Second AGILE catalogue of gamma-ray sources^⋆

¹ INAF-OAS Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
e-mail: andrea.bulgarelli@inaf.it
² ASI Space Science Data Center (SSDC), Via del Politecnico snc, 00133 Roma, Italy
³ INAF-Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy
⁴ INAF-IAPS Roma, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
⁵ Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
⁶ INFN Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
⁷ Consorzio Interuniversitario Fisica Spaziale (CIFS), Villa Gualino - v.le Settimio Severo 63, 10133 Torino, Italy
⁸ INAF–IASF Milano, Via E. Bassini 15, 20133 Milano, Italy
⁹ INFN Pavia, Via Bassi 6, 27100 Pavia, Italy
¹⁰ INAF–Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, CA, Italy
¹¹ INAF–Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, LC, Italy
¹² CISAS, University of Padova, Padova, Italy
¹³ Dipartimento di Fisica, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
¹⁴ INFN, sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
¹⁵ School of Physics, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein stateJohannesburg 2050, South Africa
¹⁶ ASI, Via del Politecnico snc, 00133 Roma, Italy

Received: 27 August 2018
Accepted: 12 March 2019

Abstract

Aims. We present the second AGILE–GRID catalogue (2AGL) of γ-ray sources in the energy range 100 MeV–10 GeV.

Methods. With respect to previous AGILE–GRID catalogues, the current 2AGL catalogue is based on the first 2.3 years of science data from the AGILE mission (the so-called pointing mode) and incorporates more data and several analysis improvements, including better calibrations at the event reconstruction level, an updated model for the Galactic diffuse γ-ray emission, a refined procedure for point-like source detection, and the inclusion of a search for extended γ-ray sources.

Results. The 2AGL catalogue includes 175 high-confidence sources (above 4σ significance) with their location regions and spectral properties and a variability analysis with four-day light curves for the most significant. Relying on the error region of each source position, including systematic uncertainties, 122 sources are considered as positionally associated with known counterparts at different wavelengths or detected by other γ-ray instruments. Among the identified or associated sources, 62 are active galactic nuclei (AGNs) of the blazar class. Pulsars represent the largest Galactic source class, with 41 associated pulsars, 7 of which have detected pulsation; 8 supernova remnants and 4 high-mass X-ray binaries have also been identified. A substantial number of 2AGL sources are unidentified: for 53 sources no known counterpart is found at different wavelengths. Among these sources, we discuss a subclass of 29 AGILE–GRID–only γ-ray sources that are not present in 1FGL, 2FGL, or 3FGL catalogues; the remaining sources are unidentified in both 2AGL and 3FGL catalogues. We also present an extension of the analysis of 2AGL sources detected in the energy range 50–100 MeV.