Thermal state of the intergalactic medium at $zsim2-4$. (arXiv:1910.13184v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Telikova_K/0/1/0/all/0/1">K. N. Telikova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shternin_P/0/1/0/all/0/1">P. S. Shternin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Balashev_S/0/1/0/all/0/1">S. A. Balashev</a>

We present a new method to infer parameters of the temperature-density
relation in the intergalactic medium in the post-reionization epoch at $zsim
2-4$. This method is based on the analysis of the Ly$alpha$ absorbers
distribution over column densities and Doppler parameters by the model joint
probability density function. This approach allows us to measure the power-law
index $gamma$ of the temperature-density relation and a certain combination of
the temperature at the mean density $T_0$ and hydrogen photoionization rate
$Gamma$. To estimate $T_0$ and $Gamma$ separately, we employ measurements of
the Ly$alpha$ forest effective opacity and the model gas probability density
function. We show that $gamma$ tends to be lower than 1.6 and reaches 1.3 at
redshift $sim3$. The inferred temperatures at the mean density are
$sim(2pm0.5)times10^4$ K in the studied redshift range. Both these estimates
favour HeII reionization at $zgtrsim3$. We find that the hydrogen
photoionization rate is $sim0.6times10^{-12}$ s$^{-1}$, which is consistent
with previous measurements.

We present a new method to infer parameters of the temperature-density
relation in the intergalactic medium in the post-reionization epoch at $zsim
2-4$. This method is based on the analysis of the Ly$alpha$ absorbers
distribution over column densities and Doppler parameters by the model joint
probability density function. This approach allows us to measure the power-law
index $gamma$ of the temperature-density relation and a certain combination of
the temperature at the mean density $T_0$ and hydrogen photoionization rate
$Gamma$. To estimate $T_0$ and $Gamma$ separately, we employ measurements of
the Ly$alpha$ forest effective opacity and the model gas probability density
function. We show that $gamma$ tends to be lower than 1.6 and reaches 1.3 at
redshift $sim3$. The inferred temperatures at the mean density are
$sim(2pm0.5)times10^4$ K in the studied redshift range. Both these estimates
favour HeII reionization at $zgtrsim3$. We find that the hydrogen
photoionization rate is $sim0.6times10^{-12}$ s$^{-1}$, which is consistent
with previous measurements.

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