Browsing by Author "M. N. Lovellette"

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    Catalog of Long-term Transient Sources in the First 10 yr of Fermi-LAT Data
    (2021-09-01) The Fermi-Lat Collaboration; L. Baldini; J. Ballet; D. Bastieri; J. Becerra Gonzalez; R. Bellazzini; A. Berretta; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; P. Bruel; S. Buson; R. A. Cameron; P. A. Caraveo; E. Cavazzuti; S. Chen; G. Chiaro; D. Ciangottini; N. Cibario; S. Ciprini; P. Cristarella Orestano; M. Crnogorcevic; S. Cutini; F. D'Ammando; P. De La Torre Luque; F. De Palma; S. W. Digel; N. Di Lalla; F. Dirirsa; L. Di Venere; A. Domínguez; A. Fiori; H. Fleischhack; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; S. Germani; N. Giglietto; F. Giordano; M. Giroletti; D. Green; I. A. Grenier; S. Griffin; S. Guiriec; M. Gustafsson; J. W. Hewitt; D. Horan; R. Imazawa; G. Jóhannesson; M. Kerr; D. Kocevski; M. Kuss; S. Larsson; L. Latronico; J. Li; I. Liodakis; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; S. Maldera; A. Manfreda; G. Martí-Devesa; H. Matake; M. N. Mazziotta; I. Mereu; M. Meyer; N. Mirabal; W. Mitthumsiri; T. Mizuno; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Nagasawa; M. Negro; R. Ojha; M. Orienti; E. Orlando; M. Palatiello; V. Paliya; D. Paneque; Z. Pei; M. Persic; M. Pesce-Rollins; V. Petrosian; H. Poon; T. A. Porter; G. Principe; J. L. Racusin; S. Rain; R. Rando; B. Rani; M. Razzano; S. Razzaque; A. Reimer; Oskar Klein Centre; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Lecce; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Universite Paris-Saclay; Aryabhatta Research Institute of Observational Sciences; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Korea Astronomy and Space Science Institute; Raunvísindastofnun Háskólans; Agenzia Spaziale Italiana; Georg-August-Universität Göttingen; Hiroshima University; Deutsches Elektronen-Synchrotron (DESY); Osservatorio Astronomico di Trieste; Università di Pisa; Politecnico di Bari; Universidad Complutense de Madrid; Naval Research Laboratory; Università degli Studi di Udine; SLAC National Accelerator Laboratory; The University of Tokyo; University of Maryland, Baltimore County (UMBC); Universita del Salento; Catholic University of America; American University; University of Maryland, College Park; Université Savoie Mont Blanc; Università degli Studi di Trieste; Högskolan Dalarna; École polytechnique; Mahidol University; Julius-Maximilians-Universität Würzburg; Istituto Di Radioastronomia, Bologna; Università degli Studi di Torino; NASA Marshall Space Flight Center; Instituto Astrofisico de Canarias; Universität Innsbruck; Max Planck Institute for Physics (Werner Heisenberg Institute); Turun yliopisto; NASA Goddard Space Flight Center; Ruhr-Universitat Bochum; The George Washington University; Università degli Studi di Perugia; The Royal Institute of Technology (KTH); Friedrich-Alexander-Universität Erlangen-Nürnberg; University of Johannesburg; Università degli Studi di Padova; University of North Florida
    We present the first Fermi Large Area Telescope (LAT) catalog of long-term γ-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 4σ in at least one monthly bin were listed in the final catalog. The 1FLT catalog contains 142 transient γ-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 γ-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 γ-ray emitters is less efficient when the data are integrated over year-long intervals.
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    CONTEMPORANEOUS BROADBAND OBSERVATIONS of THREE HIGH-REDSHIFT BL LAC OBJECTS
    (2016-03-20) M. Ackermann; M. Ajello; H. An; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; E. Bissaldi; R. D. Blandford; R. Bonino; J. Bregeon; R. J. Britto; P. Bruel; R. Buehler; G. A. Caliandro; R. A. Cameron; M. Caragiulo; P. A. Caraveo; E. Cavazzuti; C. Cecchi; E. Charles; A. Chekhtman; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; F. Costanza; S. Cutini; F. D'Ammando; A. De Angelis; F. De Palma; R. Desiante; M. Di Mauro; L. Di Venere; A. Dominguez; P. S. Drell; C. Favuzzi; S. J. Fegan; E. C. Ferrara; J. Finke; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; D. Green; I. A. Grenier; S. Guiriec; D. Horan; G. Jóhannesson; M. Katsuragawa; M. Kuss; S. Larsson; L. Latronico; J. Li; L. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; J. Magill; S. Maldera; A. Manfreda; M. Mayer; M. N. Mazziotta; P. F. Michelson; N. Mirabal; W. Mitthumsiri; T. Mizuno; M. E. Monzani; A. Morselli; I. V. Moskalenko; M. Negro; E. Nuss; Deutsche Elektronen-Synchrotron; Clemson University; Kavli Institute for Particle Astrophysics and Cosmology; Università di Pisa; Istituto Nazionale di Fisica Nucleare, Roma; Universita degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Università degli Studi di Torino; Laboratoire Univers et Particules de Montpellier; University of Johannesburg; Laboratoire Leprince-Ringuet; Consorzio Interuniversitario per la Fisica Spaziale (CIFS); Università degli Studi di Bari; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Agenzia Spaziale Italiana; Universita degli Studi di Perugia; George Mason University, Fairfax Campus; Osservatorio Astronomico di Roma; Istituto Di Radioastronomia, Bologna; Alma Mater Studiorum Università di Bologna; Universita degli Studi di Udine; Università degli Studi di Napoli Federico II; NASA Goddard Space Flight Center; Naval Research Laboratory; University of Maryland; Institut de Recherche sur les Lois Fondamentales de l'Univers; University Science Institute Reykjavik; JAXA Institute of Space and Astronautical Science; The Royal Institute of Technology (KTH); Oskar Klein Centre for Cosmoparticle Physics; Universitat Autònoma de Barcelona; Mahidol University; Hiroshima University; Max Planck Institut fur Physik (Werner-Heisenberg-Institut); Medizinische Universitat Innsbruck; Max Planck Institut fur extraterrestrische Physik; NYCB Realtime Computing Inc.; Jet Propulsion Laboratory, California Institute of Technology; Institucio Catalana de Recerca I Estudis Avancats
    © 2016. The American Astronomical Society. All rights reserved. We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1-1855 (z = 0.689), 3FGL J0630.9-2406 (z≳ 1.239), and 3FGL J0811.2-7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the gigaelectronvolt Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high-ultraviolet models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest-redshift source 3FGL J0630.9-2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components. For 3FGL J0811.2-7529, we also discover a nearby serendipitous source in the X-ray data, which is almost certainly another lower synchrotron peak frequency (vpksy) BL Lac, that may contribute flux in the Fermi band. Since our sources are unusual high-luminosity, moderate vpksy BL Lacs, we compare these quantities and the Compton dominance, the ratio of peak inverse Compton to peak synchrotron luminosities (LpkIC/Lpksy), with those of the full Fermi BL Lac population.
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    A Decade of Gamma-Ray Bursts Observed by Fermi-LAT: The Second GRB Catalog
    (2019-06-10) M. Ajello; M. Arimoto; M. Axelsson; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; P. N. Bhat; E. Bissaldi; R. D. Blandford; R. Bonino; J. Bonnell; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; R. A. Cameron; R. Caputo; P. A. Caraveo; E. Cavazzuti; S. Chen; C. C. Cheung; G. Chiaro; S. Ciprini; D. Costantin; M. Crnogorcevic; S. Cutini; M. Dainotti; F. D'Ammando; P. D.L. Torre Luque; F. D. Palma; A. Desai; R. Desiante; N. Di Lalla; L. Di Venere; F. Fana Dirirsa; S. J. Fegan; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; D. Green; I. A. Grenier; J. E. Grove; S. Guiriec; E. Hays; J. W. Hewitt; D. Horan; G. Jóhannesson; D. Kocevski; M. Kuss; L. Latronico; J. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; S. Maldera; A. Manfreda; G. Marti-Devesa; M. N. Mazziotta; I. Mereu; M. Meyer; P. F. Michelson; N. Mirabal; W. Mitthumsiri; T. Mizuno; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; M. Negro; E. Nuss; M. Ohno; N. Omodei; M. Orienti; E. Orlando; M. Palatiello; V. S. Paliya; D. Paneque; M. Persic; M. Pesce-Rollins; V. Petrosian; F. Piron; S. Poolakkil; H. Poon; T. A. Porter; G. Principe; J. L. Racusin; S. Raino; R. Rando; M. Razzano; S. Razzaque; A. Reimer; O. Reimer; Center for Space Plasma and Aeronomic Research; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Laboratoire Univers et Particules de Montpellier; Universite Paris-Saclay; Laboratoire Leprince-Ringuet; Kavli Institute for Particle Astrophysics and Cosmology; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; University Science Institute Reykjavik; Agenzia Spaziale Italiana; Hiroshima University; Deutsches Elektronen-Synchrotron (DESY); Osservatorio Astronomico di Trieste; Università di Pisa; Stockholms universitet; Alma Mater Studiorum Università di Bologna; Naval Research Laboratory; Clemson University; University of Maryland, Baltimore County; Kanazawa University; Universitat Autònoma de Barcelona; Università degli Studi di Bari; Istituto Nazionale di Fisica Nucleare - INFN; University of Maryland; Università degli Studi di Trieste; Mahidol University; Istituto Di Radioastronomia, Bologna; Università degli Studi di Torino; Max-Planck-Institut für Physik (Werner-Heisenberg-Institut); Medizinische Universitat Innsbruck; NASA Goddard Space Flight Center; The George Washington University; Università degli Studi di Perugia; The Royal Institute of Technology (KTH); Friedrich-Alexander-Universität Erlangen-Nürnberg; University of Johannesburg; Università degli Studi di Padova; University of North Florida
    © 2019. The American Astronomical Society. All rights reserved. The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present the second catalog of LAT-detected GRBs, covering the first 10 yr of operations, from 2008 to 2018 August 4. A total of 186 GRBs are found; of these, 91 show emission in the range 30-100 MeV (17 of which are seen only in this band) and 169 are detected above 100 MeV. Most of these sources were discovered by other instruments (Fermi/GBM, Swift/BAT, AGILE, INTEGRAL) or reported by the Interplanetary Network (IPN); the LAT has independently triggered on four GRBs. This catalog presents the results for all 186 GRBs. We study onset, duration, and temporal properties of each GRB, as well as spectral characteristics in the 100 MeV-100 GeV energy range. Particular attention is given to the photons with the highest energy. Compared with the first LAT GRB catalog, our rate of detection is significantly improved. The results generally confirm the main findings of the first catalog: the LAT primarily detects the brightest GBM bursts, and the high-energy emission shows delayed onset as well as longer duration. However, in this work we find delays exceeding 1 ks and several GRBs with durations over 10 ks. Furthermore, the larger number of LAT detections shows that these GRBs not only cover the high-fluence range of GBM-detected GRBs but also sample lower fluences. In addition, the greater number of detected GRBs with redshift estimates allows us to study their properties in both the observer and rest frames. Comparison of the observational results with theoretical predictions reveals that no model is currently able to explain all results, highlighting the role of LAT observations in driving theoretical models.
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    DEEP MORPHOLOGICAL and SPECTRAL STUDY of the SNR RCW 86 with FERMI-LAT
    (2016-03-10) M. Ajello; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; E. Bissaldi; E. D. Bloom; R. Bonino; E. Bottacini; T. J. Brandt; J. Bregeon; P. Bruel; R. Buehler; G. A. Caliandro; R. A. Cameron; M. Caragiulo; E. Cavazzuti; E. Charles; A. Chekhtman; S. Ciprini; J. Cohen-Tanugi; B. Condon; F. Costanza; S. Cutini; F. D'Ammando; F. De Palma; R. Desiante; N. Di Lalla; M. Di Mauro; L. Di Venere; P. S. Drell; G. Dubner; D. Dumora; L. Duvidovich; C. Favuzzi; W. B. Focke; P. Fusco; F. Gargano; D. Gasparrini; E. Giacani; N. Giglietto; T. Glanzman; D. A. Green; I. A. Grenier; S. Guiriec; E. Hays; J. W. Hewitt; A. B. Hill; D. Horan; T. Jogler; G. Jóhannesson; I. Jung-Richardt; S. Kensei; M. Kuss; S. Larsson; L. Latronico; M. Lemoine-Goumard; J. Li; L. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; J. Magill; S. Maldera; A. Manfreda; M. Mayer; M. N. Mazziotta; J. E. McEnery; P. F. Michelson; W. Mitthumsiri; T. Mizuno; M. E. Monzani; A. Morselli; I. V. Moskalenko; M. Negro; Clemson University; Università di Pisa; Kavli Institute for Particle Astrophysics and Cosmology; Istituto Nazionale di Fisica Nucleare, Roma; Universita degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Università degli Studi di Torino; NASA Goddard Space Flight Center; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Deutsche Elektronen-Synchrotron; Consorzio Interuniversitario per la Fisica Spaziale (CIFS); Università degli Studi di Bari; Agenzia Spaziale Italiana; George Mason University, Fairfax Campus; Centre d'Etudes Nucleaires de Bordeaux Gradignan; Osservatorio Astronomico di Roma; Istituto Di Radioastronomia, Bologna; Alma Mater Studiorum Università di Bologna; Università degli Studi di Napoli Federico II; Universita degli Studi di Udine; Instituto de Astronomia y Fisica del Espacio; University of Cambridge; Universite Paris 7- Denis Diderot; University of North Florida; University of Southampton; University Science Institute Reykjavik; Friedrich-Alexander-Universität Erlangen-Nürnberg; Hiroshima University; The Royal Institute of Technology (KTH); Oskar Klein Centre for Cosmoparticle Physics; Universitat Autònoma de Barcelona; Naval Research Laboratory; University of Maryland; Mahidol University; University of Denver; Max Planck Institut fur Physik (Werner-Heisenberg-Institut); University and Research (MIUR); Medizinische Universitat Innsbruck; NYCB Realtime Computing Inc.
    © 2016. The American Astronomical Society. All rights reserved. RCW 86 is a young supernova remnant (SNR) showing a shell-type structure at several wavelengths and is thought to be an efficient cosmic-ray (CR) accelerator. Earlier Fermi Large Area Telescope results reported the detection of γ-ray emission coincident with the position of RCW 86 but its origin (leptonic or hadronic) remained unclear due to the poor statistics. Thanks to 6.5 years of data acquired by the Fermi-LAT and the new event reconstruction Pass 8, we report the significant detection of spatially extended emission coming from RCW 86. The spectrum is described by a power-law function with a very hard photon index in the 0.1-500 GeV range and an energy flux above 100 MeV of erg cm-2 s-1. Gathering all the available multiwavelength (MWL) data, we perform a broadband modeling of the nonthermal emission of RCW 86 to constrain parameters of the nearby medium and bring new hints about the origin of the γ-ray emission. For the whole SNR, the modeling favors a leptonic scenario in the framework of a two-zone model with an average magnetic field of 10.2 ±0.7 μG and a limit on the maximum energy injected into protons of 2 ×1049 erg for a density of 1 cm-3. In addition, parameter values are derived for the north-east and south-west (SW) regions of RCW 86, providing the first indication of a higher magnetic field in the SW region.
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    Erratum: Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data (Astrophysical Journal (2016) 819 (149) DOI: 10.3847/0004-637X/819/2/149)
    (2018-06-10) M. Ackermann; M. Ajello; A. Albert; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; G. A. Caliandro; R. A. Cameron; M. Caragiulo; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; E. Charles; A. Chekhtman; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; J. Conrad; S. Cutini; F. D'Ammando; A. De Angelis; F. De Palma; R. Desiante; S. W. Digel; L. Di Venere; P. S. Drell; C. Favuzzi; S. J. Fegan; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; G. Godfrey; D. Green; I. A. Grenier; S. Guiriec; E. Hays; J. W. Hewitt; D. Horan; G. Jóhannesson; M. Kuss; S. Larsson; L. Latronico; J. Li; L. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; G. M. Madejski; S. Maldera; A. Manfreda; M. Mayer; M. N. Mazziotta; P. F. Michelson; W. Mitthumsiri; T. Mizuno; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; E. Nuss; T. Ohsugi; M. Orienti; E. Orlando; J. F. Ormes; D. Paneque; M. Pesce-Rollins; V. Petrosian; F. Piron; G. Pivato; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; M. Sánchez-Conde; C. Sgrò; E. J. Siskind; F. Spada; G. Spandre; P. Spinelli; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Kavli Institute for Particle Astrophysics and Cosmology; Santa Cruz Institute for Particle Physics; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; NYCB Realtime Computing Inc.; University Science Institute Reykjavik; University of Wisconsin-Madison; Agenzia Spaziale Italiana; Hiroshima University; Deutsches Elektronen-Synchrotron (DESY); Università di Pisa; Stockholms universitet; Alma Mater Studiorum Università di Bologna; Naval Research Laboratory; Clemson University; Università degli Studi di Udine; Osservatorio Astronomico di Roma; Universitat Autònoma de Barcelona; Università degli Studi di Bari; Istituto Nazionale di Fisica Nucleare - INFN; University of Maryland; Università degli Studi di Trieste; George Mason University, Fairfax Campus; Università degli Studi di Napoli Federico II; University of Denver; Mahidol University; Istituto Di Radioastronomia, Bologna; Università degli Studi di Torino; Max Planck Institut für Physik (Werner-Heisenberg-Institut); Medizinische Universitat Innsbruck; University of California, Irvine; NASA Goddard Space Flight Center; Universite Paris 7- Denis Diderot; Università degli Studi di Perugia; The Royal Institute of Technology (KTH); Università degli Studi di Padova; University of North Florida; Oskar Klein Centre for Cosmoparticle Physics; Erlangen Centre for Astroparticle Physics; Consorzio Interuniversitario per la Fisica Spaziale (CIFS)
    © 2018. The American Astronomical Society. All rights reserved. The naming of the sources in Tables 3 and 4 in the Appendix of the published paper did not follow IAU conventions; the corrected nomenclature will enter the NASA Extragalactic Database. Tables 3 and 4 should thus read as follows. (Table Presented).
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    Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-energy Emission from Prompt to Afterglow
    (2020-02-10) M. Ajello; M. Arimoto; M. Axelsson; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; A. Berretta; E. Bissaldi; R. D. Blandford; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; E. Burns; S. Buson; R. A. Cameron; R. Caputo; P. A. Caraveo; E. Cavazzuti; S. Chen; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; D. Costantin; S. Cutini; F. D'Ammando; M. Deklotz; P. De La Torre Luque; F. De Palma; A. Desai; N. Di Lalla; L. Di Venere; F. Fana Dirirsa; S. J. Fegan; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; R. Gill; F. Giordano; M. Giroletti; J. Granot; D. Green; I. A. Grenier; M. H. Grondin; S. Guiriec; E. Hays; D. Horan; G. Jóhannesson; D. Kocevski; M. Kovac'Evic'; M. Kuss; S. Larsson; L. Latronico; M. Lemoine-Goumard; J. Li; I. Liodakis; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; S. Maldera; D. Malyshev; A. Manfreda; G. Martí-Devesa; M. N. Mazziotta; J. E. McEnery; I. Mereu; M. Meyer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; M. Negro; E. Nuss; N. Omodei; M. Orienti; E. Orlando; M. Palatiello; V. S. Paliya; D. Paneque; Z. Pei; M. Persic; M. Pesce-Rollins; V. Petrosian; F. Piron; H. Poon; T. A. Porter; G. Principe; J. L. Racusin; S. Rain; R. Rando; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Laboratoire Univers et Particules de Montpellier; Universite Paris-Saclay; Laboratoire Leprince-Ringuet; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; University Science Institute Reykjavik; Centre d'Etudes Nucléaires de Bordeaux Gradignan; Agenzia Spaziale Italiana; Hiroshima University; Deutsches Elektronen-Synchrotron (DESY); Osservatorio Astronomico di Trieste; Università di Pisa; Stockholms universitet; Naval Research Laboratory; Clemson University; SLAC National Accelerator Laboratory; Kanazawa University; Universitat Autònoma de Barcelona; Università degli Studi di Bari; Open University of Israel; Istituto Nazionale di Fisica Nucleare - INFN; University of Maryland; Università degli Studi di Trieste; Högskolan Dalarna; Mahidol University; Julius-Maximilians-Universität Würzburg; Istituto Di Radioastronomia, Bologna; Università degli Studi di Torino; NASA Marshall Space Flight Center; Max Planck Institute for Physics (Werner Heisenberg Institute); Medizinische Universitat Innsbruck; NASA Goddard Space Flight Center; The George Washington University; Università degli Studi di Perugia; The Royal Institute of Technology (KTH); Friedrich-Alexander-Universität Erlangen-Nürnberg; University of Johannesburg; Università degli Studi di Padova; Stellar Solutions, Inc.
    © 2020. The American Astronomical Society.. We report on the observations of gamma-ray burst (GRB) 190114C by the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory. The prompt gamma-ray emission was detected by the Fermi GRB Monitor (GBM), the Fermi Large Area Telescope (LAT), and the Swift Burst Alert Telescope (BAT) and the long-lived afterglow emission was subsequently observed by the GBM, LAT, Swift X-ray Telescope (XRT), and Swift UV Optical Telescope. The early-time observations reveal multiple emission components that evolve independently, with a delayed power-law component that exhibits significant spectral attenuation above 40 MeV in the first few seconds of the burst. This power-law component transitions to a harder spectrum that is consistent with the afterglow emission observed by the XRT at later times. This afterglow component is clearly identifiable in the GBM and BAT light curves as a slowly fading emission component on which the rest of the prompt emission is superimposed. As a result, we are able to observe the transition from internal-shock- to external-shock-dominated emission. We find that the temporal and spectral evolution of the broadband afterglow emission can be well modeled as synchrotron emission from a forward shock propagating into a wind-like circumstellar environment. We estimate the initial bulk Lorentz factor using the observed high-energy spectral cutoff. Considering the onset of the afterglow component, we constrain the deceleration radius at which this forward shock begins to radiate in order to estimate the maximum synchrotron energy as a function of time. We find that even in the LAT energy range, there exist high-energy photons that are in tension with the theoretical maximum energy that can be achieved through synchrotron emission from a shock. These violations of the maximum synchrotron energy are further compounded by the detection of very high-energy (VHE) emission above 300 GeV by MAGIC concurrent with our observations. We conclude that the observations of VHE photons from GRB 190114C necessitates either an additional emission mechanism at very high energies that is hidden in the synchrotron component in the LAT energy range, an acceleration mechanism that imparts energy to the particles at a rate that is faster than the electron synchrotron energy-loss rate, or revisions of the fundamental assumptions used in estimating the maximum photon energy attainable through the synchrotron process.
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    Fermi Large Area Telescope Performance after 10 Years of Operation
    (2021-09-01) M. Ajello; W. B. Atwood; M. Axelsson; R. Bagagli; M. Bagni; L. Baldini; D. Bastieri; F. Bellardi; R. Bellazzini; E. Bissaldi; E. D. Bloom; R. Bonino; J. Bregeon; A. Brez; P. Bruel; R. Buehler; S. Buson; R. A. Cameron; P. A. Caraveo; E. Cavazzuti; M. Ceccanti; S. Chen; C. C. Cheung; S. Ciprini; I. Cognard; J. Cohen-Tanugi; S. Cutini; F. D'Ammando; P. De La Torre Luque; F. De Palma; S. W. Digel; F. Dirirsa; N. Di Lalla; L. Di Venere; A. Domínguez; D. Fabiani; E. C. Ferrara; A. Fiori; G. Foglia; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; M. Giroletti; T. Glanzman; D. Green; S. Griffin; M. H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; M. Gustafsson; E. Hays; D. Horan; G. Jóhannesson; T. J. Johnson; T. Kamae; M. Kerr; M. Kuss; S. Larsson; L. Latronico; M. Lemoine-Goumard; J. Li; I. Liodakis; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; S. Maldera; A. Manfreda; G. Martí-Devesa; M. N. Mazziotta; N. Menon; I. Mereu; M. Meyer; P. F. Michelson; M. Minuti; W. Mitthumsiri; T. Mizuno; M. Mongelli; M. E. Monzani; I. V. Moskalenko; M. Negro; E. Nuss; R. Ojha; M. Orienti; E. Orlando; A. Paccagnella; V. S. Paliya; D. Paneque; Z. Pei; J. S. Perkins; M. Pesce-Rollins; M. Pinchera; F. Piron; H. Poon; T. A. Porter; R. Primavera; G. Principe; J. L. Racusin; Oskar Klein Centre; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Lecce; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Laboratoire Univers et Particules de Montpellier; Santa Cruz Institute for Particle Physics; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Raunvísindastofnun Háskólans; Laboratoire de Physique des 2 infinis de Bordeaux; Agenzia Spaziale Italiana; Georg-August-Universität Göttingen; Hiroshima University; Deutsches Elektronen-Synchrotron (DESY); Universite d'Orleans; Università di Pisa; Stockholms universitet; Politecnico di Bari; Universidad Complutense de Madrid; Naval Research Laboratory; Clemson University; Laboratoire de Physique Subatomique et de Cosmologie de Grenoble; SLAC National Accelerator Laboratory; The University of Tokyo; University of Maryland, Baltimore County (UMBC); Universita del Salento; University of Maryland, College Park; Université Savoie Mont Blanc; INSU - Institut National des Sciences de l'Univers; Università degli Studi di Trieste; George Mason University; Högskolan Dalarna; École polytechnique; Mahidol University; Julius-Maximilians-Universität Würzburg; Istituto Di Radioastronomia, Bologna; Università degli Studi di Torino; Universität Innsbruck; Max Planck Institute for Physics (Werner Heisenberg Institute); Turun yliopisto; NASA Goddard Space Flight Center; The George Washington University; Università degli Studi di Perugia; The Royal Institute of Technology (KTH); Friedrich-Alexander-Universität Erlangen-Nürnberg; Università degli Studi di Padova
    The Large Area Telescope (LAT), the primary instrument for the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the energy range from 30 MeV to more than 300 GeV. We describe the performance of the instrument at the 10 yr milestone. LAT performance remains well within the specifications defined during the planning phase, validating the design choices and supporting the compelling case to extend the duration of the Fermi mission. The details provided here will be useful when designing the next generation of high-energy gamma-ray observatories.
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    FERMI-LAT OBSERVATIONS of HIGH-ENERGY γ-RAY EMISSION TOWARD the GALACTIC CENTER
    (2016-03-01) M. Ajello; A. Albert; W. B. Atwood; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; T. J. Brandt; J. Bregeon; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; R. Caputo; M. Caragiulo; P. A. Caraveo; C. Cecchi; A. Chekhtman; J. Chiang; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; S. Cutini; F. D'Ammando; A. De Angelis; F. De Palma; R. Desiante; L. Di Venere; P. S. Drell; C. Favuzzi; E. C. Ferrara; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; P. Giommi; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; G. A. Gomez-Vargas; I. A. Grenier; S. Guiriec; M. Gustafsson; A. K. Harding; J. W. Hewitt; A. B. Hill; D. Horan; T. Jogler; G. Jóhannesson; A. S. Johnson; T. Kamae; C. Karwin; J. Knödlseder; M. Kuss; S. Larsson; L. Latronico; J. Li; L. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; Clemson University; Kavli Institute for Particle Astrophysics and Cosmology; Santa Cruz Institute for Particle Physics; Istituto Nazionale di Fisica Nucleare, Roma; Universita degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; University of Wisconsin Madison; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Università degli Studi di Torino; NASA Goddard Space Flight Center; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Deutsche Elektronen-Synchrotron; Consorzio Interuniversitario per la Fisica Spaziale (CIFS); INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Universita degli Studi di Perugia; George Mason University, Fairfax Campus; Agenzia Spaziale Italiana; Osservatorio Astronomico di Roma; Sonoma State University; Stockholms universitet; Oskar Klein Centre for Cosmoparticle Physics; Kungl. Vetenskapsakademien; Istituto Di Radioastronomia, Bologna; Alma Mater Studiorum Università di Bologna; Universita degli Studi di Udine; Università degli Studi di Napoli Federico II; Università degli Studi di Bari; Pontificia Universidad Católica de Chile; Institut de Recherche sur les Lois Fondamentales de l'Univers; Universität Göttingen; University of North Florida; University of Southampton; University Science Institute Reykjavik; University of Tokyo; University of California, Irvine; CNRS Centre National de la Recherche Scientifique; Universite de Toulouse; The Royal Institute of Technology (KTH); Universitat Autònoma de Barcelona; Naval Research Laboratory; University of Maryland; Mahidol University; Hiroshima University; University of Denver; Max Planck Institut fur Physik (Werner-Heisenberg-Institut); The University of Hong Kong; Medizinische Universitat Innsbruck
    © 2016. The American Astronomical Society. All rights reserved. The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission toward the Galactic center (GC) in high-energy γ-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1-100 GeV from a 15° × 15° region about the direction of the GC. Specialized interstellar emission models (IEMs) are constructed to enable the separation of the γ-ray emissions produced by cosmic ray particles interacting with the interstellar gas and radiation fields in the Milky Way into that from the inner ∼1 kpc surrounding the GC, and that from the rest of the Galaxy. A catalog of point sources for the 15° × 15° region is self-consistently constructed using these IEMs: the First Fermi-LAT Inner Galaxy Point Source Catalog (1FIG). The spatial locations, fluxes, and spectral properties of the 1FIG sources are presented, and compared with γ-ray point sources over the same region taken from existing catalogs. After subtracting the interstellar emission and point-source contributions a residual is found. If templates that peak toward the GC are used to model the positive residual the agreement with the data improves, but none of the additional templates tried account for all of its spatial structure. The spectrum of the positive residual modeled with these templates has a strong dependence on the choice of IEM.
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    Gamma-Ray Blazars within the First 2 Billion Years
    (2017-03-01) M. Ackermann; M. Ajello; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; J. Becerra Gonzalez; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; S. Buson; R. A. Cameron; M. Caragiulo; P. A. Caraveo; E. Cavazzuti; C. Cecchi; C. C. Cheung; J. Chiang; G. Chiaro; S. Ciprini; J. Conrad; D. Costantin; F. Costanza; S. Cutini; F. D'Ammando; F. De Palma; R. Desiante; S. W. Digel; N. Di Lalla; M. Di Mauro; L. Di Venere; A. Domínguez; P. S. Drell; C. Favuzzi; S. J. Fegan; E. C. Ferrara; J. Finke; W. B. Focke; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; D. Green; I. A. Grenier; L. Guillemot; S. Guiriec; D. H. Hartmann; E. Hays; D. Horan; T. Jogler; G. Jóhannesson; A. S. Johnson; M. Kuss; G. La Mura; S. Larsson; L. Latronico; J. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; J. D. Magill; S. Maldera; A. Manfreda; L. Marcotulli; M. N. Mazziotta; Deutsche Elektronen-Synchrotron; Clemson University; Università di Pisa; Universite Paris 7- Denis Diderot; Istituto Nazionale di Fisica Nucleare, Roma; Università degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; NASA Goddard Space Flight Center; University of Maryland; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Kavli Institute for Particle Astrophysics and Cosmology; Università degli Studi di Torino; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Università degli Studi di Bari; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Agenzia Spaziale Italiana; Università degli Studi di Perugia; Naval Research Laboratory; Stockholms universitet; Oskar Klein Centre for Cosmoparticle Physics; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna; Alma Mater Studiorum Università di Bologna; Università degli Studi di Napoli Federico II; Università degli Studi di Udine; Hiroshima University; Erlangen Centre for Astroparticle Physics; Universite d'Orleans; Institut National des Sciences de l'Univers; Friedrich-Alexander-Universität Erlangen-Nürnberg; University Science Institute Reykjavik; The Royal Institute of Technology (KTH); Universitat Autònoma de Barcelona; Mahidol University; University of Denver; Max Planck Institut für Physik (Werner-Heisenberg-Institut); Osservatorio Astronomico di Trieste
    © 2017. The American Astronomical Society. All rights reserved. The detection of high-redshift (z > 3) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain the space density of heavy black holes in the early universe. Here, we report the first detection with the Fermi-Large Area Telescope of five γ-ray-emitting blazars beyond z = 3.1, more distant than any blazars previously detected in γ-rays. Among these five objects, NVSS J151002+570243 is now the most distant known γ-ray-emitting blazar at z = 4.31. These objects have steeply falling γ-ray spectral energy distributions (SEDs), and those that have been observed in X-rays have a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance (ratio of the inverse Compton to synchrotron peak luminosities) is also very large (>20). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes (MBH ∼ 10 8-10 Mo ). We find that, at z ≈ 4, the space density of >109 Mo black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early universe.
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    Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope
    (2018-04-10) M. Ackermann; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; R. Bellazzini; B. Berenji; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; R. A. Cameron; R. Caputo; P. A. Caraveo; E. Cavazzuti; E. Charles; A. Chekhtman; C. C. Cheung; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; J. Conrad; D. Costantin; F. D'Ammando; F. De Palma; S. W. Digel; N. Di Lalla; M. Di Mauro; L. Di Venere; C. Favuzzi; S. J. Fegan; W. B. Focke; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; D. Green; I. A. Grenier; L. Guillemot; S. Guiriec; D. Horan; G. Jóhannesson; C. Johnson; S. Kensei; D. Kocevski; M. Kuss; S. Larsson; L. Latronico; J. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; J. D. Magill; S. Maldera; D. Malyshev; A. Manfreda; M. N. Mazziotta; J. E. McEnery; M. Meyer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; M. Negro; E. Nuss; R. Ojha; N. Omodei; M. Orienti; E. Orlando; J. F. Ormes; M. Palatiello; V. S. Paliya; D. Paneque; M. Persic; M. Pesce-Rollins; F. Piron; G. Principe; S. Rainò; R. Rando; M. Razzano; S. Razzaque; A. Reimer; O. Reimer; S. Ritz; M. Sánchez-Conde; C. Sgrò; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste; Istituto Nazionale di Fisica Nucleare, Sezione di Perugia; Istituto Nazionale di Fisica Nucleare, Sezione di Bari; Istituto Nazionale di Fisica Nucleare, Sezione di Torino; Istituto Nazionale di Fisica Nucleare, Sezione di Pisa; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Kavli Institute for Particle Astrophysics and Cosmology; Santa Cruz Institute for Particle Physics; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; University Science Institute Reykjavik; Agenzia Spaziale Italiana; Hiroshima University; California State University, Los Angeles; Deutsches Elektronen-Synchrotron (DESY); Osservatorio Astronomico di Trieste; Universite d'Orleans; Università di Pisa; Stockholms universitet; Alma Mater Studiorum Università di Bologna; Naval Research Laboratory; Universidad Autónoma de Madrid; Clemson University; Nordisk Institut for Teoretisk Atomtysik; Universitat Autònoma de Barcelona; Università degli Studi di Bari; Istituto Nazionale di Fisica Nucleare - INFN; University of Maryland; Institut National des Sciences de l'Univers; Università degli Studi di Trieste; George Mason University, Fairfax Campus; Università degli Studi di Napoli Federico II; University of Denver; Mahidol University; Università degli Studi di Torino; Max Planck Institut für Physik (Werner-Heisenberg-Institut); Medizinische Universitat Innsbruck; NASA Goddard Space Flight Center; Universite Paris 7- Denis Diderot; George Washington University; The Royal Institute of Technology (KTH); Friedrich-Alexander-Universität Erlangen-Nürnberg; University of Johannesburg; Università degli Studi di Padova; Oskar Klein Centre for Cosmoparticle Physics
    © 2018. The American Astronomical Society. All rights reserved. Black holes with masses below approximately 1015 g are expected to emit gamma-rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black holes with these masses cannot be formed as a result of stellar evolution, they may have formed in the early universe and are therefore called primordial black holes (PBHs). Previous searches for PBHs have focused on either short-timescale bursts or the contribution of PBHs to the isotropic gamma-ray emission. We show that, in cases of individual PBHs, the Fermi-LAT is most sensitive to PBHs with temperatures above approximately 16 GeV and masses 6 ×1011 g, which it can detect out to a distance of about 0.03 pc. These PBHs have a remaining lifetime of months to years at the start of the Fermi mission. They would appear as potentially moving point sources with gamma-ray emission that become spectrally harder and brighter with time until the PBH completely evaporates. In this paper, we develop a new algorithm to detect the proper motion of gamma-ray point sources, and apply it to 318 unassociated point sources at a high galactic latitude in the third Fermi-LAT source catalog. None of the unassociated point sources with spectra consistent with PBH evaporation show significant proper motion. Using the nondetection of PBH candidates, we derive a 99% confidence limit on the PBH evaporation rate in the vicinity of Earth, PPBH < 7.2 × 103 pc-3 yr-1. This limit is similar to the limits obtained with ground-based gamma-ray observatories.
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    SEARCH for GAMMA-RAY EMISSION from the COMA CLUSTER with SIX YEARS of FERMI-LAT DATA
    (2016-03-10) M. Ackermann; M. Ajello; A. Albert; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; G. A. Caliandro; R. A. Cameron; M. Caragiulo; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; E. Charles; A. Chekhtman; G. Chiaro; S. Ciprini; J. Cohen-Tanugi; J. Conrad; S. Cutini; F. D'Ammando; A. De Angelis; F. De Palma; R. Desiante; S. W. Digel; L. Di Venere; P. S. Drell; C. Favuzzi; S. J. Fegan; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; F. Giordano; M. Giroletti; G. Godfrey; D. Green; I. A. Grenier; S. Guiriec; E. Hays; J. W. Hewitt; D. Horan; G. Jóhannesson; M. Kuss; S. Larsson; L. Latronico; J. Li; L. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; G. M. Madejski; S. Maldera; A. Manfreda; M. Mayer; M. N. Mazziotta; P. F. Michelson; W. Mitthumsiri; T. Mizuno; Deutsche Elektronen-Synchrotron; Clemson University; Kavli Institute for Particle Astrophysics and Cosmology; Santa Cruz Institute for Particle Physics; Università di Pisa; Universite Paris 7- Denis Diderot; Istituto Nazionale di Fisica Nucleare, Roma; Universita degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; University of Wisconsin Madison; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Università degli Studi di Torino; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Consorzio Interuniversitario per la Fisica Spaziale (CIFS); Università degli Studi di Bari; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Agenzia Spaziale Italiana; Universita degli Studi di Perugia; George Mason University, Fairfax Campus; Stockholms universitet; Oskar Klein Centre for Cosmoparticle Physics; Osservatorio Astronomico di Roma; Istituto Di Radioastronomia, Bologna; Alma Mater Studiorum Università di Bologna; Universita degli Studi di Udine; Università degli Studi di Napoli Federico II; Hiroshima University; Erlangen Centre for Astroparticle Physics; University of Maryland; NASA Goddard Space Flight Center; University of North Florida; University Science Institute Reykjavik; The Royal Institute of Technology (KTH); Universitat Autònoma de Barcelona; Naval Research Laboratory; Mahidol University; University of California, Irvine; University of Denver; Max Planck Institut fur Physik (Werner-Heisenberg-Institut); Medizinische Universitat Innsbruck; NYCB Realtime Computing Inc.
    © 2016. The American Astronomical Society. All rights reserved.. We present results from γ-ray observations of the Coma cluster incorporating six years of Fermi-LAT data and the newly released "Pass 8" event-level analysis. Our analysis of the region reveals low-significance residual structures within the virial radius of the cluster that are too faint for a detailed investigation with the current data. Using a likelihood approach that is free of assumptions on the spectral shape we derive upper limits on the γ-ray flux that is expected from energetic particle interactions in the cluster. We also consider a benchmark spatial and spectral template motivated by models in which the observed radio halo is mostly emission by secondary electrons. In this case, the median expected and observed upper limits for the flux above 100 are 1.7 times;10-9 ph cm-2 s-1 and 5.2 times;10-9 ph cm-2 s-1 respectively (the latter corresponds to residual emission at the level of 1.8σ). These bounds are comparable to or higher than predicted levels of hadronic gamma-ray emission in cosmic-ray (CR) models with or without reacceleration of secondary electrons, although direct comparisons are sensitive to assumptions regarding the origin and propagation mode of CRs and magnetic field properties. The minimal expected γ-ray flux from radio and star-forming galaxies within the Coma cluster is roughly an order of magnitude below the median sensitivity of our analysis.
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    The Second Catalog of Flaring Gamma-Ray Sources from the Fermi All-sky Variability Analysis
    (2017-09-01) S. Abdollahi; M. Ackermann; M. Ajello; A. Albert; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; J. Becerra Gonzalez; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; S. Buson; R. A. Cameron; M. Caragiulo; P. A. Caraveo; E. Cavazzuti; C. Cecchi; A. Chekhtman; C. C. Cheung; G. Chiaro; S. Ciprini; J. Conrad; D. Costantin; F. Costanza; S. Cutini; F. D'Ammando; F. De Palma; A. Desai; R. Desiante; S. W. Digel; N. Di Lalla; M. Di Mauro; L. Di Venere; B. Donaggio; P. S. Drell; C. Favuzzi; S. J. Fegan; E. C. Ferrara; W. B. Focke; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Giglietto; M. Giomi; F. Giordano; M. Giroletti; T. Glanzman; D. Green; I. A. Grenier; J. E. Grove; L. Guillemot; S. Guiriec; E. Hays; D. Horan; T. Jogler; G. Jóhannesson; A. S. Johnson; D. Kocevski; M. Kuss; G. La Mura; S. Larsson; L. Latronico; J. Li; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; Hiroshima University; Deutsche Elektronen-Synchrotron; Clemson University; Los Alamos National Laboratory; Università di Pisa; Universite Paris 7- Denis Diderot; Istituto Nazionale di Fisica Nucleare, Roma; Università degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Università degli Studi di Padova; NASA Goddard Space Flight Center; University of Maryland; Istituto Nazionale Di Fisica Nucleare, Sezione di Pisa; Kavli Institute for Particle Astrophysics and Cosmology; Università degli Studi di Torino; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Università degli Studi di Bari; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Agenzia Spaziale Italiana; Università degli Studi di Perugia; George Mason University, Fairfax Campus; Naval Research Laboratory; Stockholms universitet; Oskar Klein Centre for Cosmoparticle Physics; INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna; Alma Mater Studiorum Università di Bologna; Università degli Studi di Napoli Federico II; Università degli Studi di Udine; Erlangen Centre for Astroparticle Physics; Universite d'Orleans; Institut National des Sciences de l'Univers; Friedrich-Alexander-Universität Erlangen-Nürnberg; University Science Institute Reykjavik; The Royal Institute of Technology (KTH); Universitat Autònoma de Barcelona; Mahidol University; Max Planck Institut für Physik (Werner-Heisenberg-Institut); Osservatorio Astronomico di Trieste
    © 2017. The American Astronomical Society. All rights reserved. We present the second catalog of flaring gamma-ray sources (2FAV) detected with the Fermi All-sky Variability Analysis (FAVA), a tool that blindly searches for transients over the entire sky observed by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. With respect to the first FAVA catalog, this catalog benefits from a larger data set, the latest LAT data release (Pass 8), as well as from an improved analysis that includes likelihood techniques for a more precise localization of the transients. Applying this analysis to the first 7.4 years of Fermi observations, and in two separate energy bands 0.1-0.8 GeV and 0.8-300 GeV, a total of 4547 flares were detected with significance greater than 6σ(before trials), on the timescale of one week. Through spatial clustering of these flares, 518 variable gamma-ray sources were identified. Based on positional coincidence, likely counterparts have been found for 441 sources, mostly among the blazar class of active galactic nuclei. For 77 2FAV sources, no likely gamma-ray counterpart has been found. For each source in the catalog, we provide the time, location, and spectrum of each flaring episode. Studying the spectra of the flares, we observe a harder-when-brighter behavior for flares associated with blazars, with the exception of BL Lac flares detected in the low-energy band. The photon indexes of the flares are never significantly smaller than 1.5. For a leptonic model, and under the assumption of isotropy, this limit suggests that the spectrum of freshly accelerated electrons is never harder than P ∼ 2.
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    The spectrum and morphology of the Fermi bubbles
    (2014-09-20) M. Ackermann; A. Albert; W. B. Atwood; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; E. Bottacini; T. J. Brandt; J. Bregeon; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; M. Caragiulo; P. A. Caraveo; E. Cavazzuti; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; G. Chiaro; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; S. Cutini; F. D'Ammando; A. De Angelis; F. De Palma; C. D. Dermer; S. W. Digel; L. Di Venere; E. Do Couto E Silva; P. S. Drell; C. Favuzzi; E. C. Ferrara; W. B. Focke; A. Franckowiak; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; S. Germani; N. Giglietto; F. Giordano; M. Giroletti; G. Godfrey; G. A. Gomez-Vargas; I. A. Grenier; S. Guiriec; D. Hadasch; A. K. Harding; E. Hays; J. W. Hewitt; X. Hou; T. Jogler; G. Jóhannesson; A. S. Johnson; W. N. Johnson; T. Kamae; J. Kataoka; J. Knödlseder; D. Kocevski; M. Kuss; S. Larsson; L. Latronico; F. Longo; F. Loparco; M. N. Lovellette; Deutsche Elektronen-Synchrotron; Kavli Institute for Particle Astrophysics and Cosmology; Santa Cruz Institute for Particle Physics; Istituto Nazionale di Fisica Nucleare, Roma; Institut de Recherche sur les Lois Fondamentales de l'Univers; Universita degli Studi di Trieste; Istituto Nazionale Di Fisica Nucleare, Sezione di Padova; Universita degli Studi di Padova; NASA Goddard Space Flight Center; Laboratoire Univers et Particules de Montpellier; Laboratoire Leprince-Ringuet; Consorzio Interuniversitario per la Fisica Spaziale (CIFS); INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan; Agenzia Spaziale Italiana; Universita degli Studi di Perugia; George Mason University, Fairfax Campus; Osservatorio Astronomico di Roma; Stockholms universitet; Oskar Klein Centre for Cosmoparticle Physics; Kungl. Vetenskapsakademien; Istituto Di Radioastronomia, Bologna; Alma Mater Studiorum Universita di Bologna; Universita degli Studi di Udine; Naval Research Laboratory; Universita degli Studi di Bari; Hiroshima University; Pontificia Universidad Catolica de Chile; Medizinische Universitat Innsbruck; University of Maryland, Baltimore County; Centre d'Etudes Nucleaires de Bordeaux Gradignan; University Science Institute Reykjavik; Waseda University; CNRS Centre National de la Recherche Scientifique; Universite de Toulouse; Yale University; University of Maryland; Mahidol University; University of California, Irvine; University of Denver; Max Planck Institut fur Physik (Werner-Heisenberg-Institut)
    © 2014. The American Astronomical Society. All rights reserved. The Fermi bubbles are two large structures in the gamma-ray sky extending to 55° above and below the Galactic center. We analyze 50 months of Fermi Large Area Telescope data between 100 MeV and 500 GeV above 10° in Galactic latitude to derive the spectrum and morphology of the Fermi bubbles. We thoroughly explore the systematic uncertainties that arise when modeling the Galactic diffuse emission through two separate approaches. The gamma-ray spectrum is well described by either a log parabola or a power law with an exponential cutoff. We exclude a simple power law with more than 7σ significance. The power law with an exponential cutoff has an index of 1.9 ± 0.2 and a cutoff energy of 110 ± 50 GeV. We find that the gamma-ray luminosity of the bubbles is erg s-1. We confirm a significant enhancement of gamma-ray emission in the southeastern part of the bubbles, but we do not find significant evidence for a jet. No significant variation of the spectrum across the bubbles is detected. The width of the boundary of the bubbles is estimated to be deg. Both inverse Compton (IC) models and hadronic models including IC emission from secondary leptons fit the gamma-ray data well. In the IC scenario, synchrotron emission from the same population of electrons can also explain the WMAP and Planck microwave haze with a magnetic field between 5 and 20 μG.