%0 Generic %1 ghara2019impact %A Ghara, Raghunath %A Mellema, Garrelt %D 2019 %K library %T Impact of Ly$\alpha$ heating on the global 21-cm signal from the Cosmic Dawn %U http://arxiv.org/abs/1904.09999 %X The resonance scattering of Ly$\alpha$ photons with neutral hydrogen atoms in the IGM not only couples the spin temperature to the kinetic temperature but also leads to a heating of the gas. We investigate the impact of this heating on the average brightness temperature of the 21-cm signal from the Cosmic Dawn in the context of the claimed detection by the EDGES low-band experiment. We model the evolution of the global signal taking into account the Ly$\alpha$ coupling and heating and a cooling which can be stronger than the Hubble cooling. Using the claimed detection at $z17$ from the EDGES low-band observations as a constraint, we find that a strong Ly$\alpha$ background is ruled out. Instead the results favour a weak Ly$\alpha$ background combined with an excess cooling mechanism which is substantially stronger than previously considered.

@misc{ghara2019impact, abstract = {The resonance scattering of Ly$\alpha$ photons with neutral hydrogen atoms in the IGM not only couples the spin temperature to the kinetic temperature but also leads to a heating of the gas. We investigate the impact of this heating on the average brightness temperature of the 21-cm signal from the Cosmic Dawn in the context of the claimed detection by the EDGES low-band experiment. We model the evolution of the global signal taking into account the Ly$\alpha$ coupling and heating and a cooling which can be stronger than the Hubble cooling. Using the claimed detection at $z\approx 17$ from the EDGES low-band observations as a constraint, we find that a strong Ly$\alpha$ background is ruled out. Instead the results favour a weak Ly$\alpha$ background combined with an excess cooling mechanism which is substantially stronger than previously considered.}, added-at = {2019-04-24T04:58:35.000+0200}, author = {Ghara, Raghunath and Mellema, Garrelt}, biburl = {https://www.bibsonomy.org/bibtex/2336ffa77f63c484fea2b9479defb822e/gpkulkarni}, description = {Impact of Ly$\alpha$ heating on the global 21-cm signal from the Cosmic Dawn}, interhash = {8401884a476059e79dc17bae10fd1e0f}, intrahash = {336ffa77f63c484fea2b9479defb822e}, keywords = {library}, note = {cite arxiv:1904.09999Comment: 9 pages, 4 figures, submitted to MNRAS}, timestamp = {2019-04-24T04:58:35.000+0200}, title = {Impact of Ly$\alpha$ heating on the global 21-cm signal from the Cosmic Dawn}, url = {http://arxiv.org/abs/1904.09999}, year = 2019 }