Licia Verde (Rutgers)
"Abundance of dwarf galaxies and DM halo profiles from observed rotation curves"


We show that gas in a large fraction of low mass dark matter halos may form Toomre-stable disks, if angular momentum is conserved when the gas contracts. Such halos would be stable to star formation and therefore remain dark. This may potentially explain the discrepancy between the predicted and observed number of dwarf satellites in the Local Group, as well as the deviation between the predicted and the observed faint end slope of the luminosity function. We show that model fits to rotation curves are also consistent with this hypothesis. Disk parameters are obtained by performing a likelihood analysis on a large set of high-spatial resolution optical rotation curves of galaxies. Our adopted model comprises of an exponential disk embedded within a cold dark matter halo that we model either with a Navarro, Frenk & White profile or a pseudo-isothermal profile. We present the statistical distribution of the recovered disk parameters and we show that the disk parameters of these galaxies avoid regions in parameter space for which the halos would be Toomre stable (i.e. would be dark).

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