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Category: galaxy formation and evolution (Page 1 of 3)

Terrazas et al. (2020)

The relationship between black hole mass and galaxy properties: examining the black hole feedback model in IllustrisTNG

by
Terrazas, Bryan A.; Bell, Eric F.; Pillepich, Annalisa; Nelson, Dylan; Somerville, Rachel S.; Genel, Shy; Weinberger, Rainer; Habouzit, Mélanie; Li, Yuan; Hernquist, Lars; Vogelsberger, Mark

abstract
Supermassive black hole feedback is thought to be responsible for the lack of star formation, or quiescence, in a significant fraction of galaxies. We explore how observable correlations between the specific star formation rate (sSFR), stellar mass (Mstar), and black hole mass (MBH) are sensitive to the physics of black hole feedback in a galaxy formation model. We use the IllustrisTNG simulation suite, specifically the TNG100 simulation and 10 model variations that alter the parameters of the black hole model. Focusing on central galaxies at z = 0 with Mstar > 1010 M, we find that the sSFR of galaxies in IllustrisTNG decreases once the energy from black hole kinetic winds at low accretion rates becomes larger than the gravitational binding energy of gas within the galaxy stellar radius. This occurs at a particular MBH threshold above which galaxies are found to sharply transition from being mostly star forming to mostly quiescent. As a result of this behaviour, the fraction of quiescent galaxies as a function of Mstar is sensitive to both the normalization of the MBH-Mstar relation and the MBH threshold for quiescence in IllustrisTNG. Finally, we compare these model results to observations of 91 central galaxies with dynamical MBH measurements with the caveat that this sample is not representative of the whole galaxy population. While IllustrisTNG reproduces the observed trend that quiescent galaxies host more massive black holes, the observations exhibit a broader scatter in MBH at a given Mstar and show a smoother decline in sSFR with MBH.

published in
Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 2, p.1888-1906, April 2020

links to paper
[ADS][arXiv]

Truong et al. (2020)

X-ray signatures of black hole feedback: hot galactic atmospheres in IllustrisTNG and X-ray observations

by
Truong, Nhut; Pillepich, Annalisa; Werner, Norbert; Nelson, Dylan; Lakhchaura, Kiran; Weinberger, Rainer; Springel, Volker; Vogelsberger, Mark; Hernquist, Lars

abstract
Hot gaseous atmospheres that permeate galaxies and extend far beyond their stellar distribution, where they are commonly referred to as the circumgalactic medium, imprint important information about feedback processes powered by the stellar populations of galaxies and their central supermassive black holes (SMBHs). In this work, we study the properties of this hot X-ray emitting medium using the IllustrisTNG cosmological simulations. We analyse their mock X-ray spectra, obtained from the diffuse and metal-enriched gas in TNG100 and TNG50, and compare the results with X-ray observations of nearby early-type galaxies. The simulations reproduce the observed X-ray luminosities (LX) and temperature (TX) at small (<Re) and intermediate (<5Re) radii reasonably well. We find that the X-ray properties of lower mass galaxies depend on their star formation rates. In particular, in the magnitude range where the star-forming and quenched populations overlap, we find that the X-ray luminosities of star-forming galaxies are on average about an order of magnitude higher than those of their quenched counterparts. We show that this diversity in LX is a direct manifestation of the quenching mechanism in the simulations, where the galaxies are quenched due to gas expulsion driven by SMBH kinetic feedback. The observed dichotomy in LX is thus an important observable prediction for the SMBH feedback-based quenching mechanisms implemented in state-of-the-art cosmological simulations. While the current X-ray observations of star-forming galaxies are broadly consistent with the predictions of the simulations, the observed samples are small and more decisive tests are expected from the sensitive all-sky X-ray survey with eROSITA.

published in
Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 1, pp.549-570, March 2020

links to paper
[ADS][arXiv]

Vogelsberger et al. (2020)

High-redshift JWST predictions from IllustrisTNG: dust modelling and galaxy luminosity functions

by
Vogelsberger, Mark; Nelson, Dylan; Pillepich, Annalisa; Shen, Xuejian; Marinacci, Federico; Springel, Volker; Pakmor, Rüdiger; Tacchella, Sandro; Weinberger, Rainer; Torrey, Paul; Hernquist, Lars

abstract
The James Webb Space Telescope (JWST) promises to revolutionize our understanding of the early Universe, and contrasting its upcoming observations with predictions of the Λ cold dark matter model requires detailed theoretical forecasts. Here, we exploit the large dynamic range of the IllustrisTNG simulation suite, TNG50, TNG100, and TNG300, to derive multiband galaxy luminosity functions from z = 2 to z = 10. We put particular emphasis on the exploration of different dust attenuation models to determine galaxy luminosity functions for the rest-frame ultraviolet (UV), and apparent wide NIRCam bands. Our most detailed dust model is based on continuum Monte Carlo radiative transfer calculations employing observationally calibrated dust properties. This calibration results in constraints on the redshift evolution of the dust attenuation normalization and dust-to-metal ratios yielding a stronger redshift evolution of the attenuation normalization compared to most previous theoretical studies. Overall we find good agreement between the rest-frame UV luminosity functions and observational data for all redshifts, also beyond the regimes used for the dust model calibrations. Furthermore, we also recover the observed high-redshift (z = 4-6) UV luminosity versus stellar mass relation, the H α versus star formation rate relation, and the H α luminosity function at z = 2. The bright end (MUV > -19.5) cumulative galaxy number densities are consistent with observational data. For the F200W NIRCam band, we predict that JWST will detect ∼80 (∼200) galaxies with a signal-to-noise ratio of 10 (5) within the NIRCam field of view, 2.2× 2.2 arcmin2, for a total exposure time of 10^5 s in the redshift range z = 8 ± 0.5. These numbers drop to ∼10 (∼40) for an exposure time of 10^4 s.

published in
Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 4, p.5167-5201, March 2020

links to paper
[ADS][arXiv]

Wang et al. (2020)

Early-type galaxy density profiles from IllustrisTNG – I. Galaxy correlations and the impact of baryons

by
Wang, Yunchong; Vogelsberger, Mark; Xu, Dandan; Mao, Shude; Springel, Volker; Li, Hui; Barnes, David; Hernquist, Lars; Pillepich, Annalisa; Marinacci, Federico; Pakmor, Rüediger; Weinberger, Rainer; Torrey, Paul

abstract
We explore the isothermal total density profiles of early-type galaxies (ETGs) in the IllustrisTNG simulation. For the selected 559 ETGs at z = 0 with stellar masses 10^{10.7} M_{☉ } ≤ M_{\ast } ≤ 10^{11.9} M_{☉ }, the total power-law slope has a mean of <γ′> = 2.011 ± 0.007 and a scatter of σ _{γ ^’ }} = 0.171 over the radial range 0.4-4 times the stellar half-mass radius. Several correlations between γ′ and galactic properties including stellar mass, effective radius, stellar surface density, central velocity dispersion, central dark matter fraction, and in situ-formed stellar mass ratio are compared to observations and other simulations, revealing that IllustrisTNG reproduces many correlation trends, and in particular, γ′ is almost constant with redshift below z = 2. Through analysing IllustrisTNG model variations, we show that black hole kinetic winds are crucial to lowering γ′ and matching observed galaxy correlations. The effects of stellar winds on γ′ are subdominant compared to active galactic nucleus (AGN) feedback, and differ due to the presence of AGN feedback from previous works. The density profiles of the ETG dark matter haloes are well described by steeper than NFW profiles, and they are steeper in the full physics (FP) run than their counterparts in the dark matter-only (DMO) run. Their inner density slopes anticorrelate (remain constant) with the halo mass in the FP (DMO) run, and anticorrelate with the halo concentration parameter c200 in both the types of runs. The dark matter haloes of low-mass ETGs are contracted whereas high-mass ETGs are expanded, suggesting that variations in the total density profile occur through the different halo responses to baryons.

published in
Monthly Notices of the Royal Astronomical Society, Volume 491, Issue 4, p.5188-5215, February 2020

links to paper
[ADS][arXiv]

Nelson et al. (2019)

First results from the TNG50 simulation: galactic outflows driven by supernovae and black hole feedback

by
Nelson, Dylan; Pillepich, Annalisa; Springel, Volker; Pakmor, Rüdiger; Weinberger, Rainer; Genel, Shy; Torrey, Paul; Vogelsberger, Mark; Marinacci, Federico; Hernquist, Lars

abstract
We present the new TNG50 cosmological, magnetohydrodynamical simulation – the third and final volume of the IllustrisTNG project. This simulation occupies a unique combination of large volume and high resolution, with a 50 Mpc box sampled by 21603 gas cells (baryon mass of 8 × 104 M). The median spatial resolution of star-forming interstellar medium gas is ∼100-140 pc. This resolution approaches or exceeds that of modern `zoom’ simulations of individual massive galaxies, while the volume contains ∼20 000 resolved galaxies with M_\star ≳ 10^7 M. Herein we show first results from TNG50, focusing on galactic outflows driven by supernovae as well as supermassive black hole feedback. We find that the outflow mass loading is a non-monotonic function of galaxy stellar mass, turning over and rising rapidly above 1010.5 M due to the action of the central black hole (BH). The outflow velocity increases with stellar mass, and at fixed mass it is faster at higher redshift. The TNG model can produce high-velocity, multiphase outflows that include cool, dense components. These outflows reach speeds in excess of 3000 km s-1 out to 20 kpc with an ejective, BH-driven origin. Critically, we show how the relative simplicity of model inputs (and scalings) at the injection scale produces complex behaviour at galactic and halo scales. For example, despite isotropic wind launching, outflows exhibit natural collimation and an emergent bipolarity. Furthermore, galaxies above the star-forming main sequence drive faster outflows, although this correlation inverts at high mass with the onset of quenching, whereby low-luminosity, slowly accreting, massive BHs drive the strongest outflows.

published in

Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 3, p.3234-3261, December 2019

links to paper
[ADS][arXiv]

Pillepich et al. (2019)

First results from the TNG50 simulation: the evolution of stellar and gaseous discs across cosmic time

by
Pillepich, Annalisa; Nelson, Dylan; Springel, Volker; Pakmor, Rüdiger; Torrey, Paul; Weinberger, Rainer; Vogelsberger, Mark; Marinacci, Federico; Genel, Shy; van der Wel, Arjen; Hernquist, Lars

abstract
We present a new cosmological, magnetohydrodynamical simulation for galaxy formation: TNG50, the third and final instalment of the IllustrisTNG project. TNG50 evolves 2 × 21603 dark matter particles and gas cells in a volume 50 comoving Mpc across. It hence reaches a numerical resolution typical of zoom-in simulations, with a baryonic element mass of 8.5× 10^4 M_{\odot } and an average cell size of 70-140 pc in the star-forming regions of galaxies. Simultaneously, TNG50 samples ∼700 (6500) galaxies with stellar masses above 10^{10} (10^8) M_{\odot } at z = 1. Here we investigate the structural and kinematical evolution of star-forming galaxies across cosmic time (0 ≲ z ≲ 6). We quantify their sizes, disc heights, 3D shapes, and degree of rotational versus dispersion-supported motions as traced by rest-frame V-band light (i.e. roughly stellar mass) and by H α light (i.e. star-forming and dense gas). The unprecedented resolution of TNG50 enables us to model galaxies with sub-kpc half-light radii and with ≲300-pc disc heights. Coupled with the large-volume statistics, we characterize a diverse, redshift- and mass-dependent structural and kinematical morphological mix of galaxies all the way to early epochs. Our model predicts that for star-forming galaxies the fraction of disc-like morphologies, based on 3D stellar shapes, increases with both cosmic time and galaxy stellar mass. Gas kinematics reveal that the vast majority of 10^{9-11.5} M_{\odot } star-forming galaxies are rotationally supported discs for most cosmic epochs (Vrot/σ > 2-3, z ≲ 5), being dynamically hotter at earlier epochs (z ≳ 1.5). Despite large velocity dispersion at high redshift, cold and dense gas in galaxies predominantly arranges in disky or elongated shapes at all times and masses; these gaseous components exhibit rotationally dominated motions far exceeding the collisionless stellar bodies.

published in
Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 3, p.3196-3233, December 2019

links to paper
[ADS][arXiv]

Xu et al. (2019)

A study of stellar orbit fractions: simulated IllustrisTNG galaxies compared to CALIFA observations

by
Xu, Dandan; Zhu, Ling; Grand, Robert; Springel, Volker; Mao, Shude; van de Ven, Glenn; Lu, Shengdong; Wang, Yougang; Pillepich, Annalisa; Genel, Shy; Nelson, Dylan; Rodriguez-Gomez, Vicente; Pakmor, Rüdiger; Weinberger, Rainer; Marinacci, Federico; Vogelsberger, Mark; Torrey, Paul; Naiman, Jill; Hernquist, Lars

abstract
Motivated by the recently discovered kinematic `Hubble sequence’ shown by the stellar orbit-circularity distribution of 260 CALIFA galaxies, we make use of a comparable galaxy sample at z = 0 with a stellar mass range of M_{*}/M_{\odot }\in [10^{9.7}, 10^{11.4}] selected from the IllustrisTNG simulation and study their stellar orbit compositions in relation to a number of other fundamental galaxy properties. We find that the TNG100 simulation broadly reproduces the observed fractions of different orbital components and their stellar mass dependences. In particular, the mean mass dependences of the luminosity fractions for the kinematically warm and hot orbits are well reproduced within model uncertainties of the observed galaxies. The simulation also largely reproduces the observed peak and trough features at M_{*}≈ 1{-}2× 10^{10} M_{\odot } in the mean distributions of the cold- and hot-orbit fractions, respectively, indicating fewer cooler orbits and more hotter orbits in both more- and less-massive galaxies beyond such a mass range. Several marginal disagreements are seen between the simulation and observations: the average cold-orbit (counter-rotating) fractions of the simulated galaxies below (above) M_{*}≈ 6× 10^{10} M_{\odot } are systematically higher than the observational data by ≲ 10{{ per cent}} (absolute orbital fraction); the simulation also seems to produce more scatter for the cold-orbit fraction and less so for the non-cold orbits at any given galaxy mass. Possible causes that stem from the adopted heating mechanisms are discussed.

published in
Monthly Notices of the Royal Astronomical Society, Volume 489, Issue 1, p.842-854, October 2019

links
[ADS][arXiv]

Donnari et al. (2019)

The star formation activity of IllustrisTNG galaxies: main sequence, UVJ diagram, quenched fractions, and systematics

by
Donnari, Martina; Pillepich, Annalisa; Nelson, Dylan; Vogelsberger, Mark; Genel, Shy; Weinberger, Rainer; Marinacci, Federico; Springel, Volker; Hernquist, Lars

abstract
We select galaxies from the IllustrisTNG hydrodynamical simulations (M_stars> 10^9 M_☉ at 0 ≤ z ≤ 2) and characterize the shapes and evolutions of their UVJ and star formation rate-stellar mass (SFR-Mstars) diagrams. We quantify the systematic uncertainties related to different criteria to classify star-forming versus quiescent galaxies, different SFR estimates, and by accounting for the star formation measured within different physical apertures. The TNG model returns the observed features of the UVJ diagram at z ≤ 2, with a clear separation between two classes of galaxies. It also returns a tight star-forming main sequence (MS) for M_stars< 10^{10.5} (M_☉) with a ̃0.3 dex scatter at z ̃ 0 in our fiducial choices. If a UVJ-based cut is adopted, the TNG MS exhibits a downwardly bending at stellar masses of about 1010.5-10.7 M. Moreover, the model predicts that {̃ }80 (50) per cent of 1010.5-11 Mgalaxies at z = 0 (z = 2) are quiescent and the numbers of quenched galaxies at intermediate redshifts and high masses are in better agreement with observational estimates than previous models. However, shorter SFR-averaging time-scales imply higher normalizations and scatter of the MS, while smaller apertures lead to underestimating the galaxy SFRs: overall we estimate the inspected systematic uncertainties to sum up to about 0.2-0.3 dex in the locus of the MS and to about 15 percentage points in the fraction of quenched galaxies. While TNG colour distributions are clearly bimodal, this is not the case for the SFR logarithmic distributions in bins of stellar mass (SFR ≳ 10-3Myr-1). Finally, the slope and z = 0 normalization of the TNG MS are consistent with observational findings; however, the locus of the TNG MS remains lower by about 0.2-0.5 dex at 0.75 ≤ z < 2 than the available observational estimates taken at face value.

published in
Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 4, p.4817-4840, June 2019

links to paper
[ADS][arXiv]

Martizzi et al. (2019)

Baryons in the Cosmic Web of IllustrisTNG – I: gas in knots, filaments, sheets, and voids

by
Martizzi, Davide; Vogelsberger, Mark; Artale, Maria Celeste; Haider, Markus; Torrey, Paul; Marinacci, Federico; Nelson, Dylan; Pillepich, Annalisa; Weinberger, Rainer; Hernquist, Lars; Naiman, Jill; Springel, Volker

abstract
We analyse the IllustrisTNG simulations to study the mass, volume fraction, and phase distribution of gaseous baryons embedded in the knots, filaments, sheets, and voids of the Cosmic Web from redshift z = 8 to redshift z = 0. We find that filaments host more star-forming gas than knots, and that filaments also have a higher relative mass fraction of gas in this phase than knots. We also show that the cool, diffuse intergalactic medium [IGM; T< 10^5 K, n_H< 10^{-4}(1+z) cm^{-3}] and the warm-hot intergalactic medium [WHIM; 10^5 < T< 10^7 K, n_H < 10^{-4}(1+z) cm^{-3}] constitute {̃ } 39 and {̃ } 46{{ per cent}} of the baryons at redshift z = 0, respectively. Our results indicate that the WHIM may constitute the largest reservoir of missing baryons at redshift z = 0. Using our Cosmic Web classification, we predict the WHIM to be the dominant baryon mass contribution in filaments and knots at redshift z = 0, but not in sheets and voids where the cool, diffuse IGM dominates. We also characterize the evolution of WHIM and IGM from redshift z = 4 to redshift z = 0, and find that the mass fraction of WHIM in filaments and knots evolves only by a factor of ̃2 from redshift z = 0 to 1, but declines faster at higher redshift. The WHIM only occupies 4-11 per cent of the volume at redshift 0 ≤ z ≤ 1. We predict the existence of a significant number of currently undetected O VII and Ne IX absorption systems in cosmic filaments, which could be detected by future X-ray telescopes like Athena.

published in
Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 3, p.3766-3787, July 2019

links to paper
[ADS][arXiv]

Nelson et al. (2019)

The IllustrisTNG simulations: public data release

by
Nelson, Dylan; Springel, Volker; Pillepich, Annalisa; Rodriguez-Gomez, Vicente; Torrey, Paul; Genel, Shy; Vogelsberger, Mark; Pakmor, Ruediger; Marinacci, Federico; Weinberger, Rainer; Kelley, Luke; Lovell, Mark; Diemer, Benedikt; Hernquist, Lars

abstract
We present the full public release of all data from the TNG100 and TNG300 simulations of the IllustrisTNG project. IllustrisTNG is a suite of large volume, cosmological, gravo-magnetohydrodynamical simulations run with the moving-mesh code Arepo. TNG includes a comprehensive model for galaxy formation physics, and each TNG simulation self-consistently solves for the coupled evolution of dark matter, cosmic gas, luminous stars, and supermassive black holes from early time to the present day, z=0. Each of the flagship runs—TNG50, TNG100, and TNG300—are accompanied by halo/subhalo catalogs, merger trees, lower-resolution and dark-matter only counterparts, all available with 100 snapshots. We discuss scientific and numerical cautions and caveats relevant when using TNG. The data volume now directly accessible online is ̃750 TB, including 1200 full volume snapshots and ̃80,000 high time-resolution subbox snapshots. This will increase to ̃1.1 PB with the future release of TNG50. Data access and analysis examples are available in IDL, Python, and Matlab. We describe improvements and new functionality in the web-based API, including on-demand visualization and analysis of galaxies and halos, exploratory plotting of scaling relations and other relationships between galactic and halo properties, and a new JupyterLab interface. This provides an online, browser-based, near-native data analysis platform enabling user computation with local access to TNG data, alleviating the need to download large datasets.

published in
Computational Astrophysics and Cosmology, Volume 6, Issue 1, article id. 2, 29 pp., May 2019

links to paper
[ADS][arXiv]

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