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Ultra-Compact High Velocity Clouds as Minihalos and Dwarf Galaxies by Faerman, Yakov; Sternberg, Amiel; McKee, Christopher F. is a scholarly article available to read on EtoBox.

What is Ultra-Compact High Velocity Clouds as Minihalos and Dwarf Galaxies about?

We present dark-matter minihalo models for the Ultra-Compact High Velocity HI Clouds (UCHVCs) recently discovered in the 21 cm ALFALFA survey. We assume gravitational confinement of 10^4 K HI gas by flat-cored dark-matter subhalos within the Local Group. We show that for flat cores, typical (median) tidally-stripped cosmological subhalos at redshift z=0 have dark-matter masses of ~10^7 M_{sun} within the central 300 pc (independent of total halo mass), consistent with the "Strigari mass scale" observed in low-luminosity dwarf galaxies. Flat-cored subhalos also resolve the mass-discrepancy between simulated and observed satellites around the Milky Way. For the UCHVCs we calculate the photoionization-limited hydrostatic gas profiles for any distance-dependent total observed HI mass and predict the associated (projected) HI half-mass radii, assuming the clouds are embedded in distant (d > 300 kpc) and unstripped subhalos. For a typical UCHVC (0.9 Jy km/s) we predict physical HI half-mass radii of 0.18 to 0.35 kpc (or angular sizes of 0.6 to 2.1 arcmin) for distances ranging from 300 kpc to 2 Mpc. As a consistency check we model the gas rich dwarf galaxy Leo T, for which there is a wel

Author

Faerman, Yakov; Sternberg, Amiel; McKee, Christopher F.

Published

2013

Language

EN