Impact of Ly$\alpha$ heating on the global 21-cm signal from the Cosmic Dawn

Abstract

The resonance scattering of Ly$\alpha$ photons with neutral hydrogen atoms in the intergalactic medium 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 of a strong absorption signal at $z\approx 17$ 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. We also show that the cooling mechanism driven by the interaction between millicharged baryons and dark matter particles no longer provides a viable explanation for the EDGES result when Ly$\alpha$ heating is taken into account.

11 Pages, 6 Figures, 2 Tables, Accepted for publication in MNRAS

References in corpus (13)

• 21 cm fluctuations from inhomogeneous X-ray heating before reionization
• Signature of Excess Radio Background in the 21-cm Global Signal and Power Spectrum
• BIGHORNS - Broadband Instrument for Global HydrOgen ReioNisation Signal
• 21 cm signal from cosmic dawn: Imprints of spin temperature fluctuations and peculiar velocities
• Characterizing Foreground for redshifted 21-cm radiation: 150 MHz GMRT observations
• Cosmic Reionization and the 21-cm signal: Comparison between an analytical model and a simulation
• The Scattering of Lyman-series Photons in the Intergalactic Medium
• Results from EDGES High-Band: III. New Constraints on Parameters of the Early Universe
• Imaging the redshifted 21-cm pattern around the first sources during the cosmic dawn using the SKA
• Heating and cooling of the intergalactic medium by resonance photons
• SARAS measurement of the Radio Background at long wavelengths
• Fuzzy Dark Matter at Cosmic Dawn: New 21-cm Constraints
• Cosmological implications of the composite spectra of galactic X-ray binaries constructed using MAXI data

Cited by in corpus (30)

• Tight Constraints on the Excess Radio Background at $z=9.1$ from LOFAR
• High-redshift radio galaxies: a potential new source of 21-cm fluctuations
• The subtlety of Ly-a photons: changing the expected range of the 21-cm signal
• Constraining the state of the intergalactic medium during the Epoch of Reionization using MWA 21-cm signal observations
• Lyman-$\alpha$ coupling and heating at Cosmic Dawn
• Redshifted 21-cm bispectrum II: Impact of the spin temperature fluctuations and redshift space distortions on the signal from the Cosmic Dawn
• Prospects of constraining reionization model parameters using Minkowski tensors and Betti numbers
• CosmoReionMC: A package for estimating cosmological and astrophysical parameters using CMB, Lyman-α absorption and global 21 cm data
• Cosmic Reionization May Still Have Started Early and Ended Late: Confronting Early Onset with CMB Anisotropy and 21 cm Global Signals
• Studying Cosmic Dawn using redshifted HI 21-cm signal: A brief review
• Constraining spinning primordial black holes with global 21-cm signal
• Constraint on Primordial Magnetic Fields In the Light of ARCADE 2 and EDGES Observations
• The role of Pop III stars and early black holes in the 21cm signal from Cosmic Dawn
• Baryon-Dark matter interaction in presence of magnetic fields in light of EDGES signal
• A Model-Insensitive Baryon Acoustic Oscillation Feature in the 21 cm Signal from Reionization
• Primordial magnetic fields during the cosmic dawn in light of EDGES 21-cm signal
• Constraints on the state of the IGM at $z\sim 8-10$ using redshifted 21-cm observations with LOFAR
• Bayesian approach to constraining the properties of ionized bubbles during reionization
• EDGES signal in presence of magnetic fields
• Astrophysical information from the Rayleigh-Jeans Tail of the CMB
• 21cmFirstCLASS II. Early linear fluctuations of the 21cm signal
• Probing the intergalactic medium during the Epoch of Reionization using 21-cm signal power spectra
• The impact of Lyman-$\alpha$ emission line heating and cooling on the cosmic dawn 21-cm signal
• Bounds on sterile neutrino lifetime and mixing angle with active neutrinos by global 21 cm signal
• Impact of cosmic rays on the global 21-cm signal during cosmic dawn
• Large HI optical depth and Redshifted 21-cm signal from cosmic dawn
• Global 21cm Absorption Signal from Superconducting Cosmic Strings
• Constraining the Hubble parameter with the 21 cm brightness temperature signal in a universe with inhomogeneities
• 21 cm Signal from the Thermal Evolution of Lyman-$\alpha$ during Cosmic Dawn
• Thermal Evolution of the IGM due to Lyman-α photons during the Cosmic Dawn