Impact of inhomogeneous reionization on the Lyman-{alpha} forest. (arXiv:1902.02892v1 [astro-ph.CO])

Impact of inhomogeneous reionization on the Lyman-{alpha} forest. (arXiv:1902.02892v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Montero_Camacho_P/0/1/0/all/0/1">Paulo Montero-Camacho</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirata_C/0/1/0/all/0/1">Christopher M. Hirata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martini_P/0/1/0/all/0/1">Paul Martini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Honscheid_K/0/1/0/all/0/1">Klaus Honscheid</a>

The Lyman-${alpha}$ forest at high redshifts is a powerful probe of
reionization. Modeling and observing this imprint comes with significant
technical challenges: the memory fades away swiftly, hence one must focus on
high redshifts. In addition, inhomogeneous reionization must be taken into
account while simultaneously being able to resolve the web-like small-scale
structure, which has gone fully non-linear prior to reionization. Here we use
both small box simulations capable of handling the small-scale structure of the
Lyman-${alpha}$ forest and semi-numerical large box simulations capable of
representing the effects of inhomogeneous reionization. We find that
inhomogeneous reionization could produce a measurable effect on the
Lyman-${alpha}$ forest power spectrum. The deviation in the 3D power spectrum
at $z_{rm obs} = 4$ and $k = 0.14$ Mpc$^{-1}$ ranges from $19 – 36%$, with a
larger effect for later reionization. The corrections decrease to $2.0 – 4.1%$
by $z_{rm obs} = 2$. The impact on the 1D power spectrum is smaller, and
ranges from $3.3 – 6.5%$ at $z_{rm obs} = 4 $ to $ 0.35 – 0.75%$ at $z_{rm
obs} = 2$, values which are comparable to the statistical uncertainties in
current and upcoming surveys. Furthermore, we study how can this systematic be
constrained with the help of the quadrupole of the 21 cm power spectrum.

The Lyman-${alpha}$ forest at high redshifts is a powerful probe of
reionization. Modeling and observing this imprint comes with significant
technical challenges: the memory fades away swiftly, hence one must focus on
high redshifts. In addition, inhomogeneous reionization must be taken into
account while simultaneously being able to resolve the web-like small-scale
structure, which has gone fully non-linear prior to reionization. Here we use
both small box simulations capable of handling the small-scale structure of the
Lyman-${alpha}$ forest and semi-numerical large box simulations capable of
representing the effects of inhomogeneous reionization. We find that
inhomogeneous reionization could produce a measurable effect on the
Lyman-${alpha}$ forest power spectrum. The deviation in the 3D power spectrum
at $z_{rm obs} = 4$ and $k = 0.14$ Mpc$^{-1}$ ranges from $19 – 36%$, with a
larger effect for later reionization. The corrections decrease to $2.0 – 4.1%$
by $z_{rm obs} = 2$. The impact on the 1D power spectrum is smaller, and
ranges from $3.3 – 6.5%$ at $z_{rm obs} = 4 $ to $ 0.35 – 0.75%$ at $z_{rm
obs} = 2$, values which are comparable to the statistical uncertainties in
current and upcoming surveys. Furthermore, we study how can this systematic be
constrained with the help of the quadrupole of the 21 cm power spectrum.

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