期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 490, 期 3, 页码 4447-4463出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stz2887
关键词
galaxies: dwarf; galaxies: formation; galaxies: kinematics and dynamics; Local Group; galaxies: star formation
资金
- Lee A. DuBridge Postdoctoral Scholarship in Astrophysics
- Alfred P. Sloan Research Fellowship
- NSF [1715847, 1455342, AST-1517226, AST-1752913, AST-1517491, AST-1715216, AST-1652522]
- NASA [NNX15AT06G, JPL 1589742, 17-ATP17-0214, NNX17AG29G, 80NSSC18K1097, NNX15AB22G, 17-ATP17-0067, NAS8-03060, NAS5-26555, HEC SMD-16-7592]
- George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy at Texas AM University
- NASA through Einstein Postdoctoral Fellowship - Chandra X-ray Center [PF5-160136]
- Space Telescope Science Institute [HST-AR-13888, HST-AR-13896, HST-AR-14282, HST-AR-14554, HST-AR-15006, HST-GO-12914, HST-GO-14191]
- HST grants from STScI [GO-14734, AR-15057]
- Hellman Fellowship from UC Davis
- Cottrell Scholar Award from the Research Corporation for Science Advancement
We study a suite of extremely high-resolution cosmological Feedback in Realistic Environments simulations of dwarf galaxies (M-halo less than or similar to 10(10) M-circle dot), run to z = 0 with 30 M-circle dot resolution, sufficient (for the first time) to resolve the internal structure of individual supernovae remnants within the cooling radius. Every halo with M-halo greater than or similar to 108.6 M-circle dot is populated by a resolved stellar galaxy, suggesting very low-mass dwarfs may be ubiquitous in the field. Our ultra-faint dwarfs (UFDs; M-* < 10(5) M-circle dot) have their star formation (SF) truncated early (z greater than or similar to 2), likely by reionization, while classical dwarfs (M-* > 10(5) M-circle dot) 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-*/M-halo > 10(-4) to form a dark matter core >200 pc, while lower mass UFDs exhibit cusps down to less than or similar to 100 pc, as expected from energetic arguments. Our dwarfs with M-* > 10(4) M-circle dot have half-mass radii (R-1/2) in agreement with Local Group (LG) dwarfs (dynamical mass versus R-1/2 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).
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