Open Universe survey of Swift-XRT GRB fields: Flux-limited sample of HBL blazars^⋆

¹ Institute for Advanced Study, Technische Universität München, Lichtenbergstrasse 2a, 85748 Garching bei München, Germany
e-mail: giommipaolo@gmail.com
² Associated to the Italian Space Agency, ASI, Via del Politecnico snc, 00133 Roma, Italy
³ ICRANet, P.zza della Repubblica 10, 65122 Pescara, Italy
⁴ Tsung-Dao Lee Institute, Shanghai Jiao Tong University, 800 Dongchuan RD. Minhang District, Shanghai, PR China
⁵ Physics Department, Gubkin Russian State University (National Research University), 65 Leninsky Prospekt, Moscow 119991, Russian Federation
⁶ Italian Space Agency, ASI, Via del Politecnico snc, 00133 Roma, Italy
⁷ Space Science Data Center, SSDC, ASI, Via del Politecnico snc, 00133 Roma, Italy
⁸ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio Catone, Italy
⁹ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
¹⁰ Institute of Physics. IFLP-CONICET, Diag 113 e/63-64.(1900), La Plata, Argentina
¹¹ New York University Abu Dhabi, Abu Dhabi, UAE
¹² Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, Brazil
¹³ Jacobs University, Physics and Earth Sciences, Campus Ring 1, 28759 Bremen, Germany
¹⁴ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, Via Ugo La Malfa 153, 90146 Palermo, Italy
¹⁵ Department of Physics, University of La Plata. 49 and 115.C.C.67 (1900), La Plata, Argentina
¹⁶ United Nations Office for Outer Space Affairs, UNOOSA, Vienna, Austria
¹⁷ Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK
¹⁸ ICRANet-Armenia, Marshall Baghramian Avenue 24a, Yerevan 0019, Armenia

Received: 11 March 2020
Accepted: 3 July 2020

Abstract

Aims. The sample of serendipitous sources detected in all Swift-XRT images pointing at gamma ray bursts (GRBs) constitutes the largest existing medium-deep survey of the X-ray sky. To build such dataset we analysed all Swift X-ray images centred on GRBs and observed over a period of 15 years using automatic tools that do not require any expertise in X-ray astronomy. Besides presenting a new large X-ray survey and a complete sample of blazars, this work aims to be a step in the direction of achieving the ultimate goal of the Open Universe Initiative, which is to enable non-expert people to benefit fully from space science data, possibly extending the potential for scientific discovery, which is currently confined within a small number of highly specialised teams, to a much larger population.

Methods. We used the Swift_deepsky Docker container encapsulated pipeline to build the largest existing flux-limited and unbiased sample of serendipitous X-ray sources. Swift_deepsky runs on any laptop or desktop computer with a modern operating system. The tool automatically downloads the data and the calibration files from the archives, runs the official Swift analysis software, and produces a number of results including images, the list of detected sources, X-ray fluxes, spectral energy distribution data, and spectral slope estimations.

Results. We used our source list to build the LogN-LogS of extra-galactic sources, which perfectly matches that estimated by other satellites. Combining our survey with multi-frequency data, we selected a complete radio-flux-density-limited sample of high energy peaked blazars (HBL). The LogN-LogS built with this data set confirms that previous samples are incomplete below ∼20 mJy.