Methods for detection and analysis of weak radio sources with single-dish radio telescopes

M. Marongiu; A. Pellizzoni; E. Egron; T. Laskar; M. Giroletti; S. Loru; A. Melis; G. Carboni; C. Guidorzi; S. Kobayashi; N. Jordana-Mitjans; A. Rossi; C. G. Mundell; R. Concu; R. Martone; L. Nicastro

doi:10.1007/s10686-020-09658-9

Methods for detection and analysis of weak radio sources with single-dish radio telescopes

M. Marongiu
, A. Pellizzoni
, E. Egron
, T. Laskar
, M. Giroletti
, S. Loru
, A. Melis
, G. Carboni
, C. Guidorzi
, S. Kobayashi
, N. Jordana-Mitjans
, A. Rossi
, C. G. Mundell
, R. Concu
, R. Martone
, L. Nicastro

Department of Physics

Università di Ferrara
International Center for Relativistic Astrophysics
INAF - Osservatorio Astronomico di Cagliari
INAF - Istituto di Radioastronomia
Osservatorio Astrofisico di Catania
Liverpool John Moores University
INAF-Istituto di Astrofisica e Planetologia Spaziali

Research output: Contribution to journal › Article › peer-review

7 Citations (SciVal)

Abstract

The detection of mJy/sub-mJy point sources is a significant challenge for single-dish radio telescopes. Detection or upper limits on the faint afterglow from GRBs or other sources at cosmological distances are important means of constraining the source modeling. Using the Sardinia Radio Telescope (SRT), we compare the sensitivity and robustness of three methods applied to the detection of faint radio sources from raster maps around a known source position: the smart ‘quick-look’ method, the ‘source extraction’ method (typical of high-energy astronomy), and the fit with a 2-D Gaussian. We developed a Python code specific for the analysis of point-like radio sources applied to the SRT C-band (6.9 GHz) observations of both undetected sources (GRB afterglows of 181201A and 190114C) and the detected Galactic X-ray binary GRS 1915 + 105. Our comparative analysis of the different detection methods made extensive use of simulations as a useful complement to actual radio observations. The best method for the SRT data analysis is the fit with a 2-D Gaussian, as it pushes down the sensitivity limits of single-dish observations – with respect to more traditional techniques – to ∼ 1.8 mJy, improving by ∼ 40 % compared with the initial value. This analysis shows that – especially for faint sources – good maps of the scanned region pre- or post-outburst are essential.

Original language	English
Pages (from-to)	159–182
Number of pages	24
Journal	Experimental Astronomy
Volume	49
Issue number	3
Early online date	20 May 2020
DOIs	https://doi.org/10.1007/s10686-020-09658-9
Publication status	Published - 1 Jun 2020

Funding

We thank the anonymous referee for helping us improve the paper. The Sardinia Radio Telescope is funded by the Department of University and Research (MIUR), the Italian Space Agency (ASI), and the Autonomous Region of Sardinia (RAS), and is operated as a National Facility by the National Institute for Astrophysics (INAF). M. Marongiu gratefully acknowledges the University of Ferrara for the financial support of his PhD scholarship. We acknowledge the support from PRIN-INAF-2016 “Towards the SKA and CTA era: the discovery, localization, and physics of transient sources”. M. Marongiu thanks P. Bergamini and G. Angora for the useful discussion about Python programming language and data analysis; moreover, M. Marongiu is very grateful to K. D. Alexander for useful conversations. We acknowledge the TAC, the scheduler and the SRT staff for approving and executing these followup campaigns.

Keywords

Faint sources
Gamma-ray Bursts
Radio astronomy
Sardinia radio telescope
Single-dish

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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Marongiu, M., Pellizzoni, A., Egron, E., Laskar, T., Giroletti, M., Loru, S., Melis, A., Carboni, G., Guidorzi, C., Kobayashi, S., Jordana-Mitjans, N., Rossi, A., Mundell, C. G., Concu, R., Martone, R., & Nicastro, L. (2020). Methods for detection and analysis of weak radio sources with single-dish radio telescopes. Experimental Astronomy, 49(3), 159–182. https://doi.org/10.1007/s10686-020-09658-9

Marongiu, M, Pellizzoni, A, Egron, E, Laskar, T, Giroletti, M, Loru, S, Melis, A, Carboni, G, Guidorzi, C, Kobayashi, S, Jordana-Mitjans, N, Rossi, A, Mundell, CG, Concu, R, Martone, R & Nicastro, L 2020, 'Methods for detection and analysis of weak radio sources with single-dish radio telescopes', Experimental Astronomy, vol. 49, no. 3, pp. 159–182. https://doi.org/10.1007/s10686-020-09658-9

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AU - Giroletti, M.

AU - Loru, S.

AU - Melis, A.

AU - Carboni, G.

AU - Guidorzi, C.

AU - Kobayashi, S.

AU - Jordana-Mitjans, N.

AU - Rossi, A.

AU - Mundell, C. G.

AU - Concu, R.

AU - Martone, R.

AU - Nicastro, L.

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Methods for detection and analysis of weak radio sources with single-dish radio telescopes

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