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Title: INTERPRETING THE GLOBAL 21 cm SIGNAL FROM HIGH REDSHIFTS. I. MODEL-INDEPENDENT CONSTRAINTS

Abstract

The sky-averaged (global) 21 cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, so far it has been unclear whether it will provide more than crude estimates of when the universe's first stars and black holes formed, even in the best case scenario in which the signal is accurately extracted from the foregrounds. In contrast to previous work, which has focused on predicting the 21 cm signatures of the first luminous objects, we investigate an arbitrary realization of the signal and attempt to translate its features to the physical properties of the IGM. Within a simplified global framework, the 21 cm signal yields quantitative constraints on the Lyα background intensity, net heat deposition, ionized fraction, and their time derivatives without invoking models for the astrophysical sources themselves. The 21 cm absorption signal is most easily interpreted, setting strong limits on the heating rate density of the universe with a measurement of its redshift alone, independent of the ionization history or details of the Lyα background evolution. In a companion paper, we extend these results, focusing on the confidence with which one can infer source emissivities from IGM properties.

Authors:
;
Publication Date:
OSTI Identifier:
22270601
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 777; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASTROPHYSICS; BLACK HOLES; EMISSIVITY; HYDROGEN 1; INTERGALACTIC SPACE; LIMITING VALUES; LYMAN LINES; RED SHIFT; SIGNALS; STARS; UNIVERSE

Citation Formats

Mirocha, Jordan, Harker, Geraint J. A., and Burns, Jack O., E-mail: jordan.mirocha@colorado.edu. INTERPRETING THE GLOBAL 21 cm SIGNAL FROM HIGH REDSHIFTS. I. MODEL-INDEPENDENT CONSTRAINTS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/777/2/118.
Mirocha, Jordan, Harker, Geraint J. A., & Burns, Jack O., E-mail: jordan.mirocha@colorado.edu. INTERPRETING THE GLOBAL 21 cm SIGNAL FROM HIGH REDSHIFTS. I. MODEL-INDEPENDENT CONSTRAINTS. United States. https://doi.org/10.1088/0004-637X/777/2/118
Mirocha, Jordan, Harker, Geraint J. A., and Burns, Jack O., E-mail: jordan.mirocha@colorado.edu. Sun . "INTERPRETING THE GLOBAL 21 cm SIGNAL FROM HIGH REDSHIFTS. I. MODEL-INDEPENDENT CONSTRAINTS". United States. https://doi.org/10.1088/0004-637X/777/2/118.
@article{osti_22270601,
title = {INTERPRETING THE GLOBAL 21 cm SIGNAL FROM HIGH REDSHIFTS. I. MODEL-INDEPENDENT CONSTRAINTS},
author = {Mirocha, Jordan and Harker, Geraint J. A. and Burns, Jack O., E-mail: jordan.mirocha@colorado.edu},
abstractNote = {The sky-averaged (global) 21 cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, so far it has been unclear whether it will provide more than crude estimates of when the universe's first stars and black holes formed, even in the best case scenario in which the signal is accurately extracted from the foregrounds. In contrast to previous work, which has focused on predicting the 21 cm signatures of the first luminous objects, we investigate an arbitrary realization of the signal and attempt to translate its features to the physical properties of the IGM. Within a simplified global framework, the 21 cm signal yields quantitative constraints on the Lyα background intensity, net heat deposition, ionized fraction, and their time derivatives without invoking models for the astrophysical sources themselves. The 21 cm absorption signal is most easily interpreted, setting strong limits on the heating rate density of the universe with a measurement of its redshift alone, independent of the ionization history or details of the Lyα background evolution. In a companion paper, we extend these results, focusing on the confidence with which one can infer source emissivities from IGM properties.},
doi = {10.1088/0004-637X/777/2/118},
url = {https://www.osti.gov/biblio/22270601}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 777,
place = {United States},
year = {2013},
month = {11}
}