The observable signature of late heating of the Universe during cosmic reionization

2014/02/04 by Anastasia Fialkov, Rennan Barkana, Eli Visbal · 10 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #COSMIC cancer database #Cosmic background radiation #Cosmic microwave background #Cosmic ray #Dark Ages #Galaxies: Formation, Evolution, Phenomena #Galaxy #Ion #Ionization #Optics #Photon #Physics #Radio Astronomy Observations and Technology #Redshift #Reionization #Spectral line #Universe #astro-ph.CO

paper · pdf · doi:10.1038/nature12999

25 pages, 5 figures, published in Nature on Feb. 5, 2014 (online), Feb. 13 (print)

openalex publication_date 2014/02/04 · arxiv created 2014/02/05 · arxiv updated 2015/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

Models and simulations of the epoch of reionization predict that spectra of the 21-cm transition of atomic hydrogen will show a clear fluctuation peak, at a redshift and scale, respectively, that mark the central stage of reionization and the characteristic size of ionized bubbles. This is based on the assumption that the cosmic gas was heated by stellar remnants - particularly X-ray binaries - to temperatures well above the cosmic microwave background at that time (~ 30 K). Here we show instead that the hard spectra (that is, spectra with more high-energy photons than low-energy photons) of X-ray binaries make such heating ineffective, resulting in a delayed and spatially uniform heating that modifies the 21-cm signature of reionization. Rather than looking for a simple rise and fall of the large-scale fluctuations (peaking at several millikelvin), we must expect a more complex signal also featuring a distinct minimum (at less than a millikelvin) that marks the rise of the cosmic mean gas temperature above the microwave background. Observing this signal, possibly with radio telescopes in operation today, will demonstrate the presence of a cosmic background of hard X-rays at that early time.

Citations

• 21 Centimeter Tomography of the Intergalactic Medium at High Redshift
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Heating and Cooling of the Early Intergalactic Medium by Resonance Photons
• Large‐Scale Structure Shocks at Low and High Redshifts
• NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE ( WMAP ) OBSERVATIONS: FINAL MAPS AND RESULTS
• Relative velocity of dark matter and baryonic fluids and the formation of the first structures
• Simulations and Analytic Calculations of Bubble Growth during Hydrogen Reionization
• In the Beginning: The First Sources of Light and the Reionization of the Universe

Cited by

• Kiloparsec-scale turbulence driven by reionization may grow intergalactic magnetic fields
• PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM ATz= 8.4
• Charting the parameter space of the global 21-cm signal
• Reionization and Cosmic Dawn: theory and simulations
• Possible interaction between baryons and dark-matter particles revealed by the first stars
• The 21-cm BAO signature of enriched low-mass galaxies during cosmic reionization
• CHIPS: THE COSMOLOGICAL H i POWER SPECTRUM ESTIMATOR
• Design and characterization of the Large-aperture Experiment to Detect the Dark Age (LEDA) radiometer systems
• The Evolution Of 21 cm Structure (EOS): public, large-scale simulations of Cosmic Dawn and reionization
• Implications of the z > 5 Lyman-α forest for the 21-cm power spectrum from the epoch of reionization

Related

• Cosmic Reionization and the 21 cm Signal: Comparison between an Analytical Model and a Simulation
• Onset of Cosmic Reionization: Evidence of An Ionized Bubble Merely 680 Myrs after the Big Bang
• Unveiling the cosmic dawn and epoch of reionization using cosmic 21-cm signal
• HI Signatures of Reionization
• A New Boundary Condition on Reionization