Bright vigorous winds as signposts of supermassive black hole birth
  The formation of supermassive black holes is still an outstanding question.
In the quasi-star scenario, black hole seeds experience an initial
super-Eddington growth, that in less than a million years may leave a
$10^4-10^5$ M$_{\odot}$ black hole at the centre of a protogalaxy at $z \sim
20-10$. Super-Eddington accretion, however, may be accompanied by vigorous mass
loss that can limit the amount of mass that reaches the black hole. In this
paper, we critically assess the impact of radiative driven winds, launched from
the surface of the massive envelopes from which the black hole accretes.
Solving the full wind equations coupled with the hydrostatic structure of the
envelope, we find mass outflows with rates between a few tens and $10^4$
M$_{\odot}$ yr$^{-1}$, mainly powered by advection luminosity within the
outflow. We therefore confirm the claim by Dotan, Rossi & Shaviv (2011) that
mass losses can severely affect the black hole seed early growth within a
quasi-star. In particular, seeds with mass $>10^4$ M$_{\odot}$ can only form
within mass reservoirs $ \gtrsim 10^7$ M$_{\odot}$, unless they are refilled at
huge rates ($ \gtrsim 100$ M$_{\odot}$ yr$^{-1}$). This may imply that only
very massive halos ($>10^9$ M$_{\odot}$) at those redshifts can harbour massive
seeds. Contrary to previous claims, these winds are expected to be relatively
bright ($10^{44}-10^{47}$ erg s$^{-1}$), blue ($T_{\rm eff} \sim 8000$ K)
objects, that while eluding the Hubble Space Telescope, could be observed by
the James Webb Space Telescope.
