On the spin-temperature evolution during the epoch of reionization

Rajat M. Thomas*, Saleem Zaroubi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

14 Citations (Scopus)
180 Downloads (Pure)

Abstract

Simulations estimating the brightness temperature (delta T-b) of the redshifted 21 cm from the epoch of reionization (EoR) often assume that the spin temperature (T-s) is decoupled from the background cosmic microwave background (CMB) temperature and is much larger than it, i.e. T-s T-CMB. Although a valid assumption towards the later stages of the reionization process, it does not necessarily hold at the earlier epochs. Violation of this assumption will lead to fluctuations in delta T-b that are driven neither by density fluctuations nor by H ii regions. Therefore, it is vital to calculate the spin temperature self-consistently by treating the Ly alpha and collisional coupling of T-s to the kinetic temperature, T-k. In this paper we develop an extension to the bears algorithm, originally developed to model reionization history, to include these coupling effects. Here, we simulate the effect in ionization and heating for three models in which the reionization is driven by stars, mini-QSOs or a mixture of both. We also perform a number of statistical tests to quantify the imprint of the self-consistent inclusion of the spin-temperature decoupling from the CMB. We find that the evolution of the spin temperature has an impact on the measured signal especially at redshifts higher than 10 and such evolution should be taken into account when one attempts to interpret the observational data.

Original languageEnglish
Pages (from-to)1377-1390
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume410
Issue number2
DOIs
Publication statusPublished - Jan-2011

Keywords

  • radiative transfer
  • methods: observational
  • cosmology: theory
  • diffuse radiation
  • radio lines: general
  • DIGITAL SKY SURVEY
  • COLD DARK-MATTER
  • 21 CM SIGNAL
  • ADAPTIVE MESH REFINEMENT
  • ALPHA RADIATIVE-TRANSFER
  • COSMOLOGICAL REIONIZATION
  • HYDROGEN REIONIZATION
  • INTERGALACTIC MEDIUM
  • BLACK-HOLES
  • 1ST STARS

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