scholarly journals Characterizing mass, momentum, energy and metal outflow rates of multi-phase galactic winds in the FIRE-2 cosmological simulations

2021 ◽  
Author(s):  
Viraj Pandya ◽  
Drummond B Fielding ◽  
Daniel Anglés-Alcázar ◽  
Rachel S Somerville ◽  
Greg L Bryan ◽  
...  
Keyword(s):  
Milky Way ◽  
High Redshift ◽  
Mass Loading ◽  
Intermediate Mass ◽  
Order Unity ◽  
Massive Galaxies ◽  
Galactic Winds ◽  
Low Mass ◽  
Halo Gas ◽  
Multi Phase

Abstract We characterize mass, momentum, energy and metal outflow rates of multi-phase galactic winds in a suite of FIRE-2 cosmological ‘zoom-in’ simulations from the Feedback in Realistic Environments (FIRE) project. We analyse simulations of low-mass dwarfs, intermediate-mass dwarfs, Milky Way-mass haloes, and high-redshift massive haloes. Consistent with previous work, we find that dwarfs eject about 100 times more gas from their interstellar medium (ISM) than they form in stars, while this mass ‘loading factor’ drops below one in massive galaxies. Most of the mass is carried by the hot phase (>105 K) in massive haloes and the warm phase (103 − 105 K) in dwarfs; cold outflows (<103 K) are negligible except in high-redshift dwarfs. Energy, momentum and metal loading factors from the ISM are of order unity in dwarfs and significantly lower in more massive haloes. Hot outflows have 2 − 5 × higher specific energy than needed to escape from the gravitational potential of dwarf haloes; indeed, in dwarfs, the mass, momentum, and metal outflow rates increase with radius whereas energy is roughly conserved, indicating swept up halo gas. Burst-averaged mass loading factors tend to be larger during more powerful star formation episodes and when the inner halo is not virialized, but we see effectively no trend with the dense ISM gas fraction. We discuss how our results can guide future controlled numerical experiments that aim to elucidate the key parameters governing galactic winds and the resulting associated preventative feedback.

scholarly journals A new channel to form IMBHs throughout cosmic time

2020 ◽  
Vol 501 (1) ◽  
pp. 1413-1425
Author(s):  
Priyamvada Natarajan
Keyword(s):  
High Redshift ◽  
Cosmic Time ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Net Zero ◽  
Wide Range ◽  
Low Mass ◽  
Gas Accretion ◽  
Growth Scaling ◽  
Gas Supply

ABSTRACT While the formation of the first black holes (BHs) at high redshift is reasonably well understood though debated, massive BH formation at later cosmic epochs has not been adequately explored. We present a gas accretion driven mechanism that can build-up BH masses rapidly in dense, gas-rich nuclear star clusters (NSCs). Wind-fed supraexponential accretion in these environments under the assumption of net zero angular momentum for the gas, can lead to extremely rapid growth, scaling stellar mass remnant seed BHs up to the intermediate mass black hole (IMBH) range. This new long-lived channel for IMBH formation permits growth to final masses ranging from 50 to 105 M⊙. Growth is modulated by the gas supply, and premature termination can result in the formation of BHs with masses between 50 and a few 100 M⊙ filling in the so-called mass gap. Typically, growth is unimpeded and will result in the formation of IMBHs with masses ranging from ∼100 to 105 M⊙. New detections from the LIGO–VIRGO source GW190521 to the emerging population of ∼105 M⊙ BHs harboured in low-mass dwarf galaxies are revealing this elusive population. Naturally accounting for the presence of off-centre BHs in low-mass dwarfs, this new pathway also predicts the existence of a population of wandering non-central BHs in more massive galaxies detectable via tidal disruption events and as gravitational wave coalescences. Gas-rich NSCs could therefore serve as incubators for the continual formation of BHs over a wide range in mass throughout cosmic time.

scholarly journals Chemodynamical evolution of galaxies with hypernovae

2007 ◽  
Vol 3 (S245) ◽  
pp. 23-26
Author(s):  
Chiaki Kobayashi
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Formation Rate ◽  
Large Contribution ◽  
Milky Way Galaxy ◽  
Massive Galaxies ◽  
Evolution Of Galaxies ◽  
Low Mass ◽  
Formation And Evolution ◽  
The Difference

AbstractWe simulate the formation and evolution of galaxies with a hydrodynamical model including supernova and hypernova feedback. The large contribution of hypernovae is required from the observed abundance ratios in the Milky Way Galaxy. The hypernova feedback suppress star formation efficiently, which results in the cosmic star formation rate history peaked at z ~ 4. It also drives galactic outflows efficiently in low mass galaxies, and these winds eject heavy elements into the intergalactic medium. The ejected baryon and metal fraction is larger for less massive galaxies, which results in the mass-metallicity relation of galaxies. We also simulate the chemodynamical evolution of the Milky Way Galaxy, and show the difference of the stellar populations in the bulge and disk.

Fossil SMBHs in the Milky Way Halo

2009 ◽  
Vol 5 (S267) ◽  
pp. 196-196
Author(s):  
Jillian Bellovary ◽  
Fabio Governato ◽  
Tom Quinn
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Star Formation ◽  
Milky Way ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Hierarchical Assembly ◽  
Supernova Feedback ◽  
Black Hole Candidates ◽  
Milky Way Halo

As galaxies assemble through hierarchical merging, some black holes grow to become the central black holes of massive galaxies; however, others may be stripped via interactions into regions of galaxies where they will remain quiescent. Such objects may be the source of observed off-nuclear intermediate-mass black hole candidates, as detected by Farrell et al. (2009). We use a cosmological N-body simulation of a disk-dominated galaxy (Vc = 140 km s−1, presented by Governato et al. 2009) to examine the formation and merging histories of seed black holes during hierarchical assembly. Our method incorporates star formation, supernova feedback, a physically motivated description of black hole seed creation, growth, and merging.

scholarly journals Evolution of C iv Absorbers. II. Where Does C iv Live?

2022 ◽  
Vol 924 (1) ◽  
pp. 12
Author(s):  
Farhanul Hasan ◽  
Christopher W. Churchill ◽  
Bryson Stemock ◽  
Nikole M. Nielsen ◽  
Glenn G. Kacprzak ◽  
...  
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Dark Matter Halos ◽  
Lower Mass ◽  
Massive Galaxies ◽  
Galaxy Halos ◽  
Low Mass ◽  
Galaxy Halo ◽  
Halo Gas

Abstract We use the observed cumulative statistics of C iv absorbers and dark matter halos to infer the distribution of C iv-absorbing gas relative to galaxies at redshifts 0 ≤ z ≤ 5. We compare the cosmic incidence dN/dX of C iv absorber populations and galaxy halos, finding that massive L ≥ L ⋆ halos alone cannot account for all the observed W r ≥ 0.05 Å absorbers. However, the dN/dX of lower-mass halos exceeds that of W r ≥ 0.05 Å absorbers. We also estimate the characteristic gas radius of absorbing structures required for the observed C iv dN/dX, assuming each absorber is associated with a single galaxy halo. The W r ≥ 0.3 Å and W r ≥ 0.6 Å C iv gas radii are ∼30%–70% (∼20%–40%) of the virial radius of L ⋆ (0.1L ⋆) galaxies, and the W r ≥ 0.05 Å gas radius is ∼100%–150% (∼60%–100%) of the virial radius of L ⋆ (0.1L ⋆) galaxies. For stronger absorbers, the gas radius relative to the virial radius rises across Cosmic Noon and falls afterwards, while for weaker absorbers, the relative gas radius declines across Cosmic Noon and then dramatically rises at z < 1. A strong luminosity-dependence of the gas radius implies highly extended C iv envelopes around massive galaxies before Cosmic Noon, while a luminosity-independent gas radius implies highly extended envelopes around dwarf galaxies after Cosmic Noon. From available absorber-galaxy and C iv evolution data, we favor a scenario in which low-mass galaxies enrich the volume around massive galaxies at early epochs and propose that the outer halo gas (>0.5 R v ) was produced primarily in ancient satellite dwarf galaxy outflows, while the inner halo gas (<0.5 R v ) originated from the central galaxy and persists as recycled accreting gas.

scholarly journals Galactic outflow rates in the EAGLE simulations

2020 ◽  
Vol 494 (3) ◽  
pp. 3971-3997 ◽  
Author(s):  
Peter D Mitchell ◽  
Joop Schaye ◽  
Richard G Bower ◽  
Robert A Crain
Keyword(s):  
Galactic Nuclei ◽  
Mass Function ◽  
Mass Loading ◽  
Stellar Feedback ◽  
Galactic Winds ◽  
Wide Range ◽  
The Galaxy ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
Halo Masses

ABSTRACT We present measurements of galactic outflow rates from the eagle suite of cosmological simulations. We find that gas is removed from the interstellar medium (ISM) of central galaxies with a dimensionless mass loading factor that scales approximately with circular velocity as $V_{\mathrm{c}}^{-3/2}$ in the low-mass regime where stellar feedback dominates. Feedback from active galactic nuclei causes an upturn in the mass loading for halo masses ${\gt}10^{12} \, \mathrm{M_\odot }$. We find that more gas outflows through the halo virial radius than is removed from the ISM of galaxies, particularly at low redshifts, implying substantial mass loading within the circumgalactic medium. Outflow velocities span a wide range at a given halo mass/redshift, and on average increase positively with redshift and halo mass up to $M_{200} \sim 10^{12} \, \mathrm{M_\odot }$. Outflows exhibit a bimodal flow pattern on circumgalactic scales, aligned with the galactic minor axis. We present a number of like-for-like comparisons to outflow rates from other recent cosmological hydrodynamical simulations, and show that comparing the propagation of galactic winds as a function of radius reveals substantial discrepancies between different models. Relative to some other simulations, eagle favours a scenario for stellar feedback where agreement with the galaxy stellar mass function is achieved by removing smaller amounts of gas from the ISM, but with galactic winds that then propagate and entrain ambient gas out to larger radii.

scholarly journals The systematically varying stellar IMF

2019 ◽  
Vol 14 (S351) ◽  
pp. 117-121 ◽  
Author(s):  
Pavel Kroupa
Keyword(s):  
Globular Clusters ◽  
Massive Star ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Star Formation Rate ◽  
High Redshift ◽  
Formation Rate ◽  
Low Mass Stars ◽  
Dynamical Mass ◽  
Low Mass

AbstractSome ultra-compact dwarf galaxies have large dynamical mass to light (M / L) ratios and also appear to contain an overabundance of LMXB sources, and some Milky Way globular clusters have a low concentration and appear to have a deficit of low-mass stars. These observations can be explained if the stellar IMF becomes increasingly top-heavy with decreasing metallicity and increasing gas density of the forming object. The thus constrained stellar IMF then accounts for the observed trend of metallicity and M / L ratio found amongst M31 globular star clusters. It also accounts for the overall shift of the observationally deduced galaxy-wide IMF from top-light to top-heavy with increasing star formation rate amongst galaxies. If the IMF varies similarly to deduced here, then extremely young very massive star-burst clusters observed at a high redshift would appear quasar-like (Jerabkova et al. 2017).

scholarly journals What dominates the X-ray emission of normal galaxies?

2015 ◽  
Vol 11 (A29B) ◽  
pp. 124-135
Author(s):  
Ann E. Hornschemeier ◽  
Anna Wolter ◽  
Dong-Woo Kim
Keyword(s):  
Black Holes ◽  
High Redshift ◽  
Cosmic Time ◽  
Compact Objects ◽  
Intermediate Mass ◽  
X Ray ◽  
Massive Galaxies ◽  
Normal Galaxies ◽  
Ring Galaxies ◽  
Intermediate Mass Black Holes

AbstractX-ray surveys of normal galaxies, i.e. those that do not host actively supermassive black holes, have revealed important information on the nature of accreting stellar-mass compact objects (neutron stars and black holes), constraints on populations of possible intermediate-mass black holes (102–5M⊙), and on the reservoir of materials in the hot interstellar medium of the most massive galaxies. Here we summarize briefly the results of Chandra and NuSTAR surveys of several samples of galaxies covered during the 2015 IAU General Assembly. This includes a comprehensive study of six nearby starburst galaxies by the NuSTAR mission, of high-redshift galaxies from the 6 Ms Chandra Deep Field South for which evolutionary trends in X-ray emission over cosmic time have been measured, of collisional ring galaxies which are excellent local environments for studying intermediate-mass black holes and of elliptical galaxies which are ideal for study of the hot gas reservoirs containing the effects of stellar and AGN feedback.

scholarly journals Simulations of Cosmic Chemical Enrichment

2006 ◽  
Vol 2 (S235) ◽  
pp. 271-272
Author(s):  
Chiaki Kobayashi
Keyword(s):  
Intergalactic Medium ◽  
Hydrodynamical Model ◽  
Heavy Elements ◽  
Massive Galaxies ◽  
Chemical Enrichment ◽  
Galactic Winds ◽  
Galactic Outflows ◽  
Low Mass ◽  
Mass Dependent

AbstractWe simulate cosmic chemical enrichment with a hydrodynamical model including supernova and hypernova feedback. We find that the majority of stars in present-day massive galaxies formed in much smaller galaxies at high redshifts, despite their late assembly times. The hypernova feedback drives galactic outflows efficiently in low mass galaxies, and these winds eject heavy elements into the intergalactic medium. The ejected baryon fraction is larger for less massive galaxies, correlates well with stellar metallicity. The observed mass-metallicity relation is well reproduced as a result of the mass-dependent galactic winds.

scholarly journals The origin of thick discs

2012 ◽  
Vol 10 (H16) ◽  
pp. 342-342
Author(s):  
Sébastien Comerón
Keyword(s):  
Time Scale ◽  
Milky Way ◽  
High Redshift ◽  
Large Mass ◽  
Short Time Scale ◽  
Giant Molecular Clouds ◽  
Secular Evolution ◽  
Thick Disc ◽  
Thin Disc ◽  
Low Mass

AbstractThick discs are defined to be disc-like components with a scale height larger than that of the classical discs. They are ubiquitous (Yoachim & Dalcanton 2006; Comerón et al. 2011a), they are made of mostly old and metal-poor stars and are most easily detected in close to edge-on galaxies. Their origin has been considered mysterious and several formation theories have been proposed:• The thick disc being formed secularly by thin disc stars heated by disc overdensities such as giant molecular clouds or spiral arms (Villumsen 1985, ApJ, 290, 75) and by stars moved outwards from their original orbits by radial migration mechanisms (Schönrich & Binney 2009).• The thick disc being formed by the heating of the thin disc by satellites (Quinn et al. 1993) and the tidal stripping of them (Abadi et al. 2003).• The thick disc being formed fast and already thick at high redshift in an highly unstable disc. Inside that thick disc, a thin disc would form afterwards as suggested by Elemgreen & Elmegreen (2006).• The thick disc being formed originally thick at high redshift by the merger of gas-rich protogalactic fragments and a thin disc forming afterwards within it (Brook et al. 2007).The first mechanism is a secular evolution mechanism. The time-scale of the second one is dependent on the merger history of the main galaxy. In the two last mechanisms, the thick disc forms already thick in a short time-scale at high redshift.Recent Milky Way studies, (see, e.g., Bovy et al. 2012), have shown indications that there is no discontinuity between the thin and the thick disc chemical and kinematic properties. Instead, those studies indicate the presence of a monotonic distribution of disc thicknesses. This would suggest a secular origin for the Milky Way thick disc.Studies in external galaxies (Yoachim & Dalcanton 2006; Comerón et al. 2011b), have shown that low-mass disc galaxies have thick disc relative masses much larger than those found in large-mass galaxies. Because low-mass galaxies are dynamically younger than their larger counterparts, it seems difficult for their thick discs to have a secular evolution origin, but simulations show that their thick disc masses are compatible with those of a thick disc formed at high redshift.Thus, recent studies seem to indicate that large-mass galaxies have their thick discs formed mainly due to secular evolution and that low-mass galaxies have them formed at high redshift.

Cold gas studies of a z = 2.5 protocluster

2020 ◽  
Vol 15 (S359) ◽  
pp. 136-140
Author(s):  
Minju M. Lee ◽  
Ichi Tanaka ◽  
Rohei Kawabe
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Kinematic Model ◽  
Molecular Gas ◽  
General View ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Kinematics ◽  
Narrow Band Filter ◽  
Stellar Masses

AbstractWe present studies of a protocluster at z =2.5, an overdense region found close to a radio galaxy, 4C 23.56, using ALMA. We observed 1.1 mm continuum, two CO lines (CO (4–3) and CO (3–2)) and the lower atomic carbon line transition ([CI](3P1-3P0)) at a few kpc (0″.3-0″.9) resolution. The primary targets are 25 star-forming galaxies selected as Hα emitters (HAEs) that are identified with a narrow band filter. These are massive galaxies with stellar masses of > 1010Mʘ that are mostly on the galaxy main sequence at z =2.5. We measure the molecular gas mass from the independent gas tracers of 1.1 mm, CO (3–2) and [CI], and investigate the gas kinematics of galaxies from CO (4–3). Molecular gas masses from the different measurements are consistent with each other for detection, with a gas fraction (fgas = Mgas/(Mgas+ Mstar)) of ≃ 0.5 on average but with a caveat. On the other hand, the CO line widths of the protocluster galaxies are typically broader by ˜50% compared to field galaxies, which can be attributed to more frequent, unresolved gas-rich mergers and/or smaller sizes than field galaxies, supported by our high-resolution images and a kinematic model fit of one of the galaxies. We discuss the expected scenario of galaxy evolution in protoclusters at high redshift but future large surveys are needed to get a more general view.

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