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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 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 |
Open Access location: | https://arxiv.org/pdf/1702.08679 |
Article Number: | ARTN 65 |
Appears in Collections: | Physics Astrophysics Faculty of Natural Sciences |