scholarly journals THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. I.HUBBLE SPACE TELESCOPE/WIDE FIELD PLANETARY CAMERA 2 OBSERVATIONS

2014 ◽  
Vol 789 (2) ◽  
pp. 147 ◽  
Author(s):  
Daniel R. Weisz ◽  
Andrew E. Dolphin ◽  
Evan D. Skillman ◽  
Jon Holtzman ◽  
Karoline M. Gilbert ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Wide Field ◽  
Space Telescope ◽  
Star Formation Histories

scholarly journals Pushing back the limits: detailed properties of dwarf galaxies in a ΛCDM universe

2018 ◽  
Vol 616 ◽  
pp. A96 ◽  
Author(s):  
Yves Revaz ◽  
Pascale Jablonka
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Mass Scale ◽  
Dwarf Spheroidal Galaxies ◽  
The Galaxy ◽  
Dynamical Simulations ◽  
Ursa Minor ◽  
Stellar Properties ◽  
Star Formation Histories

We present the results of a set of high-resolution chemo-dynamical simulations of dwarf galaxies in a ΛCDM cosmology. Out of an original (3.4 Mpc/h)3 cosmological box, a sample of 27 systems are re-simulated from z = 70 to z = 0 using a zoom-in technique. Gas and stellar properties are confronted to the observations in the greatest details: in addition to the galaxy global properties, we investigated the model galaxy velocity dispersion profiles, half-light radii, star formation histories, stellar metallicity distributions, and [Mg/Fe] abundance ratios. The formation and sustainability of the metallicity gradients and kinematically distinct stellar populations are also tackled. We show how the properties of six Local Group dwarf galaxies, NGC 6622, Andromeda II, Sculptor, Sextans, Ursa Minor and Draco are reproduced, and how they pertain to three main galaxy build-up modes. Our results indicate that the interaction with a massive central galaxy could be needed for a handful of Local Group dwarf spheroidal galaxies only, the vast majority of the systems and their variety of star formation histories arising naturally from a ΛCDM framework. We find that models fitting well the local Group dwarf galaxies are embedded in dark haloes of mass between 5 × 108 to a few 109 M⊙, without any missing satellite problem. We confirm the failure of the abundance matching approach at the mass scale of dwarf galaxies. Some of the observed faint however gas-rich galaxies with residual star formation, such as Leo T and Leo P, remain challenging. They point out the need of a better understanding of the UV-background heating.

scholarly journals Be it therefore resolved: cosmological simulations of dwarf galaxies with 30 solar mass resolution

2019 ◽  
Vol 490 (3) ◽  
pp. 4447-4463 ◽  
Author(s):  
Coral Wheeler ◽  
Philip F Hopkins ◽  
Andrew B Pace ◽  
Shea Garrison-Kimmel ◽  
Michael Boylan-Kolchin ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Stellar Rotation ◽  
Solar Mass ◽  
Dynamical Mass ◽  
Low Mass ◽  
Star Formation Histories ◽  
First Time

ABSTRACT We study a suite of extremely high-resolution cosmological Feedback in Realistic Environments simulations of dwarf galaxies ($M_{\rm halo} \lesssim 10^{10}\rm \, M_{\odot }$), run to z = 0 with $30\, \mathrm{M}_{\odot }$ resolution, sufficient (for the first time) to resolve the internal structure of individual supernovae remnants within the cooling radius. Every halo with $M_{\rm halo} \gtrsim 10^{8.6}\, \mathrm{M}_{\odot }$ is populated by a resolved stellar galaxy, suggesting very low-mass dwarfs may be ubiquitous in the field. Our ultra-faint dwarfs (UFDs; $M_{\ast }\lt 10^{5}\, \mathrm{M}_{\odot }$) have their star formation (SF) truncated early (z ≳ 2), likely by reionization, while classical dwarfs ($M_{\ast }\gt 10^{5}\, \mathrm{M}_{\odot }$) continue forming stars to z < 0.5. The systems have bursty star formation histories, forming most of their stars in periods of elevated SF strongly clustered in both space and time. This allows our dwarf with M*/Mhalo > 10−4 to form a dark matter core ${\gt}200\rm \, pc$, while lower mass UFDs exhibit cusps down to ${\lesssim}100\rm \, pc$, as expected from energetic arguments. Our dwarfs with $M_{\ast }\gt 10^{4}\, \mathrm{M}_{\odot }$ have half-mass radii (R1/2) in agreement with Local Group (LG) dwarfs (dynamical mass versus R1/2 and stellar rotation also resemble observations). The lowest mass UFDs are below surface brightness limits of current surveys but are potentially visible in next-generation surveys (e.g. LSST). The stellar metallicities are lower than in LG dwarfs; this may reflect pre-enrichment of the LG by the massive hosts or Pop-III stars. Consistency with lower resolution studies implies that our simulations are numerically robust (for a given physical model).

Local Group Dwarf Galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 29-37
Author(s):  
Andrew A. Cole
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Cosmic Time ◽  
Star Formation History ◽  
Gas Content ◽  
Cosmological Context ◽  
Low Mass ◽  
Formation And Evolution ◽  
Star Formation Histories

AbstractLocal Group dwarf galaxies are a unique astrophysical laboratory because they are the only objects in which we can reliably and precisely characterize the star formation histories of low-mass galaxies going back to the epoch of reionization. There are of order 100 known galaxies less massive than the Small Magellanic Cloud within ~1 Megaparsec of the Milky Way, with a vide variety of star formation history, gas content, and mass to light ratios. In this overview the current understanding of the formation and evolution of low-mass galaxies across cosmic time will be presented, and the possibility of drawing links between the properties of individual systems and the broader Local Group and cosmological context will be discussed. Local Group dwarfs will remain a uniquely powerful testbed to constrain the properties of dark matter and to evaluate the performance of simulations for the foreseeable future.

scholarly journals Stars at Low Metallicity in Dwarf Galaxies

2008 ◽  
Vol 4 (S255) ◽  
pp. 310-317
Author(s):  
Eline Tolstoy ◽  
Giuseppina Battaglia ◽  
Andrew Cole
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Wide Field ◽  
Irregular Galaxy ◽  
First Stars ◽  
Field Spectroscopy ◽  
Low Metallicity

AbstractDwarf galaxies offer an opportunity to understand the properties of low metallicity star formation both today and at the earliest times at the epoch of the formation of the first stars. Here we concentrate on two galaxies in the Local Group: the dwarf irregular galaxy Leo A, which has been the recent target of deep HST/ACS imaging (Cole et al. 2007) and the Sculptor dwarf spheroidal, which has been the target of significant wide field spectroscopy with VLT/FLAMES (Battaglia 2007).

scholarly journals Stellar Abundances in Local Group Galaxies

2005 ◽  
Vol 13 ◽  
pp. 548-553 ◽  
Author(s):  
Eline Tolstoy ◽  
Kim Venn
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Small Systems ◽  
Individual Stars ◽  
Abundance Patterns ◽  
Star Formation Histories ◽  
Evolution With Time ◽  
Detailed Chemical

AbstractHere we describe some of our latest results from measuring detailed abundances in Local Group dwarf galaxies with the VLT. Combining spectroscopic abundances with Color-Magnitude diagrams allows the effective measurement of detailed chemical evolution with time in these galaxies. Although there are not yet significant numbers of individual stars observed in local group dwarf galaxies, the uniformity of the abundance patterns of the majority of stars in galaxies with very different star formation histories must hint at general properties of all star formation in these small systems.

scholarly journals Orbits versus Star Formation Histories: A Progress Report

1999 ◽  
Vol 192 ◽  
pp. 447-450 ◽  
Author(s):  
Eva K. Grebel ◽  
Tsafrir Kolatt ◽  
Wolfgang Brandner
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Statistical Approach ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Progress Report ◽  
Polar Plane ◽  
Preliminary Results ◽  
Star Formation Histories

Milky Way dwarf companions and satellites of distant spirals seem to show a preference for polar orbits. We suggest that five out of six M31 dwarf spheroidal companions as well as two dwarf irregulars may also be located near a polar plane.We briefly discuss preliminary results from a statistical approach to study correlations between star formation histories and orbits of Local Group dwarf galaxies, such as a possible correlation between star formation episodes and galaxy separations.

scholarly journals THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. II. SEARCHING FOR SIGNATURES OF REIONIZATION

2014 ◽  
Vol 789 (2) ◽  
pp. 148 ◽  
Author(s):  
Daniel R. Weisz ◽  
Andrew E. Dolphin ◽  
Evan D. Skillman ◽  
Jon Holtzman ◽  
Karoline M. Gilbert ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Star Formation Histories

scholarly journals The star formation histories of dwarf galaxies in Local Group cosmological simulations

2019 ◽  
Vol 485 (4) ◽  
pp. 5423-5437 ◽  
Author(s):  
Ruth Digby ◽  
Julio F Navarro ◽  
Azadeh Fattahi ◽  
Christine M Simpson ◽  
Kyle A Oman ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Cosmological Simulations ◽  
Star Formation Histories
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