An official website of the United States government
Abstract We present radial profiles of luminosity-weighted age (ageL) and ΔΣSFRfor various populations of high- and low-mass central and satellite galaxies in the TNG100 cosmological simulation. Using these profiles, we investigate the impact of intrinsic and environmental factors on the radial distribution of star formation. For both central galaxies and satellites, we investigate the effects of black hole mass, cumulative active galactic nucleus (AGN) feedback energy, morphology, halo mass, and local galaxy overdensity on the profiles. In addition, we investigate the dependence of radial profiles of the satellite galaxies as a function of the redshifts at which they joined their hosts, as well as the net change in star-forming gas mass since the satellites joined their host. We find that high-mass (M*> 1010.5M⊙) central and satellite galaxies show evidence of inside-out quenching driven by AGN feedback. Effects from environmental processes only become apparent in averaged profiles at extreme halo masses and local overdensities. We find that the dominant quenching process for low-mass galaxies (M*< 1010M⊙) is environmental, generally occurring at low halo mass and high local galaxy overdensity for low-mass central galaxies and at high host halo masses for low-mass satellite galaxies. Overall, we find that environmental processes generally drive quenching from the outside-in.
more »
« less
Black Hole Growth, Baryon Lifting, Star Formation, and IllustrisTNG
Abstract Quenching of star formation in the central galaxies of cosmological halos is thought to result from energy released as gas accretes onto a supermassive black hole. The same energy source also appears to lower the central density and raise the cooling time of baryonic atmospheres in massive halos, thereby limiting both star formation and black hole growth, by lifting the baryons in those halos to greater altitudes. One predicted signature of that feedback mechanism is a nearly linear relationship between the central black hole’s mass (MBH) and the original binding energy of the halo’s baryons. We present the increasingly strong observational evidence supporting a such a relationship, showing that it extends up to halos of massMhalo∼ 1014M⊙. We then compare current observational constraints on theMBH–Mhalorelation with numerical simulations, finding that black hole masses in IllustrisTNG appear to exceed those constraints atMhalo< 1013M⊙and that black hole masses in EAGLE fall short of observations atMhalo∼ 1014M⊙. A closer look at IllustrisTNG shows that quenching of star formation and suppression of black hole growth do indeed coincide with black hole energy input that lifts the halo’s baryons. However, IllustrisTNG does not reproduce the observedMBH–Mhalorelation because its black holes gain mass primarily through accretion that does not contribute to baryon lifting. We suggest adjustments to some of the parameters in the IllustrisTNG feedback algorithm that may allow the resulting black hole masses to reflect the inherent links between black hole growth, baryon lifting, and star formation among the massive galaxies in those simulations.
more »
« less
- Award ID(s):
- 2106575
- PAR ID:
- 10536101
- Publisher / Repository:
- IOP
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 960
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 28
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The circumgalactic medium (CGM) is a reservoir of metals and star-forming fuel. Most baryons in the Universe are in the CGM or the intergalactic medium (IGM). The baryon cycle—how mass and metals reach the CGM from the inner regions of the galaxy and how gas from the CGM replenishes star-forming activity in the inner regions—is an essential question in galaxy evolution. In this paper, we study the flow of mass and metals in a stacked sample of 2770 isolated halos from the IllustrisTNG100 cosmological hydrodynamic simulation. The mean gas flow as a function of radius and angle is similar across a large galactic mass range when accounting for different feedback modes. Although both star formation and black holes cause powerful outflows, the flows from star formation are more angularly restricted. Black hole feedback dominates mass flow throughout the halo, while star formation feedback mainly affects the inner region. When scaling by virial radius (Rv), large dynamical changes occur at 0.2Rvfor most halos, suggesting a characteristic size for the inner galaxy. Despite kinetic-mode feedback from black holes being the primary quenching mechanism in IllustrisTNG, a small population of high-mass kinetic-mode disks are able to form stars.more » « less
-
Abstract We present measurements of black hole masses and Eddington ratios (λEdd) for a sample of 38 bright (M1450< −24.4 mag) quasars at 5.8 ≲z≲ 7.5, derived from Very Large Telescope/X–shooter near–IR spectroscopy of their broad Civand Mgiiemission lines. The black hole masses (on average,MBH∼ 4.6 × 109M⊙) and accretion rates (0.1 ≲λEdd≲ 1.0) are broadly consistent with that of similarly luminous 0.3 ≲z≲ 2.3 quasars, but there is evidence for a mild increase in the Eddington ratio abovez≳ 6. Combined with deep Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 158μm line from the host galaxies and VLT/MUSE investigations of the extended Lyαhalos, this study provides fundamental clues to models of the formation and growth of the first massive galaxies and black holes. Compared to local scaling relations,z≳ 5.7 black holes appear to be over-massive relative to their hosts, with accretion properties that do not change with host galaxy morphologies. Assuming that the kinematics of theT∼ 104K gas, traced by the extended Lyαhalos, are dominated by the gravitational potential of the dark matter halo, we observe a similar relation between black hole mass and circular velocity as reported forz∼ 0 galaxies. These results paint a picture where the first supermassive black holes reside in massive halos atz≳ 6 and lead the first stages of galaxy formation by rapidly growing in mass with a duty cycle of order unity. The duty cycle needs to drastically drop toward lower redshifts, while the host galaxies continue forming stars at a rate of hundreds of solar masses per year, sustained by the large reservoirs of cool gas surrounding them.more » « less
-
Abstract We investigate the impact of massive primordial black holes (PBHs;mBH ∼ 106M⊙) on the star formation and first galaxy assembly process using high-resolution hydrodynamical simulations fromz= 1100 toz ∼ 9. We find that PBH accretion is self-regulated by feedback, suppressing mass growth unless feedback is weak. PBHs accelerate structure formation by seeding dark matter (DM) halos and gravitationally attracting gas, but strong feedback can delay cooling and suppress star formation. In addition, the presence of baryon-DM streaming creates an offset between the PBH location and the peaks induced in gas density, promoting earlier and more efficient star formation compared to standard ΛCDM. Byz ∼ 10, PBH-seeded galaxies form dense star clusters, with PBH-to-stellar mass ratios comparable to observed high-zactive galactic nuclei like UHZ-1. Our results support PBHs as viable supermassive black hole (SMBH) seeds but do not exclude alternative scenarios. We emphasize that PBH-seeding provides a natural explanation for some of the newly discovered overmassive SMBHs at high redshift, in particular those with extreme ratios of BH-to-dynamical (virial) mass that challenge standard formation channels. Future studies with ultra-deep JWST surveys, the Roman Space Telescope, and radio surveys with facilities such as the Square Kilometre Array and Hydrogen Epoch of Reionization Array will be critical in distinguishing PBH-driven SMBH growth from other pathways.more » « less
-
Abstract Most galaxies, including the Milky Way, host a supermassive black hole (SMBH) at the center. These SMBHs can be observed out to high redshifts (z≥ 6) if the accretion rate is sufficiently large. However, we do not fully understand the mechanism through which these black holes form at early times. The heavy (or direct collapse) seeding mechanism has emerged as a probable contender in which the core of an atomic cooling halo directly collapses into a dense stellar cluster that could host supermassive stars that proceed to form a black hole seed of mass ∼ 105M⊙. We use the Renaissance Simulations to investigate the properties of 35 direct collapse black hole (DCBH) candidate host halos atz = 15–24 and compare them to noncandidate halos. We aim to understand what features differentiate halos capable of hosting a DCBH from the general halo population with the use of statistical analysis and machine learning methods. We examine 18 halo, central, and environmental properties. We find that DCBH candidacy is more dependent on a halo’s core internal properties than on exterior factors such as Lyman–Werner (LW) flux and distance to the closest galaxy; our analysis selects density and radial mass influx as the most important features (outside candidacy establishing features). Our results concur with the recent suggestion that DCBH host halos neither need to lie within a “Goldilocks zone” nor have a significant amount of LW flux to suppress cooling. This paper presents insight to the dynamics possibly occurring in potential DCBH host halos and seeks to provide guidance to DCBH subgrid formation models.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3847/1538-4357/ad0039
