On the Detection of Supermassive Primordial Stars
  The collapse of supermassive primordial stars in hot, atomically-cooled halos
may have given birth to the first quasars at $z \sim$ 15 - 20. Recent numerical
simulations of these rapidly accreting stars reveal that they are cool, red
hypergiants shrouded by dense envelopes of pristine atomically-cooled gas at
6,000 - 8,000 K, with luminosities $L$ $\gtrsim$ 10$^{10}$ L$_{\odot}$. Could
such luminous but cool objects be detected as the first stage of quasar
formation in future near infrared (NIR) surveys? We have now calculated the
spectra of supermassive primordial stars in their birth envelopes with the
Cloudy code. We find that some of these stars will be visible to JWST at $z
\lesssim$ 20 and that with modest gravitational lensing Euclid and WFIRST could
detect them out to $z \sim$ 10 - 12. Rather than obscuring the star, its
accretion envelope enhances its visibility in the NIR today by reprocessing its
short-wavelength flux into photons that are just redward of the Lyman limit in
the rest frame of the star.
