%0 Generic %1 ocvirk2021lymanalpha %A Ocvirk, Pierre %A Lewis, Joseph S. W. %A Gillet, Nicolas %A Chardin, Jonathan %A Aubert, Dominique %A Deparis, Nicolas %A Thelie, Emilie %D 2021 %K library %T Lyman-alpha opacities at z=4-6 require low mass, radiatively-suppressed galaxies to drive cosmic reionization %U http://arxiv.org/abs/2105.01663 %X The high redshift Lyman-alpha forest, in particular the Gunn-Peterson trough, is the most unambiguous signature of the neutral to ionized transition of the intergalactic medium (IGM) taking place during the Epoch of Reionization (EoR). Recent studies, e.g. Kulkarni et al. (2019a) and Keating et al. (2019), showed that reproducing the observed Lyman-alpha opacities after overlap required a non-monotonous evolution of cosmic emissivity: rising, peaking at z=6, and then decreasing onwards to z=4. Such an evolution is puzzling considering galaxy build-up and the cosmic star formation rate are still continously on the rise at these epochs. Here, we use new RAMSES-CUDATON simulations to show that such a peaked evolution may occur naturally in a fully coupled radiation-hydrodynamical framework, due to radiative suppression of star formation. In our best matching run, cosmic emissivity at z>6 is dominated by a low mass (M$_DM<2.10^9$ M$_ødot$), high escape fraction halo population, driving reionization, up to overlap. Approaching z=6, this population is radiatively suppressed due to the rising ionizing UV background, and its emissivity drops.In the meantime, the high mass, low escape fraction, halo population builds up and its emissivity rises, but not fast enough to compensate the dimming of the low mass haloes. The combined ionizing emissivity of these two populations therefore naturallyresults in a rise and fall of the cosmic emissivity, from z=12 to z=4, with a peak at z=6. An alternative simulation, which features a later suppression and higher escape fractions for the high mass haloes, leads to overshooting the ionizing rate, over-ionizing the IGM and therefore too low Lyman-alpha opacities.

@misc{ocvirk2021lymanalpha, abstract = {The high redshift Lyman-alpha forest, in particular the Gunn-Peterson trough, is the most unambiguous signature of the neutral to ionized transition of the intergalactic medium (IGM) taking place during the Epoch of Reionization (EoR). Recent studies, e.g. Kulkarni et al. (2019a) and Keating et al. (2019), showed that reproducing the observed Lyman-alpha opacities after overlap required a non-monotonous evolution of cosmic emissivity: rising, peaking at z=6, and then decreasing onwards to z=4. Such an evolution is puzzling considering galaxy build-up and the cosmic star formation rate are still continously on the rise at these epochs. Here, we use new RAMSES-CUDATON simulations to show that such a peaked evolution may occur naturally in a fully coupled radiation-hydrodynamical framework, due to radiative suppression of star formation. In our best matching run, cosmic emissivity at z>6 is dominated by a low mass (M$_{\rm DM}<2.10^9$ M$_{\odot}$), high escape fraction halo population, driving reionization, up to overlap. Approaching z=6, this population is radiatively suppressed due to the rising ionizing UV background, and its emissivity drops.In the meantime, the high mass, low escape fraction, halo population builds up and its emissivity rises, but not fast enough to compensate the dimming of the low mass haloes. The combined ionizing emissivity of these two populations therefore naturallyresults in a rise and fall of the cosmic emissivity, from z=12 to z=4, with a peak at z=6. An alternative simulation, which features a later suppression and higher escape fractions for the high mass haloes, leads to overshooting the ionizing rate, over-ionizing the IGM and therefore too low Lyman-alpha opacities.}, added-at = {2021-05-06T05:55:05.000+0200}, author = {Ocvirk, Pierre and Lewis, Joseph S. W. and Gillet, Nicolas and Chardin, Jonathan and Aubert, Dominique and Deparis, Nicolas and Thelie, Emilie}, biburl = {https://www.bibsonomy.org/bibtex/2595648ae2788e450fe4c7c95f128eb4b/gpkulkarni}, description = {Lyman-alpha opacities at z=4-6 require low mass, radiatively-suppressed galaxies to drive cosmic reionization}, interhash = {0d57956b01fe8be8fa6ad95e30390da1}, intrahash = {595648ae2788e450fe4c7c95f128eb4b}, keywords = {library}, note = {cite arxiv:2105.01663Comment: 9 pages, 6 figures, subbmitted to MNRAS}, timestamp = {2021-05-06T05:55:05.000+0200}, title = {Lyman-alpha opacities at z=4-6 require low mass, radiatively-suppressed galaxies to drive cosmic reionization}, url = {http://arxiv.org/abs/2105.01663}, year = 2021 }