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Upper limits on the 21 cm epoch of reionization power spectrum from one night with LOFAR

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Title: Upper limits on the 21 cm epoch of reionization power spectrum from one night with LOFAR
Authors: Patil, AH
Yatawatta, S
Koopmans, LVE
De Bruyn, AG
Brentjens, MA
Zaroubi, S
Asad, KMB
Hatef, M
Jelić, V
Mevius, M
Offringa, AR
Pandey, VN
Vedantham, H
Abdalla, FB
Brouw, WN
Chapman, E
Ciardi, B
Gehlot, BK
Ghosh, A
Harker, G
Iliev, IT
Kakiichi, K
Majumdar, S
Mellema, G
Silva, MB
Schaye, J
Vrbanec, D
Wijnholds, SJ
Item 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.
Issue Date: 24-Mar-2017
Date of Acceptance: 27-Feb-2017
URI: http://hdl.handle.net/10044/1/46063
DOI: 10.3847/1538-4357/aa63e7
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.
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
dark ages
first stars
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
Open Access location: https://arxiv.org/pdf/1702.08679
Article Number: ARTN 65
Appears in Collections:Physics
Faculty of Natural Sciences