scholarly journals The Role of Massive Stars in Galactic Chemical Evolution

2007 ◽  
Vol 3 (S250) ◽  
pp. 391-400 ◽  
Author(s):  
Francesca Matteucci
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Massive Stars ◽  
High Redshift ◽  
Morphological Type ◽  
Mass Relation ◽  
Delay Model ◽  
Galactic Winds ◽  
Dwarf Spheroidals

AbstractI will review the role of massive stars in galactic evolution both from the nucleosynthesis and energetics point of view. In particular, I will highlight some important observational facts explained by means of massive stars in galaxies of different morphological type: the Milky Way, ellipticals and dwarf spheroidals. I will describe first the time-delay model and its interpretation in terms of abundance ratios in galaxies, then I will discuss the importance of mass loss in massive stars to reproduce the data in the Galactic bulge and disk. I will discuss also how massive stars can be important producers of primary nitrogen if rotation in stellar models is taken into account. Concerning elliptical galaxies, I will show that to reproduce the observed [Mg/Fe] versus Mass relation in these galaxies it is necessary to assume a more important role of massive stars in more massive galaxies and that this can be achieved by means of downsizing in star formation. I will discuss how massive stars are responsible in triggering galactic winds both in ellipticals and dwarf spheroidals. These latter systems show a low overabundance of α-elements relative to Fe with respect to Galactic stars of the same [Fe/H]: this is interpreted as due to a slow star formation coupled with very efficient galactic winds. Finally, I will show a comparison between the predicted Type Ib/c rates in galaxies and the observed GRB rate and how we can impose constraints on the mechanism of galaxy formation by studying the GRB rate at high redshift.

scholarly journals Quasi-equilibrium models of high-redshift disc galaxy evolution

2020 ◽  
Vol 500 (3) ◽  
pp. 3394-3412
Author(s):  
Steven R Furlanetto
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
New Physics ◽  
Small Scale ◽  
Quasi Equilibrium ◽  
Mass Relation ◽  
Disc Galaxy

ABSTRACT In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude connections to the physics of galaxy evolution. Here, we introduce a set of galaxy models that are based on a simple physical framework but incorporate more sophisticated models of feedback, star formation, and other processes. We apply these models to the high-redshift regime, showing that most of the generic predictions of the simplest models remain valid. In particular, the stellar mass–halo mass relation depends almost entirely on the physics of feedback (and is thus independent of the details of small-scale star formation) and the specific star formation rate is a simple multiple of the cosmological accretion rate. We also show that, in contrast, the galaxy’s gas mass is sensitive to the physics of star formation, although the inclusion of feedback-driven star formation laws significantly changes the naive expectations. While these models are far from detailed enough to describe every aspect of galaxy formation, they inform our understanding of galaxy formation by illustrating several generic aspects of that process, and they provide a physically grounded basis for extrapolating predictions to faint galaxies and high redshifts currently out of reach of observations. If observations show violations from these simple trends, they would indicate new physics occurring inside the earliest generations of galaxies.

scholarly journals Outflows from ellipticals: the role of supernovae

2003 ◽  
Vol 212 ◽  
pp. 630-636
Author(s):  
Francesca Matteucci ◽  
Antonio Pipino
Keyword(s):  
Star Formation ◽  
Dominant Role ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Type Ii ◽  
Chemical Enrichment ◽  
Galactic Winds ◽  
Type Ia ◽  
Intense Burst

Models of supernova (SN) driven galactic winds for ellipticals are presented. We assume that ellipticals formed at high redshift and suffered an intense burst of star formation. The role of supernovae of Type II and Type Ia in the chemical enrichment and in triggering galactic winds is studied. In particular, several recipes for SN feed-back together with detailed nucleosynthesis prescriptions are considered. It is shown that SNe of Type II have a dominant role in enriching the interstellar medium of elliptical galaxies whereas Type Ia SNe dominate the enrichment and the energetics of the intracluster medium.

scholarly journals Implications of Early Cooling Flows and Galactic Winds for the Evolution of Deuterium

2000 ◽  
Vol 198 ◽  
pp. 535-539
Author(s):  
Amancio C. S. Friaça
Keyword(s):  
Absorption Line ◽  
Galaxy Formation ◽  
Spatial Scales ◽  
High Redshift ◽  
Cooling Flows ◽  
Galactic Winds ◽  
Important Constraint

The deuterium abundances in high-redshift QSO absorption-line systems could be an important constraint in models of galaxy formation. Here we investigate the role of galactic winds and massive cooling flows present during the formation of galaxies on the evolution of deuterium abundance. Destruction factors are calculated and the time and spatial scales for the dispersal through galactic winds of the processed deuterium-depleted gas are presented and related to the D/H determinations for QSO absorption-line systems. The calculations are derived from a chemodynamical model within a scenario in which the absorbers are located inside the hot halo of a young galaxy.

scholarly journals The roles of atomic and molecular gas on the redshift evolution of star formation and metallicity in galaxy formation models

2012 ◽  
Vol 8 (S292) ◽  
pp. 245-245
Author(s):  
Jian Fu ◽  
Guinevere Kauffmann
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Time Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Formation Time ◽  
Model Parameters ◽  
Molecular Gas ◽  
Mass Relation

AbstractWe study the redshift evolution of neutral and molecular gas in the interstellar medium with the results from semi-analytic models of galaxy formation and evolution, which track the cold gas related physical processes in radially resolved galaxy disks. Two kinds of prescriptions are adopted to describe the conversion between molecular and neutral gas in the ISM: one is related to the gas surface density and gas metallicity based on the model results by Krumholz, Mckee & Tumlinson; the other is related the pressure of ISM. We try four types of star formation laws in the models to study the effect of the molecular gas component and the star formation time scale on the model results, and find that the H2 dependent star formation rate with constant star formation efficiency is the preferred star formation law. We run the models based on both Millennium and Millennium II Simulation haloes, and the model parameters are adjusted to fit the observations at z = 0 from THINGS/HERACLES and ALFALFA/COLD GASS. We give predictions for the redshift evolution of cosmic star formation density, H2 to HI cosmic ratios, gas to star mass ratios and gas metallicity vs stellar mass relation. Based on the model results, we find that: (i) the difference in the H2 to HI ratio at z > 3 between the two H2 fraction prescriptions can help future observations to test which prescription is better; (ii) a constant redshift independent star formation time scale will postpone the star formation processes at high redshift and cause obvious redshift evolution for the relation between gas metallicity and stellar mass in galaxies at z < 3.

scholarly journals Star Formation at High Redshift

1992 ◽  
Vol 45 (4) ◽  
pp. 389
Author(s):  
Colin A Norman
Keyword(s):  
Star Formation ◽  
Absorption Line ◽  
Galaxy Formation ◽  
Massive Star ◽  
High Redshift ◽  
Radio Galaxies ◽  
Starburst Galaxies ◽  
Active Galaxies ◽  
Massive Star Formation

The observations relevant to star formation at high redshift are reviewed including radio galaxies, quasars, IRAS objects, and QSO emission and absorption line regions. Low redshift counterparts associated with starburst galaxies are discussed. The relation of galaxy formation, starbursts, and active galaxies and quasars is briefly reviewed. The role of feedback in galaxy formation and massive star formation is briefly analysed.

scholarly journals What Can We Learn from the Local Group About the Role of Interactions in Galaxy Formation

1999 ◽  
Vol 186 ◽  
pp. 23-29
Author(s):  
K.C. Freeman
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Milky Way ◽  
Local Group ◽  
High Redshift ◽  
Dissipative Process ◽  
Active Star ◽  
Flat Systems ◽  
Active Star Formation

This talk is mainly about the halos and bulges of Local Group galaxies, in particular those of the Milky Way and M31, and what they can tell us about the role of interactions in galaxy formation. Bulges are potentially of particular interest for galaxy formation because they are widely suspected to be the seeds for galaxy formation. Sites of active star formation at high redshift are often regarded as spheroids in the process of formation. In this talk, I will say little about disks because their formation is conceptually understood, although many details remain uncertain. To form such flat systems, a fairly undisturbed dissipative process is needed. This process occurred fairly early: the disks appear to be in place by a redshift z = 1 (Ellis 1997), with a distribution of scalelengths that is similar to the distribution at z = 0.

scholarly journals EDGE: a new approach to suppressing numerical diffusion in adaptive mesh simulations of galaxy formation

2020 ◽  
Vol 501 (2) ◽  
pp. 1755-1765
Author(s):  
Andrew Pontzen ◽  
Martin P Rey ◽  
Corentin Cadiou ◽  
Oscar Agertz ◽  
Romain Teyssier ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Initial Conditions ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Morphological Structure ◽  
Adaptive Mesh ◽  
Numerical Diffusion

ABSTRACT We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the ‘EDGE’ project. The target galaxy has a maximum circular velocity of $21\, \mathrm{km}\, \mathrm{s}^{-1}$ but evolves in a region that is moving at up to $90\, \mathrm{km}\, \mathrm{s}^{-1}$ relative to the hydrodynamic grid. In the absence of any mitigation, diffusion softens the filaments feeding our galaxy. As a result, gas is unphysically held in the circumgalactic medium around the galaxy for $320\, \mathrm{Myr}$, delaying the onset of star formation until cooling and collapse eventually triggers an initial starburst at z = 9. Using genetic modification, we produce ‘velocity-zeroed’ initial conditions in which the grid-relative streaming is strongly suppressed; by design, the change does not significantly modify the large-scale structure or dark matter accretion history. The resulting simulation recovers a more physical, gradual onset of star formation starting at z = 17. While the final stellar masses are nearly consistent ($4.8 \times 10^6\, \mathrm{M}_{\odot }$ and $4.4\times 10^6\, \mathrm{M}_{\odot }$ for unmodified and velocity-zeroed, respectively), the dynamical and morphological structure of the z = 0 dwarf galaxies are markedly different due to the contrasting histories. Our approach to diffusion suppression is suitable for any AMR zoom cosmological galaxy formation simulations, and is especially recommended for those of small galaxies at high redshift.

scholarly journals Populations of OB-type stars in galaxies

2010 ◽  
Vol 6 (S272) ◽  
pp. 233-241
Author(s):  
Christopher J. Evans
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Spectral Synthesis ◽  
High Redshift ◽  
Young Star ◽  
Magellanic Clouds ◽  
Star Forming ◽  
The Galaxy ◽  
External Galaxies

AbstractOne of the challenges for stellar astrophysics is to reach the point at which we can undertake reliable spectral synthesis of unresolved populations in young, star-forming galaxies at high redshift. Here I summarise recent studies of massive stars in the Galaxy and Magellanic Clouds, which span a range of metallicities commensurate with those in high-redshift systems, thus providing an excellent laboratory in which to study the role of environment on stellar evolution. I also give an overview of observations of luminous supergiants in external galaxies out to a remarkable 6.7 Mpc, in which we can exploit our understanding of stellar evolution to study the chemistry and dynamics of the host systems.

scholarly journals Line-driven ablation of circumstellar discs – IV. The role of disc ablation in massive star formation and its contribution to the stellar upper mass limit

2018 ◽  
Vol 483 (4) ◽  
pp. 4893-4900 ◽  
Author(s):  
Nathaniel Dylan Kee ◽  
Rolf Kuiper
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Loss Rate ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Ablation Rate ◽  
Massive Star Formation ◽  
Future Studies ◽  
Accretion Rates

Abstract Radiative feedback from luminous, massive stars during their formation is a key process in moderating accretion on to the stellar object. In the prior papers in this series, we showed that one form such feedback takes is UV line-driven disc ablation. Extending on this study, we now constrain the strength of this effect in the parameter range of star and disc properties appropriate to forming massive stars. Simulations show that ablation rate depends strongly on stellar parameters, but that this dependence can be parameterized as a nearly constant, fixed enhancement over the wind mass-loss rate, allowing us to predict the rate of disc ablation for massive (proto)stars as a function of stellar mass and metallicity. By comparing this to predicted accretion rates, we conclude that ablation is a strong feedback effect for very massive (proto)stars which should be considered in future studies of massive star formation.

scholarly journals Angular Momentum Transfer Due to Galactic Winds and Cooling Flows

1999 ◽  
Vol 186 ◽  
pp. 201-201
Author(s):  
V. Missoulis
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Momentum Transfer ◽  
Galaxy Formation ◽  
Cooling Flows ◽  
Galactic Wind ◽  
Angular Momentum Transfer ◽  
Early Stages ◽  
Galactic Winds ◽  
Gaseous Envelope

We examine a model of galaxy formation where the bulge is formed at very early stages and this burst of star formation leads to a galactic wind which interacts with a huge surrounding gaseous envelope.

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