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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
New limits on 21 cm epoch of reionization from paper-32 consistent with an x-ray heated intergalactic medium at z = 7.7
Astrophysical Journal, Volume 788, No. 2, Article 106, Year 2014
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Description
We present new constraints on the 21 cm Epoch of Reionization (EoR) power spectrum derived from three months of observing with a 32 antenna, dual-polarization deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. In this paper, we demonstrate the efficacy of the delay-spectrum approach to avoiding foregrounds, achieving over eight orders of magnitude of foreground suppression (in mK2). Combining this approach with a procedure for removing off-diagonal covariances arising from instrumental systematics, we achieve a best 2σ upper limit of (41 mK)2 for k = 0.27 h Mpc-1 at z = 7.7. This limit falls within an order of magnitude of the brighter predictions of the expected 21 cm EoR signal level. Using the upper limits set by these measurements, we generate new constraints on the brightness temperature of 21 cm emission in neutral regions for various reionization models. We show that for several ionization scenarios, our measurements are inconsistent with cold reionization. That is, heating of the neutral intergalactic medium (IGM) is necessary to remain consistent with the constraints we report. Hence, we have suggestive evidence that by z = 7.7, the H I has been warmed from its cold primordial state, probably by X-rays from high-mass X-ray binaries or miniquasars. The strength of this evidence depends on the ionization state of the IGM, which we are not yet able to constrain. This result is consistent with standard predictions for how reionization might have proceeded. © 2014. The American Astronomical Society. All rights reserved..
Authors & Co-Authors
Parsons, Aaron R.
United States, Berkeley
University of California, Berkeley
Liu, Adrian
United States, Berkeley
University of California, Berkeley
Aguirre, James E.
United States, Philadelphia
University of Pennsylvania
Ali, Zaki S.
United States, Berkeley
University of California, Berkeley
Bradley, Richard F.
United States, Charlottesville
University of Virginia
United States, Charlottesville
National Radio Astronomy Observatory
Chris L. Carilli, Christopher L.
United States, Socorro
National Radio Astronomy Observatory Socorro
DeBoer, David R.
United States, Berkeley
University of California, Berkeley
Dexter, Matt R.
United States, Berkeley
University of California, Berkeley
Gugliucci, Nicole E.
United States, Charlottesville
University of Virginia
Jacobs, Daniel C.
United States, Tempe
School of Earth and Space Exploration
Klima, Pat J.
United States, Charlottesville
National Radio Astronomy Observatory
MacMahon, David Harold Edward
United States, Berkeley
University of California, Berkeley
Manley, Jason R.
South Africa, Cape Town
Conservation South Africa
Moore, David F.
United States, Philadelphia
University of Pennsylvania
Pober, Jonathan C.
United States, Berkeley
University of California, Berkeley
Stefan, Irina I.
United Kingdom, Cambridge
Department of Physics
Walbrugh, William P.
South Africa, Cape Town
Conservation South Africa
Statistics
Citations: 147
Authors: 17
Affiliations: 8
Identifiers
Doi:
10.1088/0004-637X/788/2/106
ISSN:
0004637X
e-ISSN:
15384357
Research Areas
Environmental
Study Locations
South Africa