scholarly journals Evaluating hydrodynamical simulations with green valley galaxies

2020 ◽  
Author(s):  
J Angthopo ◽  
A Negri ◽  
I Ferreras ◽  
I G de la Rosa ◽  
C Dalla Vecchia ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Galaxy Formation ◽  
Seed Mass ◽  
Bimodal Distribution ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
M 10 ◽  
Sky Survey ◽  
Hydrodynamical Simulations

Abstract We test cosmological hydrodynamical simulations of galaxy formation regarding the properties of the Blue Cloud (BC), Green Valley (GV) and Red Sequence (RS), as measured on the 4000Å break strength vs stellar mass plane at z = 0.1. We analyse the RefL0100N1504 run of EAGLE and the TNG100 run of IllustrisTNG project, by comparing them with the Sloan Digital Sky Survey, while taking into account selection bias. Our analysis focuses on the GV, within stellar mass log  M⋆/M⊙ ≃ 10 − 11, selected from the bimodal distribution of galaxies on the Dn(4000) vs stellar mass plane, following Angthopo et al. methodology. Both simulations match the fraction of AGN in the green-valley. However, they over-produce quiescent GV galaxies with respect to observations, with IllustrisTNG yielding a higher fraction of quiescent GV galaxies than EAGLE. In both, GV galaxies have older luminosity-weighted ages with respect to the SDSS, while a better match is found for mass-weighted ages. We find EAGLE GV galaxies quench their star formation early, but undergo later episodes of star formation, matching observations. In contrast, IllustrisTNG GV galaxies have a more extended SFH, and quench more effectively at later cosmic times, producing the excess of quenched galaxies in GV compared with SDSS, based on the 4000Å break strength. These results suggest the AGN feedback subgrid physics, more specifically, the threshold halo mass for black hole input and the black hole seed mass, could be the primary cause of the over-production of quiescent galaxies found with respect to the observational constraints.

scholarly journals Interacting galaxies in the IllustrisTNG simulations - I: Triggered star formation in a cosmological context

2020 ◽  
Vol 494 (4) ◽  
pp. 4969-4985 ◽  
Author(s):  
David R Patton ◽  
Kieran D Wilson ◽  
Colin J Metrow ◽  
Sara L Ellison ◽  
Paul Torrey ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Density ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Massive Galaxies ◽  
Star Forming ◽  
Cosmological Context ◽  
Sky Survey ◽  
The Mean ◽  
Hydrodynamical Simulations

ABSTRACT We use the IllustrisTNG cosmological hydrodynamical simulations to investigate how the specific star formation rates (sSFRs) of massive galaxies (M* > 1010 M⊙) depend on the distance to their closest companions. We estimate sSFR enhancements by comparing with control samples that are matched in redshift, stellar mass, local density, and isolation, and we restrict our analysis to pairs with stellar mass ratios of 0.1 to 10. At small separations (∼15 kpc), the mean sSFR is enhanced by a factor of 2.0 ± 0.1 in the flagship (110.7 Mpc)3 simulation (TNG100-1). Statistically significant enhancements extend out to 3D separations of 280 kpc in the (302.6 Mpc)3 simulation (TNG300-1). We find similar trends in the EAGLE and Illustris simulations, although their sSFR enhancements are lower than those in TNG100-1 by about a factor of two. Enhancements in IllustrisTNG galaxies are seen throughout the redshift range explored (0 ≤ $z$ < 1), with the strength of the enhancements decreasing with increasing redshift for galaxies with close companions. In order to more closely compare with observational results, we separately consider 2D projected distances between galaxies in IllustrisTNG. We detect significant sSFR enhancements out to projected separations of 260 kpc in TNG300-1, with projection effects diluting the size of the enhancements by about 20 per cent below 50 kpc. We find similar sSFR enhancements in TNG100-1 and Sloan Digital Sky Survey galaxies, with enhancements extending out to projected separations of about 150 kpc for star-forming galaxies at $z$ < 0.2. Finally, by summing over all separations, we estimate that the presence of closest companions boosts the average sSFR of massive galaxies in TNG100-1 by 14.5 per cent.

scholarly journals Modelling the tightest relation between galaxy properties and dark matter halo properties from hydrodynamical simulations of galaxy formation

2020 ◽  
Vol 493 (3) ◽  
pp. 4453-4462
Author(s):  
Jian-hua He
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Strong Interactions ◽  
Circular Velocity ◽  
Sky Survey ◽  
Hydrodynamical Simulations ◽  
Robust Prediction

ABSTRACT We investigate how a property of a galaxy correlates most tightly with a property of its host dark matter halo, using state-of-the-art hydrodynamical simulations of galaxy formation: EAGLE, Illustris, and IllustrisTNG. Unlike most of the previous work, our analyses focus on all types of galaxies, including both central and satellite galaxies. We find that the stellar mass of a galaxy at the epoch of the peak circular velocity with an evolution correction gives the tightest such correlation to the peak circular velocity Vpeak of the galaxy’s underling dark matter halo. The evolution of galaxy stellar mass reduces rather than increases scatter in such a relation. We also find that one major source of scatter comes from star stripping due to the strong interactions between galaxies. Even though, we show that the size of scatter predicted by hydrodynamical simulations has a negligible impact on the clustering of dense Vpeak-selected subhalo from simulations, which suggests that even the simplest subhalo abundance matching (SHAM), without scatter and any additional free parameter, can provide a robust prediction of galaxy clustering that can agree impressively well with the observations from the Sloan Digital Sky Survey (SDSS) main galaxy survey.

scholarly journals How dark are filaments in the cosmic web?

2020 ◽  
Vol 498 (3) ◽  
pp. 3158-3170
Author(s):  
Tianyi Yang ◽  
Michael J Hudson ◽  
Niayesh Afshordi
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
Mass Fractions ◽  
The Masses ◽  
Red Galaxies

ABSTRACT The cold dark matter model predicts that dark matter haloes are connected by filaments. Direct measurements of the masses and structure of these filaments are difficult, but recently several studies have detected these dark-matter-dominated filaments using weak lensing. Here we study the efficiency of galaxy formation within the filaments by measuring their total mass-to-light ratios and stellar mass fractions. Specifically, we stack pairs of luminous red galaxies (LRGs) with a typical separation on the sky of 8 h−1 Mpc. We stack background galaxy shapes around pairs to obtain mass maps through weak lensing, and we stack galaxies from the Sloan Digital Sky Survey to obtain maps of light and stellar mass. To isolate the signal from the filament, we construct two matched catalogues of physical and non-physical (projected) LRG pairs, with the same distributions of redshift and separation. We then subtract the two stacked maps. Using LRG pair samples from the Baryon Oscillation Spectroscopic Survey at two different redshifts, we find that the evolution of the mass in filament is consistent with the predictions from perturbation theory. The filaments are not entirely dark: Their mass-to-light ratios (M/L = 351 ± 137 in solar units in the rband) and stellar mass fractions (Mstellar/M = 0.0073 ± 0.0030) are consistent with the cosmic values (and with their redshift evolutions).

scholarly journals Comparison of Composite and Star-forming Early-type Galaxies

2021 ◽  
Vol 163 (1) ◽  
pp. 28
Author(s):  
Yu-Zhong Wu
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Massive Galaxies ◽  
Star Forming ◽  
Sky Survey ◽  
Excitation Mechanisms ◽  
Stellar Masses ◽  
Evolution Scheme

Abstract I assemble 4684 star-forming early-type galaxies (ETGs) and 2011 composite ETGs (located in the composite region on the BPT diagram) from the catalog of the Sloan Digital Sky Survey Data Release 7 MPA-JHU emission-line measurements. I compare the properties of both ETG samples and investigate their compositions, stellar masses, specific star formation rates (sSFRs), and excitation mechanisms. Compared with star-forming ETGs, composite ETGs have higher stellar mass and lower sSFR. In the stellar mass and u − r color diagram, more than 60% of star-forming ETGs and composite ETGs are located in the green valley, showing that the two ETG samples may have experienced star formation and that ∼17% of star-forming ETGs lie in the blue cloud, while ∼30% of composite ETGs lie in the red sequence. In the [N II]/Hα versus EWHα (the Hα equivalent width) diagram, all star-forming ETGs and most of the composite ETGs are located in the star-forming galaxy region, and composite ETGs have lower EWHα than their counterparts. We show the relations between 12+log(O/H) and log(N/O) for both ETG samples, and suggest that nitrogen production of some star-forming ETGs can be explained by the evolution scheme of Coziol et al., while the prodution of composite ETGs may be a consequence of the inflowing of metal-poor gas and these more evolved massive galaxies.

scholarly journals Galaxy pairs in the Sloan Digital Sky Survey – XIV. Galaxy mergers do not lie on the fundamental metallicity relation

2020 ◽  
Vol 494 (3) ◽  
pp. 3469-3480 ◽  
Author(s):  
Sebastián Bustamante ◽  
Sara L Ellison ◽  
David R Patton ◽  
Martin Sparre
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Formation Rate ◽  
Local Environment ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Galaxy Mergers ◽  
Star Forming ◽  
Sky Survey ◽  
Evolutionary Phase

ABSTRACT In recent observational studies, star-forming galaxies have been shown to follow a relation often dubbed the fundamental metallicity relation (FMR). This relation links the stellar mass of a galaxy with its star formation rate (SFR) and its gas-phase metallicity. Specifically, the FMR predicts that galaxies, at a given stellar mass, exhibit lower metallicities for higher SFRs. This trend is qualitatively consistent with observations of galaxy pairs, which have been robustly shown to experience increasing gas-phase metallicity dilution and enhanced star formation activity with decreasing projected separation. In this work, we show that, despite the qualitative consistency with FMR expectations, the observed O/H dilution in galaxy pairs of the Sloan Digital Sky Survey is stronger than what is predicted by the FMR. We conclude that the evolutionary phase of galaxies interacting with companions is not encoded in the FMR, and thus, mergers constitute a clearly defined population of outliers. We find that galaxies in pairs are consistent with the FMR only when their separation is larger than 110 kpc. Finally, we also quantify the local environment of the pairs using the number of galaxy neighbours within 2 Mpc, N2, and the projected separation to the second closest galaxy, r2. We find that pairs are more sensitive to a second companion than to the local galaxy density, displaying less elevated SFRs with smaller values of r2.

scholarly journals Dark-ages reionization and galaxy formation simulation – XVIII. The high-redshift evolution of black holes and their host galaxies

2020 ◽  
Vol 494 (2) ◽  
pp. 2747-2759 ◽  
Author(s):  
Madeline A Marshall ◽  
Simon J Mutch ◽  
Yuxiang Qin ◽  
Gregory B Poole ◽  
J Stuart B Wyithe
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Galaxy Formation ◽  
High Redshift ◽  
Stellar Mass ◽  
Mass Relation ◽  
Host Galaxies ◽  
Black Hole Growth ◽  
Hydrodynamical Simulations ◽  
Hole Growth

ABSTRACT Correlations between black holes and their host galaxies provide insight into what drives black hole–host co-evolution. We use the Meraxes semi-analytic model to investigate the growth of black holes and their host galaxies from high redshift to the present day. Our modelling finds no significant evolution in the black hole–bulge and black hole–total stellar mass relations out to a redshift of 8. The black hole–total stellar mass relation has similar but slightly larger scatter than the black hole–bulge relation, with the scatter in both decreasing with increasing redshift. In our modelling, the growth of galaxies, bulges, and black holes are all tightly related, even at the highest redshifts. We find that black hole growth is dominated by instability-driven or secular quasar-mode growth and not by merger-driven growth at all redshifts. Our model also predicts that disc-dominated galaxies lie on the black hole–total stellar mass relation, but lie offset from the black hole–bulge mass relation, in agreement with recent observations and hydrodynamical simulations.

scholarly journals Clustering constraints on the relative sizes of central and satellite galaxies

2019 ◽  
Vol 489 (2) ◽  
pp. 1805-1819 ◽  
Author(s):  
Andrew Hearin ◽  
Peter Behroozi ◽  
Andrey Kravtsov ◽  
Benjamin Moster
Keyword(s):  
Size Dependence ◽  
Strong Support ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Modelling Techniques ◽  
Satellite Galaxies ◽  
Hydrodynamical Simulations ◽  
Analytic Models ◽  
Mass Dependent

ABSTRACT We empirically constrain how galaxy size relates to halo virial radius using new measurements of the size- and stellar mass-dependent clustering of galaxies in the Sloan Digital Sky Survey. We find that small galaxies cluster much more strongly than large galaxies of the same stellar mass. The magnitude of this clustering difference increases on small scales, and decreases with increasing stellar mass. Using forward-modelling techniques implemented in Halotools, we test an empirical model in which present-day galaxy size is proportional to the size of the virial radius at the time the halo reached its maximum mass. This simple model reproduces the observed size dependence of galaxy clustering in striking detail. The success of this model provides strong support for the conclusion that satellite galaxies have smaller sizes relative to central galaxies of the same halo mass. Our findings indicate that satellite size is set prior to the time of infall, and that a remarkably simple, linear size–virial radius relation emerges from the complex physics regulating galaxy size. We make quantitative predictions for future measurements of galaxy–galaxy lensing, including dependence upon size, scale, and stellar mass, and provide a scaling relation of the ratio of mean sizes of satellites and central galaxies as a function of their halo mass that can be used to calibrate hydrodynamical simulations and semi-analytic models.

scholarly journals Evolution of the distribution of stellar mass and light since redshift of unity

2012 ◽  
Vol 8 (S295) ◽  
pp. 121-124
Author(s):  
Cheng Li
Keyword(s):  
Dark Matter ◽  
Spatial Scale ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Local Universe ◽  
Sky Survey ◽  
Fluctuation Amplitude ◽  
Better Than ◽  
Environmental Dependence

AbstractWe use data from the Sloan Digital Sky Survey (SDSS) and the DEEP2 survey to characterize the distribution of stellar mass and light of galaxies in the low-redshift and z = 1 Universe. We investigate the clustering bias of stellar mass and light by comparing these to projected autocorrelations of dark matter estimated from the Millennium Simulations (MS). All of the autocorrelation and bias functions show systematic trends with spatial scale and waveband, which are impressively similar at the two redshifts. This shows that the well-established environmental dependence of stellar populations in the local Universe is already in place at z = 1. The recent MS-based galaxy formation simulation of Guo et al. (2011) reproduces the scale-dependent clustering of luminosity to an accuracy better than 30% in all bands and at both redshifts, but substantially overpredicts mass autocorrelations at separations below ~ 2 Mpc. Further comparison of the shapes of our stellar mass bias functions with those predicted by the model suggests that both the SDSS and DEEP2 data prefer a fluctuation amplitude of σ8 ~ 0.8 rather than the σ8 = 0.9 assumed by the MS.

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