scholarly journals The chemical evolution of dwarf starburst galaxies

1999 ◽  
Vol 193 ◽  
pp. 679-691
Author(s):  
Francesca Matteucci ◽  
Annibale D'Ercole
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Chemical Evolution ◽  
Starburst Galaxies ◽  
Star Formation History ◽  
H Ii Regions ◽  
Dark Matter Halos ◽  
Star Formation Activity ◽  
Irregular Galaxies ◽  
Formation History

We will review the most popular models for the chemical evolution of some starburst galaxies, in particular dwarf irregular galaxies. These galaxies are relatively simple and unevolved objects with low metallicities and large gas contents, suggesting that they are either young or have undergone discontinuous star formation activity. Some dwarf irregulars are starburst galaxies currently experiencing an intense star formation event and they are known as blue compact galaxies or extragalactic H II regions. We will discuss the effects of the presence of dark matter halos together with stellar energetics (stellar winds and supernovae) on the development of a galactic wind in these systems. Particular emphasis will be given to the role of massive stars in driving the thermal and chemical evolution of the gas, in particular to type II supernovae. A comparison between different model predictions for abundances and abundance ratios will be used to impose constraints on the star formation history and on the amount of dark matter, which we found to be extremely important in these systems.

scholarly journals The size-density relation of H ii regions in blue compact dwarf galaxies

2008 ◽  
Vol 4 (S255) ◽  
pp. 361-365
Author(s):  
Hiroyuki Hirashita ◽  
Leslie K. Hunt
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Star Formation History ◽  
H Ii Regions ◽  
Scale Free ◽  
Dust Extinction ◽  
Star Formation Activity ◽  
Formation History ◽  
Density Relation ◽  
Low Metallicity

AbstractWe investigate the size-density relation of H ii regions in blue compact dwarf galaxies (BCDs) by compiling observational data of their size (Di) and electron density (ne). We find that the size-density relation follows a relation with constant column density (ne ∝ Di−1) rather than with constant luminosity (ne ∝ Di−1.5). Such behavior resembles that of Galactic H ii regions, and may imply an underlying “scale-free” connection. Because this size-density relation cannot be explained by static models, we model and examine the evolution of the size-density relation of H ii regions by considering the star formation history and pressure-driven expansion of H ii regions. We find that the size-density relation of the entire BCD sample does not result from an evolutionary sequence of H ii regions but rather reflects a sequence with different initial gas densities (or “hierarchy” of density). We also find that the dust extinction of ionizing photons is significant for the BCD sample, despite their blue optical colors. This means that as long as the emission from H ii regions is used to trace massive star formation, we would miss the star formation activity in dense environments even in low-metallicity galaxies such as BCDs.

scholarly journals The hierarchical evolution of Brightest Cluster Galaxies: red galaxies in a young universe

2012 ◽  
Vol 8 (S295) ◽  
pp. 200-203
Author(s):  
Chiara Tonini
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Star Formation History ◽  
Analytic Model ◽  
Cluster Galaxies ◽  
Star Formation Activity ◽  
Brightest Cluster Galaxies ◽  
Formation History ◽  
Red Galaxies ◽  
Analytic Models

AbstractWe investigate the evolution of Brightest Cluster Galaxies (BCGs) from redshift z ~ 1.6 to z = 0. We upgrade the hierarchical semi-analytic model of Croton et al. (2006) with a new spectro-photometric model that produces realistic galaxy spectra, making use of the Maraston (2005) stellar populations and a new recipe for the dust extinction. We compare the model predictions of the K-band luminosity evolution and the J-K, V-I and I-K colour evolution with a series of datasets, including Collins et al. (Nature, 2009) who argued that semi-analytic models based on the Millennium simulation cannot reproduce the red colours and high luminosity of BCGs at z > 1. We show instead that the model is well in range of the observed luminosity and correctly reproduces the colour evolution of BCGs in the whole redshift range up to z ~ 1.6. We argue that the success of the semi-analytic model is in large part due to the implementation of a more sophisticated spectro-photometric model. An analysis of the model BCGs shows an increase in mass by a factor 2-3 since z ~ 1, and star formation activity down to low redshifts. While the consensus regarding BCGs is that they are passively evolving, we argue that this conclusion is affected by the degeneracy between star formation history and stellar population models used in SED-fitting, and by the inefficacy of toy-models of passive evolution to capture the complexity of real galaxies, especially those with rich merger histories like BCGs. Following this argument, we also show that in the semi-analytic model, the BCGs show a realistic mix of stellar populations, and that these stellar populations are mostly old. In addition, the age-redshift relation of the model BCGs follows that of the Universe, meaning that given their merger history and star formation history, the ageing of BCGs is always dominated by the ageing of their stellar populations. In a ΛCDM Universe, we define such evolution as ‘passive in the hierarchical sense’.

scholarly journals Dynamical and Chemical Evolution of IZw18

2004 ◽  
Vol 21 (2) ◽  
pp. 157-160
Author(s):  
Simone Recchi
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Intermediate Mass ◽  
Intermediate Mass Stars ◽  
Formation History ◽  
Type Ia ◽  
Ia Supernovae ◽  
Detailed Chemical

AbstractWe study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.

scholarly journals STAR FORMATION HISTORY AND CHEMICAL EVOLUTION OF THE SEXTANS DWARF SPHEROIDAL GALAXY

2009 ◽  
Vol 703 (1) ◽  
pp. 692-701 ◽  
Author(s):  
Myung Gyoon Lee ◽  
In-Soo Yuk ◽  
Hong Soo Park ◽  
Jason Harris ◽  
Dennis Zaritsky
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Star Formation History ◽  
Formation History

scholarly journals The LMC Centre Unfolding

1999 ◽  
Vol 190 ◽  
pp. 357-358 ◽  
Author(s):  
A. Ardeberg ◽  
P. Linde ◽  
B. Gustafsson
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Star Formation History ◽  
Formation History

We study star formation history and chemical evolution in the LMC Bar centre. With the HST PC and WFC plus uvby photometry, we find 30% of the stars younger than 200 My and evidence for reduced star formation 3 to 0.2 Gy ago. The overall [Fe/H] is −0.5. Many stars older than 4 Gy contradict a very young Bar.

scholarly journals A Comparison of Chemical Evolution between the Milky Way and M31 Galaxy

2006 ◽  
Vol 2 (S235) ◽  
pp. 313-313
Author(s):  
J. Yin ◽  
J.L. Hou ◽  
R.X. Chang ◽  
S. Boissier ◽  
N. Prantzos
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Milky Way ◽  
Local Group ◽  
Spiral Galaxies ◽  
Star Formation History ◽  
Milky Way Galaxy ◽  
Andromeda Galaxy ◽  
Formation History ◽  
Formation And Evolution

Andromeda galaxy (M31,NGC224) is the biggest spiral in the Local Group. By studying the star formation history(SFH) and chemical evolution of M31, and comparing with the Milky Way Galaxy, we are able to understand more about the formation and evolution of spiral galaxies.

scholarly journals SMART for the Next Decade

2009 ◽  
Vol 5 (S262) ◽  
pp. 291-294
Author(s):  
Myung Gyoon Lee ◽  
In-Soo Yuk ◽  
Sungsoon Lim
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Star Formation History ◽  
Formation History

AbstractSMART is a model to derive both star formation history and chemical evolution simultaneously from color-magnitude diagrams of resolved stars in a galaxy. We present current progress and discuss the prospects of SMART for the next decade.

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?

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