UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Upper Limits on the 21cm Epoch of Reionization Power Spectrum from One Night with LOFAR

Patil, AH; Yatawatta, S; Koopmans, LVE; de Bruyn, AG; Brentjens, MA; Zaroubi, S; Asad, KMB; ... Wijnholds, SJ; + view all (2017) Upper Limits on the 21cm Epoch of Reionization Power Spectrum from One Night with LOFAR. The Astrophysical Journal , 838 (1) , Article 65. 10.3847/1538-4357/aa63e7. Green open access

[thumbnail of Patil_Upper_Limits_21cm.pdf]
Preview
Text
Patil_Upper_Limits_21cm.pdf - Published version

Download (3MB) | Preview

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.

Type: Article
Title: Upper Limits on the 21cm Epoch of Reionization Power Spectrum from One Night with LOFAR
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/aa63e7
Publisher version: https://doi.org/10.3847/1538-4357/aa63e7
Language: English
Additional information: This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: dark ages, reionization, first stars
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/1556637
Downloads since deposit
43Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item