Degree-scale galactic radio emission at 122 MHz around the North Celestial Pole with LOFAR-AARTFAAC
| العنوان: | Degree-scale galactic radio emission at 122 MHz around the North Celestial Pole with LOFAR-AARTFAAC |
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| المؤلفون: | B. K. Gehlot, L. V. E. Koopmans, A. R. Offringa, H. Gan, R. Ghara, S. K. Giri, M. Kuiack, F. G. Mertens, M. Mevius, R. Mondal, V. N. Pandey, A. Shulevski, R. A. M. J. Wijers, S. Yatawatta |
| المساهمون: | High Energy Astrophys. & Astropart. Phys (API, FNWI), API Other Research (FNWI), Astronomy, Kapteyn Astronomical Institute |
| المصدر: | Astronomy & Astrophysics, 662:A97. EDP Sciences Astronomy & Astrophysics, 662:A97 Astronomy and astrophysics, 662:A97. EDP Sciences |
| سنة النشر: | 2022 |
| مصطلحات موضوعية: | Cosmology and Nongalactic Astrophysics (astro-ph.CO), Dark Ages, Techniques: Interferometric, Astrophysics::High Energy Astrophysical Phenomena, Radio Continuum: ISM, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Dark ages, reionization, first stars, Methods: Statistical, Radio Continuum: General, Reionization, Methods: Observational, Space and Planetary Science, First Stars, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics |
| الوصف: | Aims: Contamination from bright diffuse Galactic thermal and non-thermal radio emission poses crucial challenges in experiments aiming to measure the 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization. If not included in calibration, this diffuse emission can severely impact the analysis and signal extraction in 21-cm experiments. We examine large-scale diffuse Galactic emission at 122~MHz, around the North Celestial Pole, using the AARTFAAC-HBA system. Methods: In this pilot project, we present the first-ever wide-field image produced with a single sub-band of the data recorded with the AARTFAAC-HBA. We demonstrate two methods: multiscale CLEAN and shapelet decomposition, to model the diffuse emission revealed in the image. We use angular power spectrum metrics to quantify different components of the emission and compare the performance of the two diffuse structure modelling approaches. Results: We observe that the point sources dominate the angular power spectrum ($\ell(\ell+1)C_{\ell}/2\pi\equiv \Delta^2(\ell)$) of the emission in the field on scales $\ell\gtrsim 60$ ($\lesssim 3$~degree). The angular power spectrum after subtraction of compact sources is flat within $20\lesssim \ell \lesssim200$ range, suggesting that the residual power is dominated by the diffuse emission on scales $\ell\lesssim200$. The residual diffuse emission has a brightness temperature variance of $\Delta^2_{\ell=180} = (145.64 \pm 13.61)~{\rm K}^2$ at 122~MHz on angular scales of 1~degree, and is consistent with a power-law following $C_{\ell}\propto \ell^{-2.0}$ in $20\lesssim \ell \lesssim200$ range. We also find that, in the current setup, the multiscale CLEAN is suitable to model the compact and diffuse structures on a wide range of angular scales, whereas the shapelet decomposition method better models the large scales, which are of the order of a few degrees and wider. Comment: 11 pages, 9 figures, accepted (A&A) |
| وصف الملف: | application/pdf |
| اللغة: | English |
| تدمد: | 0004-6361 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::12aaa5ba5ed2e35717a5c31016b90443 https://hdl.handle.net/1887/3561903 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....12aaa5ba5ed2e35717a5c31016b90443 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 00046361 |
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