scholarly journals Numerical Simulations of High‐Redshift Star Formation in Dwarf Galaxies

2003 ◽  
Vol 587 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Konstantinos Tassis ◽  
Tom Abel ◽  
Greg L. Bryan ◽  
Michael L. Norman
Keyword(s):  
Star Formation ◽  
Numerical Simulations ◽  
Dwarf Galaxies ◽  
High Redshift

Star formation at low rates: impact of lacking massive stars on the evolution of dwarf galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 186-189
Author(s):  
P. Steyrleithner ◽  
G. Hensler ◽  
S. Recchi ◽  
S. Ploeckinger
Keyword(s):  
Star Formation ◽  
Numerical Simulations ◽  
Galaxy Evolution ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
Self Regulation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Single Star ◽  
The Imf

AbstractIn recent years dedicated observations have uncovered star formation at extremely low rates in dwarf galaxies, tidal tails, ram-pressure stripped gas clouds, and the outskirts of galactic disks. At the same time, numerical simulations of galaxy evolution have advanced to higher spatial and mass resolutions, but have yet to account for the underfilling of the uppermost mass bins of stellar initial mass function (IMF) at low star-formation rates. In such situations, simulations may simply scale down the IMF, without realizing that this unrealistically results in fractions of massive stars, along with fractions of massive star feedback energy (e.g., radiation and SNII explosions). Not properly accounting for such parameters has consequences for the self-regulation of star formation, the energetics of galaxies, as well as for the evolution of chemical abundances. Here we present numerical simulations of dwarf galaxies with low star-formation rates allowing for two extreme cases of the IMF: a “filled” case with fractional massive stars vs. a truncated IMF, at which the IMF is built bottom-up until the gas reservoir allows the formation of a last single star at an uppermost mass. The aim of the study is to demonstrate the different effects on galaxy evolution with respect to self-regulation, feedback, and chemistry. The case of a stochastic sampled IMF is situated somewhere in between these extremes.

scholarly journals Tidal dwarf galaxies as laboratories of star formation and cosmology

2006 ◽  
Vol 2 (S237) ◽  
pp. 323-330 ◽  
Author(s):  
Pierre-Alain Duc ◽  
Frédéric Bournaud ◽  
Médéric Boquien
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Numerical Simulations ◽  
Dwarf Galaxies ◽  
Star Clusters ◽  
Dense Core ◽  
Multi Wavelength ◽  
Interacting Systems ◽  
Super Star Clusters ◽  
Tidal Tails

AbstractStar formation may take place in a variety of locations in interacting systems: in the dense core of mergers, in the shock regions at the interface of the colliding galaxies and even within the tidal debris expelled into the intergalactic medium. Along tidal tails, objects may be formed with masses ranging from those of super-star clusters to dwarf galaxies: the so-called Tidal Dwarf Galaxies (TDGs). Based on a set of multi-wavelength observations and extensive numerical simulations, we show how TDGs may simultaneously be used as laboratories to study the process of star-formation (SFE, IMF) in a specific environment and as probes of various cosmological properties, such as the distribution of dark matter and satellites around galaxies.

scholarly journals Local Analogs to High-redshift Galaxies. I. Characterization of Dust Emission and Star Formation History

2021 ◽  
Vol 921 (2) ◽  
pp. 130
Author(s):  
Skarleth M. Motiño Flores ◽  
Tommy Wiklind ◽  
Rafael T. Eufrasio
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Star Formation History ◽  
Spectral Energy ◽  
High Redshift Galaxies ◽  
Star Formation Activity ◽  
Look Back ◽  
Redshift Galaxies

Abstract Star-forming dwarf galaxies have properties similar to those expected in high-redshift galaxies. Hence, these local galaxies may provide insights into the evolution of the first galaxies and the physical processes at work. We present a sample of 11 potential local analogs to high-z (LAHz) galaxies. The sample consists of blue compact dwarf galaxies, selected to have spectral energy distributions that fit galaxies at 1.5 < z < 4. We use SOFIA-HAWC+ observations combined with optical and near-infrared data to characterize the dust properties, star formation rate (SFR), and star formation histories (SFHs) of the sample of LAHz galaxies. We employ Bayesian analysis to characterize the dust using two-component blackbody models. Using the Lightning package, we fit the spectral energy distribution of the LAHz galaxies over the far-UV−far-infrared wavelength range and derive the SFH in five time steps up to a look-back time of 13.3 Gyr. Of the 11 LAHz candidates, six galaxies have SFH consistent with no star formation activity at look-back times beyond 1 Gyr. The remaining galaxies show residual levels of star formation at ages ≳1 Gyr, making them less suitable as local analogs. The six young galaxies stand out in our sample by having the lowest gas-phase metallicities. They are characterized by warmer dust, having the highest specific SFR and the highest gas mass fractions. The young age of these six galaxies suggests that merging is less important as a driver of the star formation activity. The six LAHz candidates are promising candidates for studies of the gasdynamics role in driving star formation.

scholarly journals Dwarf Galaxies: From the Epoch of Peak Star Formation to the Epoch of Reionization

2018 ◽  
Vol 14 (S344) ◽  
pp. 429-436
Author(s):  
Hakim Atek
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
Great Part ◽  
Star Formation History ◽  
Dark Matter Halos ◽  
Galaxy Surveys ◽  
Formation History ◽  
History Of ◽  
Low Mass

AbstractDwarf galaxies represent the dominant population at high redshift and they most likely contributed in great part to star formation history of the Universe and cosmic reionization. The importance of dwarf galaxies at high redshift has been mostly recognized in the last decade due to large progress in observing facilities allowing deep galaxy surveys to identify low-mass galaxies. This population appear to have extreme emission lines and ionizing properties that challenge stellar population models. Star formation follows a stochastic process in these galaxies, which has important implication on the ionizing photon production and its escape fraction whose measurements are challenging for both simulations and observations. Outstanding questions include: what are the physical properties at the origin of such extreme properties? What are the smallest dark matter halos that host star formation? Are dwarf galaxies responsible for cosmic reionization?

scholarly journals On the origin of nitrogen at low metallicity

2021 ◽  
Vol 502 (3) ◽  
pp. 4359-4376
Author(s):  
Arpita Roy ◽  
Michael A Dopita ◽  
Mark R Krumholz ◽  
Lisa J Kewley ◽  
Ralph S Sutherland ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
High Redshift ◽  
Large Scatter ◽  
Abundance Distribution ◽  
Abundance Patterns ◽  
M 10 ◽  
Low Metallicity ◽  
Formation Efficiency

ABSTRACT Understanding the evolution of the N/O ratio in the interstellar medium (ISM) of galaxies is essential if we are to complete our picture of the chemical evolution of galaxies at high redshift, since most observational calibrations of O/H implicitly depend upon the intrinsic N/O ratio. The observed N/O ratio, however, shows large scatter at low O/H, and is strongly dependent on galactic environment. We show that several heretofore unexplained features of the N/O distribution at low O/H can be explained by the N seen in metal-poor galaxies being mostly primary nitrogen that is returned to the ISM via pre-supernova winds from rapidly rotating massive stars (M ≳ 10 M⊙, v/vcrit ≳ 0.4). This mechanism naturally produces the observed N/O plateau at low O/H. We show that the large scatter in N/O at low O/H also arises naturally from variations in star-formation efficiency. By contrast, models in which the N and O come primarily from supernovae provide a very poor fit to the observed abundance distribution. We propose that the peculiar abundance patterns we observe at low O/H are a signature that dwarf galaxies retain little of their SN ejecta, leaving them with abundance patterns typical of winds.

scholarly journals The stellar populations of high-redshift dwarf galaxies

2020 ◽  
Vol 498 (3) ◽  
pp. 4134-4149
Author(s):  
V Gelli ◽  
S Salvadori ◽  
A Pallottini ◽  
A Ferrara
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Populations ◽  
High Mass ◽  
Evolutionary Patterns ◽  
Chemical Enrichment ◽  
Stellar Feedback

ABSTRACT We use high-resolution (≈10 pc), zoom-in simulations of a typical (stellar mass $M_\star \simeq 10^{10}\, {\rm M}_{\odot }$) Lyman Break Galaxy (LBG) at z ≃ 6 to investigate the stellar populations of its six dwarf galaxy satellites, whose stellar [gas] masses are in the range log (M⋆/M⊙) ≃ 6−9 [log (Mgas/M⊙) ≃ 4.3−7.75]. The properties and evolution of satellites show no dependence on the distance from the central massive LBG (&lt;11.5 kpc). Instead, their star formation and chemical enrichment histories are tightly connected to their stellar (and sub-halo) mass. High-mass dwarf galaxies ($M_\star \gtrsim 5\times 10^8 \, {\rm M}_{\odot }$) experience a long history of star formation, characterized by many merger events. Lower mass systems go through a series of short star formation episodes, with no signs of mergers; their star formation activity starts relatively late (z ≈ 7), and it is rapidly quenched by internal stellar feedback. In spite of the different evolutionary patterns, all satellites show a spherical morphology, with ancient and more metal-poor stars located towards the inner regions. All six dwarf satellites experienced high star formation rate ($\rm \gt 5\, {\rm M}_{\odot }\, {\rm yr}^{-1}$) bursts, which can be detected by James Webb Space Telescope while targeting high-z LBGs.

Dwarf galaxies at low and high redshift

2018 ◽  
Vol 14 (S344) ◽  
pp. 437-445
Author(s):  
Xu Kong ◽  
Jianhui Lian ◽  
Yulong Gao ◽  
Zuyi Chen ◽  
Guangwen Chen ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Mass Star ◽  
Chemical Enrichment ◽  
Galaxy Sample

AbstractThe overwhelming majority of galaxies in the Universe are dwarf galaxies. But although they are important components in understanding galaxy evolution, these systems are typically too faint to be observed at high redshifts. However, we are able to obtain an unobscured view of early star formation and chemical enrichment in these galaxies at low redshift and low-redshift analogs at high redshift. In this talk, I will review the mass-metallicity relation, the mass-star formation rate relation of galaxies, the classifications of dwarf galaxies, and the importance of dwarf galaxies for both astronomy and physics. Then I will introduce some work in our group on connections among between different types of dwarf galaxies,the mass-metallicity relations and the main sequence relations of dwarf galaxies, using the deep optical and near infrared images and spectra of large dwarf galaxy sample. At the end, I will talk about some projects of dwarf galaxies we are working on, including the spectroscopic survey for compact dwarf galaxies using the LAMOST.

scholarly journals The gas, metal, and dust evolution in low-metallicity local and high-redshift galaxies

2020 ◽  
Vol 641 ◽  
pp. A168 ◽  
Author(s):  
A. Nanni ◽  
D. Burgarella ◽  
P. Theulé ◽  
B. Côté ◽  
H. Hirashita
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
High Redshift ◽  
Stellar Mass ◽  
Type Ii ◽  
Chemical Enrichment ◽  
Dust Mass ◽  
Low Metallicity ◽  
Dust Evolution

Context. The chemical enrichment in the interstellar medium (ISM) of galaxies is regulated by several physical processes: star birth and death, grain formation and destruction, and galactic inflows and outflows. Understanding such processes and their relative importance is essential to following galaxy evolution and the chemical enrichment through the cosmic epochs, and to interpreting current and future observations. Despite the importance of such topics, the contribution of different stellar sources to the chemical enrichment of galaxies, for example massive stars exploding as Type II supernovae (SNe) and low-mass stars, as well as the mechanisms driving the evolution of dust grains, such as for example grain growth in the ISM and destruction by SN shocks, remain controversial from both observational and theoretical viewpoints. Aims. In this work, we revise the current description of metal and dust evolution in the ISM of local low-metallicity dwarf galaxies and develop a new description of Lyman-break galaxies (LBGs) which are considered to be their high-redshift counterparts in terms of star formation, stellar mass, and metallicity. Our goal is to reproduce the observed properties of such galaxies, in particular (i) the peak in dust mass over total stellar mass (sMdust) observed within a few hundred million years; and (ii) the decrease in sMdust at a later time. Methods. We fitted spectral energy distribution of dwarf galaxies and LBGs with the “Code Investigating GALaxies Emission”, through which the total stellar mass, dust mass, and star formation rate are estimated. For some of the dwarf galaxies considered, the metal and gas content are available from the literature. We computed different prescriptions for metal and dust evolution in these systems (e.g. different initial mass functions for stars, dust condensation fractions, SN destruction, dust accretion in the ISM, and inflow and outflow efficiency), and we fitted the properties of the observed galaxies through the predictions of the models. Results. Only some combinations of models are able to reproduce the observed trend and simultaneously fit the observed properties of the galaxies considered. In particular, we show that (i) a top-heavy initial mass function that favours the formation of massive stars and a dust condensation fraction for Type II SNe of around 50% or more help to reproduce the peak of sMdust observed after ≈100 Myr from the beginning of the baryon cycle for both dwarf galaxies and LBGs; (ii) galactic outflows play a crucial role in reproducing the observed decline in sMdust with age and are more efficient than grain destruction from Type II SNe both in local galaxies and at high-redshift; (iii) a star formation efficiency (mass of gas converted into stars) of a few percent is required to explain the observed metallicity of local dwarf galaxies; and (iv) dust growth in the ISM is not necessary in order to reproduce the values of sMdust derived for the galaxies under study, and, if present, the effect of this process would be erased by galactic outflows.

scholarly journals Dark-ages Reionization and Galaxy Formation Simulation – XIV. Gas accretion, cooling, and star formation in dwarf galaxies at high redshift

2018 ◽  
Vol 477 (1) ◽  
pp. 1318-1335 ◽  
Author(s):  
Yuxiang Qin ◽  
Alan R Duffy ◽  
Simon J Mutch ◽  
Gregory B Poole ◽  
Paul M Geil ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
Dark Ages ◽  
Gas Accretion
Sign in / Sign up

Export Citation Format

Share Document