Abstract / Description of output
We calculate the energy that baryons must inject into cold dark matter
(CDM) halos in order to remove centrally divergent DM cusps on scales
relevant to observations of dwarf spheroidal galaxies (dSphs). We
estimate that the CDM halos often associated with the Milky Way's dSphs
(M vir/M ⊙ ~ 109-10) require
ΔE ~ 1053-55 erg in order to form cores on scales
comparable to the luminous size of these galaxies. While supernova Type
II (SNeII) explosions can in principle generate this energy, the actual
contribution is limited by the low star formation efficiency implied by
the abundance of luminous satellites. Considering that CDM's well-known
"core/cusp" and "missing satellite" problems place opposing demands on
star formation efficiencies, existing observational evidences for large
cores in the most luminous dSphs require that CDM models invoke some
combination of the following: (1) efficient (of the order of unity)
coupling of SNeII energy into dark matter particles, (2) star formation
histories peaking at unexpectedly high redshifts (z >~ 6), (3) a
top-heavy stellar initial mass function, and/or (4) substantial
satellite disruption or other stochastic effects to ease the
substructure abundance constraints. Our models show that the tension
between CDM problems on small scales would increase if cored DM profiles
were to be found in fainter dwarfs.
Original language | English |
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Journal | Astrophysical Journal Letters |
Volume | 759 |
Issue number | 2 |
DOIs | |
Publication status | Published - 26 Oct 2012 |
Keywords / Materials (for Non-textual outputs)
- dark matter
- galaxies: dwarf
- galaxies: formation
- galaxies: halos
- Local Group