SMBH Seeds from Dissipative Dark Matter
  The existence of supermassive black holes (SMBHs) with masses greater than
$\sim 10^{9}M_{\odot}$ at high redshift ($z\gtrsim 7$) is difficult to
accommodate in standard astrophysical scenarios. We study the possibility that
(nearly) totally dissipative self-interacting dark matter (tdSIDM)--in rare,
high density dark matter fluctuations in the early Universe--produces SMBH
seeds through catastrophic collapse. We use a semi-analytic model, tested and
calibrated by a series of N-body simulations of isolated dark matter halos, to
compute the collapse criteria and timescale of tdSIDM halos, where dark matter
loses nearly all of its kinetic energy in a single collision in the
center-of-momentum frame. Applying this model to halo merger trees, we
empirically assign SMBH seeds to halos and trace the formation and evolution
history of SMBHs. We make predictions for the quasar luminosity function, the
$M_{\rm BH}$-$\sigma_{\rm v}^{\ast}$ relation, and cosmic SMBH mass density at
high redshift and compare them to observations. We find that a dissipative dark
matter interaction cross-section of $\sigma/m \sim 0.05~\rm cm^2/g$ is
sufficient to produce the SMBHs observed in the early Universe while remaining
consistent with ordinary SMBHs in the late Universe.
