The Signatures of Large-scale Temperature and Intensity Fluctuations in
  the Lyman-alpha Forest
  It appears inevitable that reionization processes would have produced
large-scale temperature fluctuations in the intergalactic medium. Using toy
temperature models and detailed heating histories from cosmological simulations
of HeII reionization, we study the consequences of inhomogeneous heating for
the Ly-alpha forest. The impact of temperature fluctuations in physically
well-motivated models can be surprisingly subtle. In fact, we show that
temperature fluctuations at the level predicted by our reionization simulations
do not give rise to detectable signatures in the types of statistics that have
been employed previously. However, because of the aliasing of small-scale
density power to larger scale modes in the line-of-sight Ly-alpha forest power
spectrum, earlier analyses were not sensitive to 3D modes with >~ 30 comoving
Mpc wavelengths -- scales where temperature fluctuations are likely to be
relatively largest. The ongoing Baryon Oscillation Spectroscopic Survey (BOSS)
aims to measure the 3D power spectrum of the Ly-alpha forest, P_F, from a large
sample of quasars in order to avoid this aliasing. We find that physically
motivated temperature models can alter P_F at an order unity level at k <~ 0.1
comoving Mpc^{-1}, a magnitude that should be easily detectable with BOSS.
Fluctuations in the intensity of the ultraviolet background can also alter P_F
significantly. These signatures will make it possible for BOSS to study the
thermal impact of HeII reionization at 2 < z < 3 and to constrain models for
the sources of the ionizing background. Future spectroscopic surveys could
extend this measurement to even higher redshifts, potentially detecting the
thermal imprint of hydrogen reionization.
