Lyman-$\alpha$ Polarization Intensity Mapping

Understand

We present a formalism that incorporates hydrogen Lyman-alpha (Ly$\alpha$) polarization arising from the scattering of radiation in galaxy halos into the intensity mapping approach.

• Using the halo model, and emission profiles based on simulations and observations, we calculate auto and cross power spectra at redshifts $3\leq z \leq13$ for the Ly$\alpha$ total intensity, $I$, polarized intensity, $P$, degree of polarization, $\Pi=P/I$, and two new quantities, the astrophysical $E$ and $B$ modes of Ly$\alpha$ polarization.
• The one-halo terms of the $\Pi$ power spectra show a turnover that signals the average extent of the polarization signal, and thus the extent of the scattering medium.
• The position of this feature depends on redshift, and on the specific emission profile shape and extent, in our formalism.