Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator -- IV. Wideband analysis
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| Autores principales: | , , , , , , , , , , |
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| Formato: | Preprint |
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2024
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| _version_ | 1866910805241364480 |
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| author | Elahi, Khandakar Md Asif Bharadwaj, Somnath Pal, Srijita Ghosh, Abhik Ali, Sk. Saiyad Choudhuri, Samir Chakraborty, Arnab Datta, Abhirup Roy, Nirupam Choudhury, Madhurima Dutta, Prasun |
| author_facet | Elahi, Khandakar Md Asif Bharadwaj, Somnath Pal, Srijita Ghosh, Abhik Ali, Sk. Saiyad Choudhuri, Samir Chakraborty, Arnab Datta, Abhirup Roy, Nirupam Choudhury, Madhurima Dutta, Prasun |
| contents | We present a Wideband Tapered Gridded Estimator (TGE), which incorporates baseline migration and variation of the primary beam pattern for neutral hydrogen (${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$) 21-cm intensity mapping (IM) with large frequency bandwidth radio-interferometric observations. Here we have analysed $394-494 \, {\rm MHz}$ $(z = 1.9 - 2.6)$ uGMRT data to estimate the Multi-frequency Angular Power Spectrum (MAPS) $C_\ell(Δν)$ 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 $C_\ell(Δν)$ to estimate the mean squared 21-cm brightness temperature fluctuation $Δ^2(k)$, we find that this is consistent with $0 \pm 2 σ$ in several $k$ bins. The resulting $2σ$ upper limit $Δ^2(k) < (4.68)^2 \, \rm{mK^2}$ at $k=0.219\,\rm{Mpc^{-1}}$ is nearly $15$ times tighter than earlier limits obtained from a smaller bandwidth ($24.4 \, {\rm MHz}$) of the same data. The $2σ$ upper limit $[Ω_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}} b_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}] < 1.01 \times 10^{-2}$ is within an order of magnitude of the value expected from independent estimates of the ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$ mass density $Ω_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}$ and the ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$ bias $b_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}$. The techniques used here can be applied to other telescopes and frequencies, including $\sim 150 \, {\rm MHz}$ Epoch of Reionization observations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_06736 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator -- IV. Wideband analysis Elahi, Khandakar Md Asif Bharadwaj, Somnath Pal, Srijita Ghosh, Abhik Ali, Sk. Saiyad Choudhuri, Samir Chakraborty, Arnab Datta, Abhirup Roy, Nirupam Choudhury, Madhurima Dutta, Prasun Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics We present a Wideband Tapered Gridded Estimator (TGE), which incorporates baseline migration and variation of the primary beam pattern for neutral hydrogen (${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$) 21-cm intensity mapping (IM) with large frequency bandwidth radio-interferometric observations. Here we have analysed $394-494 \, {\rm MHz}$ $(z = 1.9 - 2.6)$ uGMRT data to estimate the Multi-frequency Angular Power Spectrum (MAPS) $C_\ell(Δν)$ 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 $C_\ell(Δν)$ to estimate the mean squared 21-cm brightness temperature fluctuation $Δ^2(k)$, we find that this is consistent with $0 \pm 2 σ$ in several $k$ bins. The resulting $2σ$ upper limit $Δ^2(k) < (4.68)^2 \, \rm{mK^2}$ at $k=0.219\,\rm{Mpc^{-1}}$ is nearly $15$ times tighter than earlier limits obtained from a smaller bandwidth ($24.4 \, {\rm MHz}$) of the same data. The $2σ$ upper limit $[Ω_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}} b_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}] < 1.01 \times 10^{-2}$ is within an order of magnitude of the value expected from independent estimates of the ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$ mass density $Ω_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}$ and the ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$ bias $b_{\rm H\hspace{0.5mm}{\scriptsize {\rm I}}}$. The techniques used here can be applied to other telescopes and frequencies, including $\sim 150 \, {\rm MHz}$ Epoch of Reionization observations. |
| title | Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator -- IV. Wideband analysis |
| topic | Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2403.06736 |