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

Saurabh Singh; Ravi Subrahmanyan; N. Udaya Shankar; Mayuri Sathyanarayana Rao; Anastasia Fialkov; Aviad Cohen; Rennan Barkana; B. S. Girish; A. Raghunathan; R. Somashekar; K. S. Srivani

doi:https://doi.org/10.3847/2041-8213/aa831b

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

Saurabh Singh, Ravi Subrahmanyan, N. Udaya Shankar, Mayuri Sathyanarayana Rao, Anastasia Fialkov, Aviad Cohen, Rennan Barkana, B. S. Girish, A. Raghunathan, R. Somashekar, K. S. Srivani

School of Physics and Astronomy

Tel Aviv University

Research output: Contribution to journal › Article › peer-review

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. SARAS2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63hr nighttime observations of the radio background in the frequency band 110-200MHz, 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 fX ≤ 0.1) and rapid reionization (with peak dT_b/dzb ≥ 120 mK per unit redshift interval).

Original language	English
Article number	L12
Journal	Astrophysical Journal Letters
Volume	845
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/aa831b
State	Published - 20 Aug 2017

Keywords

cosmic background radiation
cosmology: observations
dark ages
first stars-methods: observational
reionization

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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https://doi.org/10.3847/2041-8213/aa831b

Cite this

@article{4905419c72f34d6b9de09785b76110bd,

title = "First Results on the Epoch of Reionization from First Light with SARAS 2",

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. SARAS2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63hr nighttime observations of the radio background in the frequency band 110-200MHz, 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 fX ≤ 0.1) and rapid reionization (with peak dTb/dzb ≥ 120 mK per unit redshift interval).",

keywords = "cosmic background radiation, cosmology: observations, dark ages, first stars-methods: observational, reionization",

author = "Saurabh Singh and Ravi Subrahmanyan and Shankar, {N. Udaya} and Rao, {Mayuri Sathyanarayana} and Anastasia Fialkov and Aviad Cohen and Rennan Barkana and Girish, {B. S.} and A. Raghunathan and R. Somashekar and Srivani, {K. S.}",

note = "Funding Information: We thank the anonymous referee for valuable comments that led to improved methods of data analysis. We thank the staff at Gauribidanur Field Station for assistance with system tests and measurements, and the Mechanical and Electronics Engineering Groups at Raman Research Institute for building and assembling SARAS2. Santosh Harish and Divya Jayasankar implemented real-time software and monitoring. Logistics and technical support for observations was provided by Indian Astronomical Observatory, Leh operated by Indian Institute of Astrophysics, and Timbaktu Collective, India. For R.B. and A. C. this project/publication was made possible through the support of a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of the John Templeton Foundation.",

year = "2017",

month = aug,

day = "20",

doi = "https://doi.org/10.3847/2041-8213/aa831b",

language = "الإنجليزيّة",

volume = "845",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "IOP Publishing Ltd.",

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T1 - First Results on the Epoch of Reionization from First Light with SARAS 2

AU - Singh, Saurabh

AU - Subrahmanyan, Ravi

AU - Shankar, N. Udaya

AU - Rao, Mayuri Sathyanarayana

AU - Fialkov, Anastasia

AU - Cohen, Aviad

AU - Barkana, Rennan

AU - Girish, B. S.

AU - Raghunathan, A.

AU - Somashekar, R.

AU - Srivani, K. S.

N1 - Funding Information: We thank the anonymous referee for valuable comments that led to improved methods of data analysis. We thank the staff at Gauribidanur Field Station for assistance with system tests and measurements, and the Mechanical and Electronics Engineering Groups at Raman Research Institute for building and assembling SARAS2. Santosh Harish and Divya Jayasankar implemented real-time software and monitoring. Logistics and technical support for observations was provided by Indian Astronomical Observatory, Leh operated by Indian Institute of Astrophysics, and Timbaktu Collective, India. For R.B. and A. C. this project/publication was made possible through the support of a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of the John Templeton Foundation.

PY - 2017/8/20

Y1 - 2017/8/20

N2 - 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. SARAS2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63hr nighttime observations of the radio background in the frequency band 110-200MHz, 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 fX ≤ 0.1) and rapid reionization (with peak dTb/dzb ≥ 120 mK per unit redshift interval).

AB - 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. SARAS2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63hr nighttime observations of the radio background in the frequency band 110-200MHz, 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 fX ≤ 0.1) and rapid reionization (with peak dTb/dzb ≥ 120 mK per unit redshift interval).

KW - cosmic background radiation

KW - cosmology: observations

KW - dark ages

KW - first stars-methods: observational

KW - reionization

UR - http://www.scopus.com/inward/record.url?scp=85028468301&partnerID=8YFLogxK

U2 - https://doi.org/10.3847/2041-8213/aa831b

DO - https://doi.org/10.3847/2041-8213/aa831b

M3 - مقالة

SN - 2041-8205

VL - 845

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L12

ER -

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

Abstract

Keywords

All Science Journal Classification (ASJC) codes

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