas, ram-pressure stripping of cold gas, and an updated algorithm to account for angular momentum exchanges between the gaseous and stellar disc components of model galaxies. Our updated model predicts quenched fractions that are in good agreement with local observational measurements for central and satellite galaxies, and their dependencies on stellar mass and halo mass. We also find consistency between model predictions and observational estimates of quenching times for satellite galaxies, H i, H2 fractions of central galaxies, and deficiencies of H i, H2, SFR of galaxies in cluster haloes. In the framework of our updated model, the dominant quenching mechanisms are hot gas stripping for low-mass satellite galaxies, and AGN feedback for massive satellite galaxies. The ram-pressure stripping of cold gas only affects the quenched fraction in massive haloes with Mh > 1013.5 M⊙, but is needed to reproduce the observed H i deficiencies.

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 Effects of environment on the properties of cluster galaxies via ram pressure stripping

2009 ◽  
Vol 5 (H15) ◽  
pp. 294-294
Author(s):  
T. E. Tecce ◽  
S. A. Cora ◽  
P. B. Tissera ◽  
M. G. Abadi
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Galaxy Formation ◽  
Gas Content ◽  
Analytic Model ◽  
Cluster Galaxies ◽  
Ram Pressure ◽  
Cold Gas

AbstractWe study the effect of ram pressure stripping (RPS) on the colours, cold gas content and star formation of galaxies in clusters, using a combination of N-Body/SPH simulations of galaxy clusters and a semi-analytic model of galaxy formation that includes the effect of RPS.

scholarly journals Baryonic Dark Halos: a model with MACHOS and cold gas globules

1996 ◽  
Vol 171 ◽  
pp. 167-170
Author(s):  
Ortwin Gerhard ◽  
Joseph Silk
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Active Role ◽  
Galaxy Formation And Evolution ◽  
Substellar Objects ◽  
Formation And Evolution ◽  
Cold Gas

The dark matter in the halos of galaxies may well be baryonic, and much of the mass within them could be in the form of clusters of substellar objects within which are embedded cold gas globules. Such halos might play an active role in galaxy formation and evolution.

scholarly journals The atomic hydrogen/molecular cloud association: an unavoidable relationship

1991 ◽  
Vol 147 ◽  
pp. 37-40
Author(s):  
G. Joncas
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Clouds ◽  
Large Scale ◽  
Young Stars ◽  
Physical Processes ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions ◽  
The Impact

The presence of HI in the interstellar medium is ubiquitous. HI is the principal actor in the majority of the physical processes at work in our Galaxy. Restricting ourselves to the topics of this symposium, atomic hydrogen is involved with the formation of molecular clouds and is one of the byproducts of their destruction by young stars. HI has different roles during a molecular cloud's life. I will discuss here a case of coexisting HI and H2 at large scale and the origin of HI in star forming regions. For completeness' sake, it should be mentionned that there are at least three other aspects of HI involvement: HI envelopes around molecular clouds, the impact of SNRs (see work on IC 443), and the role of HI in quiescent dark clouds (see van der Werf's work).

scholarly journals Modeling dust in a universe of galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 44-54
Author(s):  
Desika Narayanan ◽  
Qi Li ◽  
Romeel Davé ◽  
Charlie Conroy ◽  
Benjamin D. Johnson ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
State Of The Art ◽  
High Redshift ◽  
Mass Function ◽  
Physical Processes ◽  
Dust Mass

AbstractIn this invited talk, we discuss the physics of the lifecycle of dust in the context of galaxy formation simulations. After outlining the basic physical processes, we apply algorithms for the formation, growth, and destruction of dust in the ISM to a state-of-the-art cosmological simulation to develop a model for the evolution of the dust to gas and dust to metals ratios in galaxies. We show that while modern simulations are able to match the observed dust mass function at redshift z = 0, most models underpredict the observed mass function at high-redshift (z = 2). We then show the power of these techniques by expanding our model to include a spectrum of dust sizes, and make initial predictions for extinction laws in local galaxies.

scholarly journals Structural diversity of disc galaxies originating in the cold gas inflow from cosmic webs

2020 ◽  
Vol 494 (1) ◽  
pp. L37-L41
Author(s):  
Masafumi Noguchi
Keyword(s):  
High Redshift ◽  
Morphological Diversity ◽  
Structural Diversity ◽  
High Mass ◽  
Cold Flow ◽  
Hubble Sequence ◽  
The Galaxy ◽  
Gas Accretion ◽  
Disc Galaxies ◽  
Cold Gas

ABSTRACT Disc galaxies show a large morphological diversity with varying contribution of three major structural components: thin discs, thick discs, and central bulges. Dominance of bulges increases with the galaxy mass (Hubble sequence), whereas thick discs are more prominent in lower mass galaxies. Because galaxies grow with the accretion of matter, this observed variety should reflect diversity in accretion history. On the basis of the prediction by the cold-flow theory for galactic gas accretion and inspired by the results of previous studies, we put a hypothesis that associates different accretion modes with different components. Namely, thin discs form as the shock-heated hot gas in high-mass haloes gradually accretes to the central part, thick discs grow by the direct accretion of cold gas from cosmic webs when the halo mass is low, and finally bulges form by the inflow of cold gas through the shock-heated gas in high-redshift massive haloes. We show that this simple hypothesis reproduces the mean observed variation of galaxy morphology with the galaxy mass. This scenario also predicts that thick discs are older and poorer in metals than thin discs, in agreement with the currently available observations.

scholarly journals VORTEX IN AXION CONDENSATE AS A DARK MATTER HALO

2010 ◽  
Vol 19 (11) ◽  
pp. 1843-1855 ◽  
Author(s):  
JAKUB MIELCZAREK ◽  
TOMASZ STACHOWIAK ◽  
MAREK SZYDŁOWSKI
Keyword(s):  
Galaxy Formation ◽  
Vortex Formation ◽  
Analytical Models ◽  
Dark Matter Halo ◽  
Low Velocity ◽  
Single Vortex ◽  
Angular Momenta ◽  
The Galaxy ◽  
De Broglie Wavelength ◽  
Present Understanding

We study the possibility of the vortex formation in axion condensates on the galactic scale. Such vortices can occur as a result of global rotation of the early universe. We study analytical models of vortices and calculate exemplary galaxy rotation curves. Depending on the setup it is possible to obtain a variety of shapes which give a good qualitative agreement with observational results. However, as we show, the extremely low velocity dispersions of the axion velocities are required to form the single vortex on the galactic scales. We find that the required velocity dispersion is of the order of σ≈10-12 ms-1. This is much smaller that predicted within the present understanding of the axion physics. The vortices in axion condensate can however be formed on the much smaller scales and give seeds to the galaxy formation and to their angular momenta. On the other hand, the vortices can be formed on the galactic scales, but only if the mass of the axion-like particles is of the order of 10-30 eV. In this case, the particle de Broglie wavelength is comparable with the galactic diameter. This condition must be fulfilled in order to keep the coherence of the quantum condensate on galactic scales.

Radial resolved galaxy disks models based on semi-analytic models of galaxy formation

2019 ◽  
Vol 15 (S341) ◽  
pp. 273-274
Author(s):  
Jian Fu
Keyword(s):  
Galaxy Formation ◽  
Scaling Relations ◽  
Chemical Enrichment ◽  
Galaxy Disk ◽  
Analytic Models ◽  
Cold Gas

AbstractWe show our work on the L-Galaxies semi-analytic models of galaxy formation, which includes the radial resolved distribution of star, gas, SFR and metallicity on each galaxy disk. The newest version of the codes include the H22-to-HI gas transition prescriptions and the chemical enrichment of various elements. Our revised model can give results on cold gas components, radial metallicity gradients and scaling relations, which can fit the recent observations.

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