Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data

Baldini L, Ballet J, Bastieri D, Becerra Gonzalez J, Bellazzini R, Berretta A, Bissaldi E, Blandford RD, Bloom ED, Bonino R, Bottacini E, Bruel P, Buson S, Cameron RA, Caraveo PA, Cavazzuti E, Chen S, Chiaro G, Ciangottini D, Cibario N, Ciprini S, Cristarella Orestano P, Crnogorcevic M, Cutini S, D'Ammando F, De La Torre Luque P, De Palma F, Digel SW, Di Lalla N, Dirirsa F, Di Venere L, Dominguez A, Fiori A, Fleischhack H, Franckowiak A, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Germani S, Giglietto N, Giordano F, Giroletti M, Green D, Grenier IA, Griffin S, Guiriec S, Gustafsson M, Hewitt JW, Horan D, Imazawa R, Johannesson G, Kerr M, Kocevski D, Kuss M, Larsson S, Latronico L, Li J, Liodakis I, Longo F, Loparco F, Lovellette MN, Lubrano P, Maldera S, Manfreda A, Marti-Devesa G, Matake H, Mazziotta MN, Mereu I, Meyer M, Mirabal N, Mitthumsiri W, Mizuno T, Monzani ME, Morselli A, Moskalenko IV, Nagasawa S, Negro M, Ojha R, Orienti M, Orlando E, Palatiello M, Paliya V, Paneque D, Pei Z, Persic M, Pesce-Rollins M, Petrosian V, Poon H, Porter TA, Principe G, Racusin JL, Raino S, Rando R, Rani B, Razzano M, Razzaque S, Reimer A, Reimer O, Saz Parkinson PM, Scotton L, Serini D, Sgro C, Siskind EJ, Spandre G, Spinelli P, Suson DJ, Tajima H, Tak D, Torres DF, Tosti G, Troja E, Wood K, Yassine M, Zaharijas G (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Book Volume: 256

Journal Issue: 1

DOI: 10.3847/1538-4365/ac072a

Abstract

We present the first Fermi Large Area Telescope (LAT) catalog of long-term gamma-ray transient sources (1FLT). This comprises sources that were detected on monthly time intervals during the first decade of Fermi-LAT operations. The monthly timescale allows us to identify transient and variable sources that were not yet reported in other Fermi-LAT catalogs. The monthly data sets were analyzed using a wavelet-based source detection algorithm that provided the candidate new transient sources. The search was limited to the extragalactic regions of the sky to avoid the dominance of the Galactic diffuse emission at low Galactic latitudes. The transient candidates were then analyzed using the standard Fermi-LAT maximum likelihood analysis method. All sources detected with a statistical significance above 4 sigma in at least one monthly bin were listed in the final catalog. The 1FLT catalog contains 142 transient gamma-ray sources that are not included in the 4FGL-DR2 catalog. Many of these sources (102) have been confidently associated with active galactic nuclei (AGNs): 24 are associated with flat-spectrum radio quasars, 1 with a BL Lac object, 70 with blazars of uncertain type, 3 with radio galaxies, 1 with a compact steep-spectrum radio source, 1 with a steep-spectrum radio quasar, and 2 with AGNs of other types. The remaining 40 sources have no candidate counterparts at other wavelengths. The median gamma-ray spectral index of the 1FLT-AGN sources is softer than that reported in the latest Fermi-LAT AGN general catalog. This result is consistent with the hypothesis that detection of the softest gamma-ray emitters is less efficient when the data are integrated over year-long intervals.

Authors with CRIS profile

Involved external institutions

University of Pisa / Università di Pisa (UniPi) Italy (IT) University of Paris 4 - Paris-Sorbonne / Université paris IV Paris-Sorbonne France (FR) National Institute for Nuclear Physics / Istituto Nazionale di Fisica Nucleare (INFN) Italy (IT) Instituto de Astrofísica de Canarias (IAC) Spain (ES) Università degli Studi di Perugia Italy (IT) University of Bari Aldo Moro / Università degli Studi di Bari Aldo Moro Italy (IT) Stanford University United States (USA) (US) École Polytechnique - Université Paris-Saclay France (FR) Julius-Maximilians-Universität Würzburg Germany (DE) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) Italian Space Agency / Agenzia Spaziale Italiana (ASI) Italy (IT) Università del Salento Italy (IT) University of Savoy Mont Blanc / Université Savoie Mont Blanc France (FR) Catholic University of America United States (USA) (US) Ruhr-Universität Bochum (RUB) Germany (DE) Hiroshima University Japan (JP) Max-Planck-Institut für Physik (Werner-Heisenberg-Institut, MPP) / Max Planck Institute for Physics Germany (DE) National Aeronautics and Space Administration (NASA) United States (USA) (US) Georg-August-Universität Göttingen Germany (DE) University of North Florida (UNF) United States (USA) (US) University of Iceland (UI) / Háskóli Íslands Iceland (IS) U.S. Naval Research Laboratory United States (USA) (US) Royal Institute of Technology / Kungliga Tekniska Högskolan (KTH) Sweden (SE) Deutsches Elektronen-Synchrotron DESY Germany (DE) University of Maryland United States (USA) (US) Universidad Complutense de Madrid (UCM) Spain (ES) University of California Santa Cruz United States (USA) (US) University of Turku / Turun yliopisto Finland (FI) Leopold-Franzens-Universität Innsbruck / University of Innsbruck Austria (AT) George Washington University (GWU) United States (USA) (US) Mahidol University / มหาวิทยาลัยมหิดล Thailand (TH) University of Tokyo Japan (JP) University of Padua / Universita degli Studi di Padova Italy (IT) University of Johannesburg South Africa (ZA) University of Montpellier / Université Montpellier France (FR) NYCB Real-Time Computing, Inc. United States (USA) (US) Purdue University Northwest / Purdue University Calumet United States (USA) (US) Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC) Spain (ES) Praxis, Inc. United States (USA) (US)

How to cite

APA:

Baldini, L., Ballet, J., Bastieri, D., Becerra Gonzalez, J., Bellazzini, R., Berretta, A.,... Zaharijas, G. (2021). Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data. Astrophysical Journal Supplement Series, 256(1). https://dx.doi.org/10.3847/1538-4365/ac072a

MLA:

Baldini, Luca, et al. "Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data." Astrophysical Journal Supplement Series 256.1 (2021).

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