%0 Generic %1 lee2020hyrec2 %A Lee, Nanoom %A Ali-Haïmoud, Yacine %D 2020 %K tifr %T HYREC-2: a highly accurate sub-millisecond recombination code %U http://arxiv.org/abs/2007.14114 %X We present the new recombination code HYREC-2, holding the same accuracy as the state-of-the-art codes HYREC and COSMOREC and, at the same time, surpassing the computational speed of the code RECFAST commonly used for CMB-anisotropy data analyses. HYREC-2 is based on an effective 4-level atom model, accounting exactly for the non-equilibrium of highly excited states of hydrogen, and very accurately for radiative transfer effects with a correction to the Lyman-$\alpha$ escape rate. The latter is computed with the original HYREC, and tabulated, as a function of temperature, along with its derivatives with respect to the relevant cosmological parameters. This enables the code to keep the same accuracy as the original HYREC over the full 99.7% confidence region of cosmological parameters currently allowed by Planck, while running in under one millisecond on a standard laptop. Our code leads to no noticeable bias in any cosmological parameters even in the case of an ideal cosmic-variance limited experiment up to $\ell$ = 5000. Beyond CMB anisotropy calculations, HYREC-2 will be a useful tool to compute various observables that depend on the recombination and thermal history, such as the recombination spectrum or the 21-cm signal.

@misc{lee2020hyrec2, abstract = {We present the new recombination code HYREC-2, holding the same accuracy as the state-of-the-art codes HYREC and COSMOREC and, at the same time, surpassing the computational speed of the code RECFAST commonly used for CMB-anisotropy data analyses. HYREC-2 is based on an effective 4-level atom model, accounting exactly for the non-equilibrium of highly excited states of hydrogen, and very accurately for radiative transfer effects with a correction to the Lyman-$\alpha$ escape rate. The latter is computed with the original HYREC, and tabulated, as a function of temperature, along with its derivatives with respect to the relevant cosmological parameters. This enables the code to keep the same accuracy as the original HYREC over the full 99.7% confidence region of cosmological parameters currently allowed by Planck, while running in under one millisecond on a standard laptop. Our code leads to no noticeable bias in any cosmological parameters even in the case of an ideal cosmic-variance limited experiment up to $\ell$ = 5000. Beyond CMB anisotropy calculations, HYREC-2 will be a useful tool to compute various observables that depend on the recombination and thermal history, such as the recombination spectrum or the 21-cm signal.}, added-at = {2020-07-29T07:00:48.000+0200}, author = {Lee, Nanoom and Ali-Haïmoud, Yacine}, biburl = {https://www.bibsonomy.org/bibtex/20e3c167d5247d92b84fb007322fc1b17/citekhatri}, description = {HYREC-2: a highly accurate sub-millisecond recombination code}, interhash = {0ba7827c0d4d558b9b117514bde68772}, intrahash = {0e3c167d5247d92b84fb007322fc1b17}, keywords = {tifr}, note = {cite arxiv:2007.14114Comment: 14pages, 7 Figures}, timestamp = {2020-07-29T07:00:48.000+0200}, title = {HYREC-2: a highly accurate sub-millisecond recombination code}, url = {http://arxiv.org/abs/2007.14114}, year = 2020 }