ON THE ASSEMBLY OF THE MILKY WAY DWARF SATELLITES AND THEIR COMMON MASS SCALE
- Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
- Theoretical Astrophysics Center, University of California Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States)
- Institute of Theoretical Physics, University of Zuerich, Winterhurerstrasse 190, CH-8057 Zuerich (Switzerland)
We use a particle tagging technique to dynamically populate the N-body Via Lactea II high-resolution simulation with stars. The method is calibrated using the observed luminosity function of Milky Way (MW) satellites and the concentration of their stellar populations, and self-consistently follows the accretion and disruption of progenitor dwarfs and the buildup of the stellar halo in a cosmological 'live host'. Simple prescriptions for assigning stellar populations to collisionless particles are able to reproduce many properties of the observed MW halo and its surviving dwarf satellites, like velocity dispersions, sizes, brightness profiles, metallicities, and spatial distribution. Our model predicts the existence of approximately 1850 subhalos harboring 'extremely faint' satellites (with mass-to-light ratios >5 Multiplication-Sign 10{sup 3}) lying beyond the Sloan Digital Sky Survey detection threshold. Of these, about 20 are 'first galaxies', i.e., satellites that formed a stellar mass above 10 M{sub Sun} before redshift 9. The 10 most luminous satellites (L > 10{sup 6} L{sub Sun }) in the simulation are hosted by subhalos with peak circular velocities today in the range V{sub max} = 10-40 km s{sup -1} that have shed between 80% and 99% of their dark mass after being accreted at redshifts 1.7 < z < 4.6. The satellite maximum circular velocity V{sub max} and stellar line-of-sight velocity dispersion {sigma}{sub los} today follow the relation V{sub max} = 2.2{sigma}{sub los}. We apply a standard mass estimation algorithm based on Jeans modeling of the line-of-sight velocity dispersion profiles to the simulated dwarf spheroidals and test the accuracy of this technique. The inner (within 300 pc) mass-luminosity relation for currently detectable satellites is nearly flat in our model, in qualitative agreement with the 'common mass scale' found in MW dwarfs. We do, however, predict a weak, but significant positive correlation for these objects: M{sub 300}{proportional_to}L {sup 0.088{+-}0.024}.
- OSTI ID:
- 22011899
- Journal Information:
- Astrophysical Journal, Vol. 745, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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