scholarly journals Spatial segregation impact on star formation in nearby dwarf spheroidal galaxies

2021 ◽  
Vol 502 (2) ◽  
pp. 1623-1632
Author(s):  
L N Makarova ◽  
D I Makarov
Keyword(s):  
Comparative Analysis ◽  
Star Formation ◽  
Middle Ages ◽  
Local Group ◽  
Hubble Space Telescope ◽  
Spatial Segregation ◽  
Dwarf Spheroidal Galaxies ◽  
M 31 ◽  
Advanced Camera For Surveys ◽  
Star Formation Histories

ABSTRACT Using our Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) observations of the recently found isolated dwarf spheroidal (dSph) galaxies, we homogeneously measured their star formation histories (SFHs). We determined SF rate as a function of time, as well as age and metallicity of the stellar populations. All objects demonstrate complex SFH, with a significant portion of stars formed 10–13 Gyr ago. Nevertheless, stars of middle ages (1–8 Gyr) are presented. In order to understand how the SF parameters influence the evolution of dSphs, we also studied a sample of nearest dSphs in different environment: isolated (d < 2 Mpc); beyond the Local Group (LG) virial radius (but within the LG zero-velocity sphere); and the satellites of M 31 located within the virial zone (300 kpc). Using archival HST/ACS observations, we measured their SFHs. A comparative analysis of the parameters obtained allow us to distinguish a possible effect of the spatial segregation on the dSphs evolution scenario.

The spatial segregation impact on the star formation histories of nearby dwarf spheroidal galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 389-391
Author(s):  
Lidia Makarova ◽  
Dmitry Makarov
Keyword(s):  
Comparative Analysis ◽  
Star Formation ◽  
Middle Ages ◽  
Local Group ◽  
Stellar Populations ◽  
Spatial Segregation ◽  
Dwarf Spheroidal Galaxies ◽  
Zero Velocity ◽  
Star Formation Histories ◽  
Spheroidal Galaxies

AbstractUsing our HST/ACS observations of the recently found isolated dwarf spheroidal galaxies, we homogeneously measured their star formation histories (SFHs). We determined SF rate as a function of time, as well as age and metallicity of the stellar populations. All objects demonstrate complex SFH, with a significant portion of stars formed 10–13 Gyr ago. Nevertheless, stars of middle ages (1–8 Gyr) are presented. In order to understand how the SF parameters influence the evolution of dSphs, we also studied a sample of nearest dSphs in different environment: isolated (d < 2 Mpc); beyond the Local Group virial radius (but within the LG zero velocity sphere); and the satellites of M31 located within the virial zone (300 kpc). Using archival HST/ACS observations, we measured their SFHs. A comparative analysis of the parameters obtained give us a possibility to distinguish a possible effect of the spatial segregation on the dSphs evolution scenario.

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 Evolutionary Histories of Dwarf Galaxies in the Local Group

1999 ◽  
Vol 192 ◽  
pp. 17-38 ◽  
Author(s):  
Eva K. Grebel
Keyword(s):  
Star Formation ◽  
Common Property ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Absolute Magnitude ◽  
Morphological Type ◽  
Red Giants ◽  
Dwarf Spheroidal Galaxies ◽  
Central Surface ◽  
Star Formation Histories

The star formation histories of Local Group (LG) dwarf galaxies and more distant potential LG members are reviewed. Problems in defining the spatial extent of the LG and membership are briefly discussed. The morphological types found in the LG are presented, and it is suggested that we see continuous evolution from low-mass dwarf irregulars (dIrrs) to dwarf spheroidal galaxies (dSphs) in the LG.Star formation histories for LG dwarfs and nearby LG candidates are compiled using population boxes. No two dwarfs, irrespective of morphological type, show the same evolutionary history, and all vary widely in ages of their subpopulations and in their enrichment history. The lack of gas in dSphs and certain dwarf ellipticals (dEs) is puzzling, both with respect to their star formation histories and the expected mass loss from red giants, but a new photoionization scenario may reconcile these contradictions. Old populations, often spatially very extended, may be a common property of dwarf galaxies, though their fractions can be very small. Almost all types of dwarf galaxies studied in detail so far show spatial variations in ages and abundances such as radial age/metallicity gradients. The observed star formation histories impose constraints on merger and accretion scenarios.Properties of the Milky Way dwarf spheroidals are compared to the M31 dSphs and discussed in the framework of the ram pressure/tidal stripping scenario. It is demonstrated that the newly discovered LG dwarfs follow the same relationship for central surface brightness, mean metallicity, and absolute magnitude as the other LG dwarfs.

scholarly journals Star Formation History of the Dwarf Galaxies in the Centaurus A Group

2006 ◽  
Vol 2 (S235) ◽  
pp. 320-320
Author(s):  
L. Makarova ◽  
D. Makarov ◽  
A. Dolphin ◽  
I. Karachentsev ◽  
B. Tully ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Hubble Space Telescope ◽  
Star Formation History ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of ◽  
Advanced Camera For Surveys ◽  
Star Formation Histories ◽  
Centaurus A

We derive quantitative star formation histories (SFH) of the two dwarf spheroidal (KK 197 and ESO 269-066) and one dwarf irregular (ESO 381-018) galaxies in the nearby Centaurus A group. The data are part of our sample of about 50 nearby dwarf galaxies observed with the Advanced Camera for Surveys (ACS) at the Hubble Space Telescope (prog. 9771 & 10235, PI I.Karachentsev). Deep color-magnitude diagram (CMD) of KK 197 is shown in Fig.1.

scholarly journals Local group star formation in warm and self-interacting dark matter cosmologies

2020 ◽  
Vol 498 (1) ◽  
pp. 702-717 ◽  
Author(s):  
Mark R Lovell ◽  
Wojciech Hellwing ◽  
Aaron Ludlow ◽  
Jesús Zavala ◽  
Andrew Robertson ◽  
...  
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Local Group ◽  
Initial Density ◽  
Dark Matter Mass ◽  
Stellar Ages ◽  
Hydrodynamical Simulations ◽  
Star Formation Histories

ABSTRACT The nature of the dark matter can affect the collapse time of dark matter haloes, and can therefore be imprinted in observables such as the stellar population ages and star formation histories of dwarf galaxies. In this paper, we use high-resolution hydrodynamical simulations of Local Group-analogue (LG) volumes in cold dark matter (CDM), sterile neutrino warm dark matter (WDM) and self-interacting dark matter (SIDM) models with the eagle galaxy formation code to study how galaxy formation times change with dark matter model. We are able to identify the same haloes in different simulations, since they share the same initial density field phases. We find that the stellar mass of galaxies depends systematically on resolution, and can differ by as much as a factor of 2 in haloes of a given dark matter mass. The evolution of the stellar populations in SIDM is largely identical to that of CDM, but in WDM early star formation is instead suppressed. The time at which LG haloes can begin to form stars through atomic cooling is delayed by ∼200 Myr in WDM models compared to CDM. It will be necessary to measure stellar ages of old populations to a precision of better than 100 Myr, and to address degeneracies with the redshift of reionization – and potentially other baryonic processes – in order to use these observables to distinguish between dark matter models.

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 &lt; 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 &gt; 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.

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