Elahi, KMA and Bharadwaj, S and Pal, S and Ghosh, A and Ali, SkS and Choudhuri, S and Chakraborty, A and Datta, A and Roy, N and Choudhury, M and Dutta, P (2024) Towards 21-cm intensity mapping at z = 2.28 with uGMRT using the tapered gridded estimator � IV. Wide-band analysis. In: Monthly Notices of the Royal Astronomical Society, 529 (4). pp. 3372-3386.
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Abstract
We present a Wide-band tapered gridded estimator (TGE), which incorporates baseline migration and variation of the primary beam pattern for neutral hydrogen (H i) 21-cm intensity mapping (IM) with large frequency bandwidth radio-interferometric observations. Here we have analysed 394 � 494 MHz (z = 1.9�2.6) uGMRT data to estimate the Multifrequency Angular Power Spectrum (MAPS) C�(�ν) from which we have removed the foregrounds using the polynomial fitting (PF) and Gaussian Process Regression (GPR) methods developed in our earlier work. Using the residual C�(�ν) to estimate the mean-squared 21-cm brightness temperature fluctuation �2(k), we find that this is consistent with 0 ± 2� in several k bins. The resulting 2� upper limit �2(k) < (4.68)2 mK2 at k = 0.219 Mpc�1 is nearly 15 times tighter than earlier limits obtained from a smaller bandwidth (24.4 MHz) of the same data. The 2� upper limit ΩH ibH i < 1.01 � 10�2 is within an order of magnitude of the value expected from independent estimates of the H i mass density ΩH i and the H i bias bHi. The techniques used here can be applied to other telescopes and frequencies, including � 150 MHz Epoch of Reionization observations. © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
| Item Type: | Journal Article |
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| Publication: | Monthly Notices of the Royal Astronomical Society |
| Publisher: | Oxford University Press |
| Additional Information: | The copyright for this article belongs to authors. |
| Keywords: | Frequency estimation; Gaussian beams; Interferometry; Mapping, Diffuse radiation; Intensity mapping; Large scale structure of universe; Methods. Data analysis; Methods:statistical; Primary beams; Technique: interferometric; Upper limits; Wide-band; Wide-band analysis, Bandwidth |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 11 Jul 2024 07:03 |
| Last Modified: | 11 Jul 2024 07:03 |
| URI: | http://eprints.iisc.ac.in/id/eprint/84808 |
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