First Results on the Epoch of Reionization from First Light with SARAS 2

Singh, Saurabh and Subrahmanyan, Ravi and Shankar, N. Udaya and Rao, Mayuri Sathyanarayana and Fialkov, Anastasia and Cohen, Aviad and Barkana, Rennan and Girish, B S and Raghunathan, A. and Somashekar, R and Srivani, K S (2017) First Results on the Epoch of Reionization from First Light with SARAS 2. In: ASTROPHYSICAL JOURNAL LETTERS, 845 (2).

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Abstract

Long-wavelength spectral distortions in the cosmic microwave background arising from the 21 cm transition in neutral hydrogen are a key probe of the Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first stars and ultra-faint galaxies that transformed the spin temperature and ionization state of the primordial gas. SARAS. 2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63. hr nighttime observations of the radio background in the frequency band 110-200. MHz, with the radiometer deployed at the Timbaktu Collective in Southern India, to derive likelihoods for plausible redshifted 21 cm signals predicted by theoretical models. First light with SARAS 2 disfavors the class of models that feature weak X-ray heating (with f(X) <= 0.1) and rapid reionization (with peak dT(b)/dz >= 120 mK per unit redshift interval).

Item Type:	Journal Article
Publication:	ASTROPHYSICAL JOURNAL LETTERS
Additional Information:	Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Department/Centre:	Division of Physical & Mathematical Sciences > Astronomy and Astrophysics Programme
Date Deposited:	09 Sep 2017 04:48
Last Modified:	09 Sep 2017 04:48
URI:	http://eprints.iisc.ac.in/id/eprint/57751

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