A Tapered Gridded Estimator (TGE) for the multifrequency angular power spectrum (MAPS) and the cosmological H I 21cm power spectrum
Abstract
In this work, we present a new approach to estimate the power spectrum P(k) of redshifted H I 21cm brightness temperature fluctuations. The MAPS C_{ℓ}(ν_{a}, ν_{b}) completely quantifies the secondorder statistics of the sky signal under the assumption that the signal is statistically homogeneous and isotropic on the sky. Here, we generalize an already existing visibility based estimator for C_{ℓ}, namely TGE, to develop an estimator for C_{ℓ}(ν_{a}, ν_{b}) . The 21cm power spectrum is the Fourier transform of C_{ℓ}(∆ν) with respect to ∆ν = │ν_{a}  ν_{b}│, and we use this to estimate P(k). Using simulations of 150 MHz GMRT observations, we find that this estimator is able to recover P(k) with an accuracy of 520 {{ per cent}} over a reasonably large k range even when the data in 80 {{ per cent}} randomly chosen frequency channels are flagged.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 March 2019
 DOI:
 10.1093/mnras/sty3501
 arXiv:
 arXiv:1812.08801
 Bibcode:
 2019MNRAS.483.5694B
 Keywords:

 methods: data analysis;
 methods: statistical;
 techniques: interferometric;
 diffuse radiation;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages, 4 figures. Accepted for publication in MNRAS. The definitive version will be available at https://academic.oup.com/mnras