Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal

Raul A. Monsalve, Alan E.E. Rogers, Judd Bowman, Thomas J. Mozdzen

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts 14.8 ≥ z ≥ 6.5. We derive our constraints from low-foreground observations of the average sky brightness spectrum conducted with the EDGES High-band instrument between 2015 September 7 and October 26. Observations were calibrated by accounting for the effects of antenna beam chromaticity, antenna and ground losses, signal reflections, and receiver parameters. We evaluate the consistency between the spectrum and phenomenological models for the global 21 cm signal. For tanh-based representations of the ionization history during the epoch of reionization, we rule out, at ≥2s significance, models with duration of up to Δz = 1 at z ≈ 8.5 and higher than Δz = 0.4 across most of the observed redshift range under the usual assumption that the 21 cm spin temperature is much larger than the temperature of the cosmic microwave background during reionization. We also investigate a cold intergalactic medium (IGM) scenario that assumes perfect Lyα coupling of the 21 cm spin temperature to the temperature of the IGM, but that the latter is not heated by early stars or stellar remants. Under this assumption, we reject tanh-based reionization models of duration Δz ≲ 2 over most of the observed redshift range. Finally, we explore and reject a broad range of Gaussian models for the 21 cm absorption feature expected in the First Light era. As an example, we reject 100 mK Gaussians with duration (full width at half maximum) Δz ≤ 4 over the range 14.2 ≥ z ≥ 6.5 at ≥2s significance.

Original languageEnglish (US)
Article number64
JournalAstrophysical Journal
Volume847
Issue number1
DOIs
StatePublished - Sep 20 2017

Fingerprint

spin temperature
intergalactic media
antenna
antennas
temperature
sky brightness
signal reflection
early stars
ionization
receivers
time measurement
histories
hydrogen
microwaves
history
loss
cold
effect
microwave
parameter

Keywords

  • cosmology: observations
  • early universe
  • methods: data analysis

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal. / Monsalve, Raul A.; Rogers, Alan E.E.; Bowman, Judd; Mozdzen, Thomas J.

In: Astrophysical Journal, Vol. 847, No. 1, 64, 20.09.2017.

Research output: Contribution to journalArticle

Monsalve, Raul A. ; Rogers, Alan E.E. ; Bowman, Judd ; Mozdzen, Thomas J. / Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal. In: Astrophysical Journal. 2017 ; Vol. 847, No. 1.
@article{0647764c82c7485db31638ff617a413d,
title = "Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal",
abstract = "We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts 14.8 ≥ z ≥ 6.5. We derive our constraints from low-foreground observations of the average sky brightness spectrum conducted with the EDGES High-band instrument between 2015 September 7 and October 26. Observations were calibrated by accounting for the effects of antenna beam chromaticity, antenna and ground losses, signal reflections, and receiver parameters. We evaluate the consistency between the spectrum and phenomenological models for the global 21 cm signal. For tanh-based representations of the ionization history during the epoch of reionization, we rule out, at ≥2s significance, models with duration of up to Δz = 1 at z ≈ 8.5 and higher than Δz = 0.4 across most of the observed redshift range under the usual assumption that the 21 cm spin temperature is much larger than the temperature of the cosmic microwave background during reionization. We also investigate a cold intergalactic medium (IGM) scenario that assumes perfect Lyα coupling of the 21 cm spin temperature to the temperature of the IGM, but that the latter is not heated by early stars or stellar remants. Under this assumption, we reject tanh-based reionization models of duration Δz ≲ 2 over most of the observed redshift range. Finally, we explore and reject a broad range of Gaussian models for the 21 cm absorption feature expected in the First Light era. As an example, we reject 100 mK Gaussians with duration (full width at half maximum) Δz ≤ 4 over the range 14.2 ≥ z ≥ 6.5 at ≥2s significance.",
keywords = "cosmology: observations, early universe, methods: data analysis",
author = "Monsalve, {Raul A.} and Rogers, {Alan E.E.} and Judd Bowman and Mozdzen, {Thomas J.}",
year = "2017",
month = "9",
day = "20",
doi = "10.3847/1538-4357/aa88d1",
language = "English (US)",
volume = "847",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal

AU - Monsalve, Raul A.

AU - Rogers, Alan E.E.

AU - Bowman, Judd

AU - Mozdzen, Thomas J.

PY - 2017/9/20

Y1 - 2017/9/20

N2 - We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts 14.8 ≥ z ≥ 6.5. We derive our constraints from low-foreground observations of the average sky brightness spectrum conducted with the EDGES High-band instrument between 2015 September 7 and October 26. Observations were calibrated by accounting for the effects of antenna beam chromaticity, antenna and ground losses, signal reflections, and receiver parameters. We evaluate the consistency between the spectrum and phenomenological models for the global 21 cm signal. For tanh-based representations of the ionization history during the epoch of reionization, we rule out, at ≥2s significance, models with duration of up to Δz = 1 at z ≈ 8.5 and higher than Δz = 0.4 across most of the observed redshift range under the usual assumption that the 21 cm spin temperature is much larger than the temperature of the cosmic microwave background during reionization. We also investigate a cold intergalactic medium (IGM) scenario that assumes perfect Lyα coupling of the 21 cm spin temperature to the temperature of the IGM, but that the latter is not heated by early stars or stellar remants. Under this assumption, we reject tanh-based reionization models of duration Δz ≲ 2 over most of the observed redshift range. Finally, we explore and reject a broad range of Gaussian models for the 21 cm absorption feature expected in the First Light era. As an example, we reject 100 mK Gaussians with duration (full width at half maximum) Δz ≤ 4 over the range 14.2 ≥ z ≥ 6.5 at ≥2s significance.

AB - We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts 14.8 ≥ z ≥ 6.5. We derive our constraints from low-foreground observations of the average sky brightness spectrum conducted with the EDGES High-band instrument between 2015 September 7 and October 26. Observations were calibrated by accounting for the effects of antenna beam chromaticity, antenna and ground losses, signal reflections, and receiver parameters. We evaluate the consistency between the spectrum and phenomenological models for the global 21 cm signal. For tanh-based representations of the ionization history during the epoch of reionization, we rule out, at ≥2s significance, models with duration of up to Δz = 1 at z ≈ 8.5 and higher than Δz = 0.4 across most of the observed redshift range under the usual assumption that the 21 cm spin temperature is much larger than the temperature of the cosmic microwave background during reionization. We also investigate a cold intergalactic medium (IGM) scenario that assumes perfect Lyα coupling of the 21 cm spin temperature to the temperature of the IGM, but that the latter is not heated by early stars or stellar remants. Under this assumption, we reject tanh-based reionization models of duration Δz ≲ 2 over most of the observed redshift range. Finally, we explore and reject a broad range of Gaussian models for the 21 cm absorption feature expected in the First Light era. As an example, we reject 100 mK Gaussians with duration (full width at half maximum) Δz ≤ 4 over the range 14.2 ≥ z ≥ 6.5 at ≥2s significance.

KW - cosmology: observations

KW - early universe

KW - methods: data analysis

UR - http://www.scopus.com/inward/record.url?scp=85030152981&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85030152981&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa88d1

DO - 10.3847/1538-4357/aa88d1

M3 - Article

AN - SCOPUS:85030152981

VL - 847

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 64

ER -