Upper limits on the 21 cm epoch of reionization power spectrum from one night with LOFAR
File(s)
Published version
OA Location
Author(s)
Type
Journal Article
Abstract
We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9–10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero ${{\rm{\Delta }}}_{{\rm{I}}}^{2}={(56\pm 13\mathrm{mK})}^{2}$ (1-σ) excess variance and a best 2-σ upper limit of ${{\rm{\Delta }}}_{21}^{2}\lt {(79.6\mathrm{mK})}^{2}$ at k = 0.053 h cMpc−1 in the range z = 9.6–10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.
Date Issued
2017-03-24
Date Acceptance
2017-02-27
Citation
Astrophysical Journal, 2017, 838 (1)
ISSN
1538-4357
Publisher
American Astronomical Society
Journal / Book Title
Astrophysical Journal
Volume
838
Issue
1
Copyright Statement
© 2017 The American Astronomical Society. All rights reserved.
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
dark ages
reionization
first stars
astro-ph.CO
astro-ph.CO
astro-ph.IM
0201 Astronomical and Space Sciences
0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
0306 Physical Chemistry (incl. Structural)
Astronomy & Astrophysics
Notes
archiveprefix: arXiv keywords: dark ages, reionization, first stars eid: 65 adsurl: http://adsabs.harvard.edu/abs/2017ApJ...838...65P adsnote: Provided by the SAO/NASA Astrophysics Data System
Publication Status
Published
Article Number
ARTN 65