scholarly journals Galactic chimney sweeping: the effect of ‘gradual’ stellar feedback mechanisms on the evolution of dwarf galaxies

2019 ◽  
Vol 489 (3) ◽  
pp. 4278-4299
Author(s):  
Lilian Garratt-Smithson ◽  
Graham A Wynn ◽  
Chris Power ◽  
C J Nixon
Keyword(s):  
High Redshift ◽  
High Mass ◽  
Stellar Winds ◽  
Feedback Mechanisms ◽  
Dwarf Spheroidal Galaxies ◽  
Stellar Feedback ◽  
Hydrodynamical Simulations ◽  
Halo Masses ◽  
The Impact ◽  
Spheroidal Galaxies

ABSTRACT We investigate the impact of time-resolved ‘gradual’ stellar feedback processes in high redshift dwarf spheroidal galaxies. Here ‘gradual’ feedback refers to individual stellar feedback events which deposit energy over a period of time. We conduct high-resolution hydrodynamical simulations of dwarf spheroidal galaxies with halo masses of 107–108 M⊙, based on z = 6 progenitors of the Milky Way’s dwarf spheroidal galaxies. We also include a novel feedback prescription for individual massive stars, which includes stellar winds and an HMXB (high mass X-ray binary) phase, on top of supernovae. We find the mass of gas unbound across a 1 Gyr starburst is uniformly lowered if gradual feedback mechanisms are included across the range of metallicities, halo concentration parameters, and galaxy masses studied here. Furthermore, we find including gradual feedback in the smallest galaxies delays the unbinding of the majority of the gas and facilitates the production of ‘chimneys’ in the dense shell surrounding the feedback generated hot, pressurized ‘superbubble’. These ‘chimneys’ vent hot gas from the galaxy interior, lowering the temperature of the central 10 kpc of the gaseous halo. Additionally, we find radiative cooling has little effect on the energetics of simulations that include a short, violent starburst compared with those that have a longer, less concentrated starburst. Finally, we investigate the relative impact of HMXB feedback and stellar winds on our results, finding the ubiquity of stellar winds throughout each starburst makes them a defining factor in the final state of the interstellar medium.

scholarly journals The impact of AGN wind feedback in simulations of isolated galaxies with a multiphase ISM

2020 ◽  
Vol 497 (4) ◽  
pp. 5292-5308 ◽  
Author(s):  
Paul Torrey ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
Daniel Anglés-Alcázar ◽  
Eliot Quataert ◽  
...  
Keyword(s):  
Black Holes ◽  
High Redshift ◽  
Formation Rate ◽  
Feedback Mechanism ◽  
Host Galaxy ◽  
Merging Galaxies ◽  
Massive Black Holes ◽  
Stellar Feedback ◽  
Isolated Galaxies ◽  
The Impact

ABSTRACT Accreting black holes can drive fast and energetic nuclear winds that may be an important feedback mechanism associated with active galactic nuclei (AGN). In this paper, we implement a scheme for capturing feedback from these fast nuclear winds and examine their impact in simulations of isolated disc galaxies. Stellar feedback is modelled using the Feedback In Realistic Environments (fire) physics and produces a realistic multiphase interstellar medium (ISM). We find that AGN winds drive the formation of a low-density, high-temperature central gas cavity that is broadly consistent with analytic model expectations. The effects of AGN feedback on the host galaxy are a strong function of the wind kinetic power and momentum. Low- and moderate-luminosity AGN do not have a significant effect on their host galaxy: the AGN winds inefficiently couple to the ambient ISM and instead a significant fraction of their energy vents in the polar direction. For such massive black holes, accretion near the Eddington limit can have a dramatic impact on the host galaxy ISM: if AGN wind feedback acts for ≳20–30 Myr, the inner ∼1–10 kpc of the ISM is disrupted and the global galaxy star formation rate is significantly reduced. We quantify the properties of the resulting galaxy-scale outflows and find that the radial momentum in the outflow is boosted by a factor of ∼2–3 relative to that initially supplied in the AGN wind for strong feedback scenarios, decreasing below unity for less energetic winds. In contrast to observations, however, the outflows are primarily hot, with very little atomic or molecular gas. We conjecture that merging galaxies and high-redshift galaxies, which have more turbulent and thicker discs and very different nuclear gas geometries, may be even more disrupted by AGN winds than found in our simulations.

scholarly journals STUDYING THE INTERACTION BETWEEN MICROQUASAR JETS AND THEIR ENVIRONMENTS

2008 ◽  
Vol 17 (10) ◽  
pp. 1939-1945 ◽  
Author(s):  
M. PERUCHO ◽  
V. BOSCH-RAMON
Keyword(s):  
Binary System ◽  
Surrounding Medium ◽  
High Mass ◽  
Strong Interactions ◽  
Stellar Winds ◽  
Two Dimensional ◽  
Pressure Balance ◽  
Inverse Compton ◽  
Hydrodynamical Simulations ◽  
Accelerated Particles

In high-mass microquasars (HMMQ), strong interactions between jets and stellar winds at binary system scales could occur. In order to explore this possibility, we have performed numerical two-dimensional hydrodynamical simulations of jets crossing the dense stellar material to study how the jet will be affected by these interactions. We find that the jet head generates strong shocks in the wind. These shocks reduce the jet advance speed, and compress and heat up the jet and wind material. In addition, strong recollimation shocks can occur where pressure balance between the jet side and the surrounding medium is reached. All this, together with jet bending, could lead to the destruction of jets with power < 1036 erg/s . The conditions around the outflow shocks would be convenient for accelerating particles up to ~ TeV energies. These accelerated particles could emit via synchrotron and inverse Compton (IC) scattering if they were leptons, and via hadronic processes if they were hadrons.

scholarly journals The Cosmic Ballet III: halo spin evolution in the cosmic web

2021 ◽  
Author(s):  
Punyakoti Ganeshaiah Veena ◽  
Marius Cautun ◽  
Rien van de Weygaert ◽  
Elmo Tempel ◽  
Carlos S Frenk
Keyword(s):  
Initial Conditions ◽  
High Redshift ◽  
High Mass ◽  
Thin Filaments ◽  
Web Environment ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Halo Masses ◽  
First Time ◽  
Environmental Dependence

Abstract We explore the evolution of halo spins in the cosmic web using a very large sample of dark matter haloes in the ΛCDM Planck-Millennium N-body simulation. We use the nexus+ multiscale formalism to identify the hierarchy of filaments and sheets of the cosmic web at several redshifts. We find that at all times the magnitude of halo spins correlates with the web environment, being largest in filaments, and, for the first time, we show that it also correlates with filament thickness as well as the angle between spin-orientation and the spine of the host filament. For example, massive haloes in thick filaments spin faster than their counterparts in thin filaments, while for low-mass haloes the reverse is true. We also have studied the evolution of alignment between halo spin orientations and the preferential axes of filaments and sheets. The alignment varies with halo mass, with the spins of low-mass haloes being predominantly along the filament spine, while those of high-mass haloes being predominantly perpendicular to the filament spine. On average, for all halo masses, halo spins become more perpendicular to the filament spine at later times. At all redshifts, the spin alignment shows a considerable variation with filament thickness, with the halo mass corresponding to the transition from parallel to perpendicular alignment varying by more than one order of magnitude. The cosmic web environmental dependence of halo spin magnitude shows little evolution for z ≤ 2 and is likely a consequence of the correlations in the initial conditions or high redshift effects.

scholarly journals The Black Hole Mass Function Across Cosmic Times. I. Stellar Black Holes and Light Seed Distribution

2022 ◽  
Vol 924 (2) ◽  
pp. 56
Author(s):  
Alex Sicilia ◽  
Andrea Lapi ◽  
Lumen Boco ◽  
Mario Spera ◽  
Ugo N. Di Carlo ◽  
...  
Keyword(s):  
Black Hole ◽  
High Redshift ◽  
Mass Function ◽  
Stellar Mass ◽  
High Mass ◽  
Minor Effect ◽  
Density Parameter ◽  
Starting Point ◽  
Seed Distribution ◽  
The Impact

Abstract This is the first paper in a series aimed at modeling the black hole (BH) mass function, from the stellar to the intermediate to the (super)massive regime. In the present work, we focus on stellar BHs and provide an ab initio computation of their mass function across cosmic times; we mainly consider the standard, and likely dominant, production channel of stellar-mass BHs constituted by isolated single/binary star evolution. Specifically, we exploit the state-of-the-art stellar and binary evolutionary code SEVN, and couple its outputs with redshift-dependent galaxy statistics and empirical scaling relations involving galaxy metallicity, star formation rate and stellar mass. The resulting relic mass function dN / dVd log m • as a function of the BH mass m • features a rather flat shape up to m • ≈ 50 M ⊙ and then a log-normal decline for larger masses, while its overall normalization at a given mass increases with decreasing redshift. We highlight the contribution to the local mass function from isolated stars evolving into BHs and from binary stellar systems ending up in single or binary BHs. We also include the distortion on the mass function induced by binary BH mergers, finding that it has a minor effect at the high-mass end. We estimate a local stellar BH relic mass density of ρ • ≈ 5 × 107 M ⊙ Mpc−3, which exceeds by more than two orders of magnitude that in supermassive BHs; this translates into an energy density parameter Ω• ≈ 4 × 10−4, implying that the total mass in stellar BHs amounts to ≲1% of the local baryonic matter. We show how our mass function for merging BH binaries compares with the recent estimates from gravitational wave observations by LIGO/Virgo, and discuss the possible implications for dynamical formation of BH binaries in dense environments like star clusters. We address the impact of adopting different binary stellar evolution codes (SEVN and COSMIC) on the mass function, and find the main differences to occur at the high-mass end, in connection with the numerical treatment of stellar binary evolution effects. We highlight that our results can provide a firm theoretical basis for a physically motivated light seed distribution at high redshift, to be implemented in semi-analytic and numerical models of BH formation and evolution. Finally, we stress that the present work can constitute a starting point to investigate the origin of heavy seeds and the growth of (super)massive BHs in high-redshift star-forming galaxies, that we will pursue in forthcoming papers.

scholarly journals Supernova feedback and the energy deposition in molecular clouds

2020 ◽  
Vol 493 (4) ◽  
pp. 4700-4710 ◽  
Author(s):  
William E Lucas ◽  
Ian A Bonnell ◽  
James E Dale
Keyword(s):  
Galaxy Formation ◽  
Supernova Explosion ◽  
High Mass ◽  
Stellar Winds ◽  
Mass Star ◽  
Stellar Feedback ◽  
The Galaxy ◽  
Weak Points ◽  
Supernova Explosions ◽  
Supernova Feedback

Abstract Feedback from supernovae is often invoked as an important process in limiting star formation, removing gas from galaxies and, hence, as a determining process in galaxy formation. Here, we report on numerical simulations, investigating the interaction between supernova explosions and the natal molecular cloud. We also consider the cases with and without previous feedback from the high-mass star in the form of ionizing radiation and stellar winds. The supernova is able to find weak points in the cloud and creates channels through which it can escape, leaving much of the well-shielded cloud largely unaffected. This effect is increased when the channels are preexisting due to the effects of previous stellar feedback. The expanding supernova deposits its energy in the gas that is in these exposed channels, and, hence, sweeps up less mass when feedback has already occurred, resulting in faster outflows with less radiative losses. The full impact of the supernova explosion is then able to impact the larger scale of the galaxy in which it abides. We conclude that supernova explosions have only moderate effects on their dense natal environments but that with preexisting feedback, the energetic effects of the supernova are able to escape and affect the wider scale medium of the galaxy.

scholarly journals A comparison of H2 formation models at high redshift

2020 ◽  
Vol 497 (4) ◽  
pp. 5008-5023 ◽  
Author(s):  
Alexander Schäbe ◽  
Emilio Romano-Díaz ◽  
Cristiano Porciani ◽  
Aaron D Ludlow ◽  
Matteo Tomassetti
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Empirical Method ◽  
High Mass ◽  
Rate Equations ◽  
Approximate Methods ◽  
Ab Initio Simulations ◽  
H2 Formation ◽  
Semi Empirical ◽  
The Impact

ABSTRACT Modelling the molecular gas that is routinely detected through CO observations of high-redshift galaxies constitutes a major challenge for ab initio simulations of galaxy formation. We carry out a suite of cosmological hydrodynamic simulations to compare three approximate methods that have been used in the literature to track the formation and evolution of the simplest and most abundant molecule, H2. Namely, we consider (i) a semi-empirical procedure that associates H2 to dark-matter haloes based on a series of scaling relations inferred from observations, (ii) a model that assumes chemical equilibrium between the H2 formation and destruction rates, and (iii) a model that fully solves the out-of-equilibrium rate equations and accounts for the unresolved structure of molecular clouds. We study the impact of finite spatial resolution and show that robust H2 masses at redshift $z$ ≈ 4 can only be obtained for galaxies that are sufficiently metal enriched in which H2 formation is fast. This corresponds to H2 reservoirs with masses $M_{\mathrm{H_2}}\gtrsim 6\times 10^9$ M⊙. In this range, equilibrium and non-equilibrium models predict similar molecular masses (but different galaxy morphologies) while the semi-empirical method produces less H2. The star formation rates as well as the stellar and H2 masses of the simulated galaxies are in line with those observed in actual galaxies at similar redshifts that are not massive starbursts. The H2 mass functions extracted from the simulations at $z$ ≈ 4 agree well with recent observations that only sample the high-mass end. However, our results indicate that most molecular material at high $z$ lies yet undetected in reservoirs with $10^9\lt M_{\mathrm{H}_2}\lt 10^{10}$ M⊙.

The Local Group Dwarf Spheroidal Galaxies: A Key to Building Blocks in the Universe

2005 ◽  
Vol 201 ◽  
pp. 469-470
Author(s):  
Hiroyuki. Hirashita ◽  
Naoyuki. Tamura ◽  
Tsutomu T. Takeuchi
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Building Blocks ◽  
Star Formation History ◽  
High Mass ◽  
Dwarf Spheroidal Galaxies ◽  
The Hierarchical Structure ◽  
History Of ◽  
Low Mass ◽  
Spheroidal Galaxies

Recent studies have been revealing the properties of dwarf spheroidal galaxies (dSphs). Their low mass indicates that the dSphs may provide a clue to physical properties of the building blocks in the hierarchical structure formation. We select the Local Group dSphs as a sample. To obtain the information on the star formation history of dSphs, we investigate the relation between their metallicity and virial mass. According to our scenario, the star formation efficiency of the dSphs is low because of strong regulation. This is consistent with their high mass-to-light ratios. We also comment on the environmental effects on the dSphs.

scholarly journals Simulating High-Redshift Disk Galaxies: Applications to Long Duration Gamma-Ray Burst Hosts

2008 ◽  
Vol 4 (S254) ◽  
pp. 35-40
Author(s):  
Brant E. Robertson
Keyword(s):  
Star Formation ◽  
Molecular Hydrogen ◽  
Gamma Ray ◽  
High Redshift ◽  
Disk Galaxies ◽  
Host Galaxies ◽  
Long Duration ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
The Impact

AbstractThe efficiency of star formation governs many observable properties of the cosmological galaxy population, yet many current models of galaxy formation largely ignore the important physics of star formation and the interstellar medium (ISM). Using hydrodynamical simulations of disk galaxies that include a treatment of the molecular ISM and star formation in molecular clouds (Robertson & Kravtsov 2008), we study the influence of star formation efficiency and molecular hydrogen abundance on the properties of high-redshift galaxy populations. In this work, we focus on a model of low-mass, star forming galaxies at 1 ≲ z ≲ 2 that may host long duration gamma-ray bursts (GRBs). Observations of GRB hosts have revealed a population of faint systems with star formation properties that often differ from Lyman-break galaxies (LBGs) and more luminous high-redshift field galaxies. Observed GRB sightlines are deficient in molecular hydrogen, but it is unclear to what degree this deficiency owes to intrinsic properties of the galaxy or the impact the GRB has on its environment. We find that hydrodynamical simulations of low-stellar mass systems at high-redshifts can reproduce the observed star formation rates and efficiencies of GRB host galaxies at redshifts 1 ≲ z ≲ 2. We show that the compact structure of low-mass high-redshift GRB hosts may lead to a molecular ISM fraction of a few tenths, well above that observed in individual GRB sightlines. However, the star formation rates of observed GRB host galaxies imply molecular gas masses of 108 – 109M⊙ similar to those produced in the simulations, and may therefore imply fairly large average H2 fractions in their ISM.

scholarly journals Feedback from OB stars on their parent cloud: gas exhaustion rather than gas ejection

2019 ◽  
Vol 628 ◽  
pp. A21 ◽  
Author(s):  
E. J. Watkins ◽  
N. Peretto ◽  
K. Marsh ◽  
G. A. Fuller
Keyword(s):  
Theoretical Calculations ◽  
Unit Length ◽  
Gravitational Energy ◽  
Star Formation History ◽  
High Mass ◽  
Evolutionary Stage ◽  
Dark Part ◽  
Star Forming ◽  
Stellar Feedback ◽  
Hydrodynamical Simulations

Context. Stellar feedback from high-mass stars shapes the interstellar medium, and thereby impacts gas that will form future generations of stars. However, due to our inability to track the time evolution of individual molecular clouds, quantifying the exact role of stellar feedback on their star formation history is an observationally challenging task. Aims. In the present study, we take advantage of the unique properties of the G316.75-00.00 massive-star forming ridge to determine how stellar feedback from O-stars impacts the dynamical stability of massive filaments. The G316.75 ridge is 13.6 pc long and contains 18 900 M⊙ of H2 gas, half of which is infrared dark and half of which infrared bright. The infrared bright part has already formed four O-type stars over the past 2 Myr, while the infrared dark part is still quiescent. Therefore, by assuming the star forming properties of the infrared dark part represent the earlier evolutionary stage of the infrared bright part, we can quantify how feedback impacts these properties by contrasting the two. Methods. We used publicly available Herschel/HiGAL and molecular line data to measure the ratio of kinetic to gravitational energy per-unit-length, αvirline, across the entire ridge. By using both dense (i.e. N2H+ and NH3) and more diffuse (i.e. 13CO) gas tracers, we were able to compute αvirline for a range of gas volume densities (~1 × 102–1 × 105 cm−3). Results. This study shows that despite the presence of four embedded O-stars, the ridge remains gravitationally bound (i.e. αvirline ≤ 2) nearly everywhere, except for some small gas pockets near the high-mass stars. In fact, αvirline is almost indistinguishable for both parts of the ridge. These results are at odds with most hydrodynamical simulations in which O-star-forming clouds are completely dispersed by stellar feedback within a few cloud free-fall times. However, from simple theoretical calculations, we show that such feedback inefficiency is expected in the case of high-gas-density filamentary clouds. Conclusions. We conclude that the discrepancy between numerical simulations and the observations presented here originates from different cloud morphologies and average densities at the time when the first O-stars form. In the case of G316.75, we speculate that the ridge could arise from the aftermath of a cloud-cloud collision, and that such filamentary configuration promotes the inefficiency of stellar feedback. This does very little to the dense gas already present, but potentially prevents further gas accretion onto the ridge. These results have important implications regarding, for instance, how stellar feedback is implemented in cosmological and galaxy scale simulations.

Sign in / Sign up

Export Citation Format

Share Document