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Title: FERMI OBSERVATIONS OF THE VERY HARD GAMMA-RAY BLAZAR PG 1553+113

Abstract

We report the observations of PG 1553+113 during the first approx 200 days of Fermi Gamma-ray Space Telescope science operations, from 2008 August 4 to 2009 February 22 (MJD 54682.7-54884.2). This is the first detailed study of PG 1553+113 in the GeV gamma-ray regime and it allows us to fill a gap of three decades in energy in its spectral energy distribution (SED). We find PG 1553+113 to be a steady source with a hard spectrum that is best fit by a simple power law in the Fermi energy band. We combine the Fermi data with archival radio, optical, X-ray, and very high energy (VHE) gamma-ray data to model its broadband SED and find that a simple, one-zone synchrotron self-Compton model provides a reasonable fit. PG 1553+113 has the softest VHE spectrum of all sources detected in that regime and, out of those with significant detections across the Fermi energy bandpass so far, the hardest spectrum in that energy regime. Thus, it has the largest spectral break of any gamma-ray source studied to date, which could be due to the absorption of the intrinsic gamma-ray spectrum by the extragalactic background light (EBL). Assuming this to be the case, we selectedmore » a model with a low level of EBL and used it to absorb the power-law spectrum from PG 1553+113 measured with Fermi (200 MeV-157 GeV) to find the redshift, which gave the best fit to the measured VHE data (90 GeV-1.1 TeV) for this parameterization of the EBL. We show that this redshift can be considered an upper limit on the distance to PG 1553+113.« less

Authors:
 [1]; ; ; ; ; ;  [2];  [3];  [4]; ; ; ;  [5];  [6];  [7];  [8];  [9];  [10];  [11]
  1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
  2. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  3. Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)
  4. Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden)
  5. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  6. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
  7. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  8. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
  9. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
  10. Dipartimento di Fisica, 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy)
  11. Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)
Publication Date:
OSTI Identifier:
21392416
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 708; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/708/2/1310; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; BL LACERTAE OBJECTS; COSMIC GAMMA SOURCES; ENERGY SPECTRA; GAMMA RADIATION; GAMMA SPECTRA; GEV RANGE; RED SHIFT; TELESCOPES; TEV RANGE; X RADIATION; COSMIC RADIO SOURCES; COSMIC RAY SOURCES; ELECTROMAGNETIC RADIATION; ENERGY RANGE; IONIZING RADIATIONS; RADIATIONS; SORPTION; SPECTRA

Citation Formats

Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Axelsson, M, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, and Burnett, T. H., E-mail: deirdre@llr.in2p3.f, E-mail: dsanchez@llr.in2p3.f, E-mail: deirdre@in2p3.f, E-mail: sanchez@poly.in2p3.f. FERMI OBSERVATIONS OF THE VERY HARD GAMMA-RAY BLAZAR PG 1553+113. United States: N. p., 2010. Web. doi:10.1088/0004-637X/708/2/1310.
Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Axelsson, M, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, & Burnett, T. H., E-mail: deirdre@llr.in2p3.f, E-mail: dsanchez@llr.in2p3.f, E-mail: deirdre@in2p3.f, E-mail: sanchez@poly.in2p3.f. FERMI OBSERVATIONS OF THE VERY HARD GAMMA-RAY BLAZAR PG 1553+113. United States. doi:10.1088/0004-637X/708/2/1310.
Abdo, A A, Ackermann, M, Ajello, M, Bechtol, K, Berenji, B, Bloom, E D, Borgland, A W, Atwood, W B, Axelsson, M, Baldini, L, Bellazzini, R, Bregeon, J, Brez, A, Ballet, J, Barbiellini, G, Bastieri, D, Bonamente, E, Brigida, M, Bruel, P, and Burnett, T. H., E-mail: deirdre@llr.in2p3.f, E-mail: dsanchez@llr.in2p3.f, E-mail: deirdre@in2p3.f, E-mail: sanchez@poly.in2p3.f. Sun . "FERMI OBSERVATIONS OF THE VERY HARD GAMMA-RAY BLAZAR PG 1553+113". United States. doi:10.1088/0004-637X/708/2/1310.
@article{osti_21392416,
title = {FERMI OBSERVATIONS OF THE VERY HARD GAMMA-RAY BLAZAR PG 1553+113},
author = {Abdo, A A and Ackermann, M and Ajello, M and Bechtol, K and Berenji, B and Bloom, E D and Borgland, A W and Atwood, W B and Axelsson, M and Baldini, L and Bellazzini, R and Bregeon, J and Brez, A and Ballet, J and Barbiellini, G and Bastieri, D and Bonamente, E and Brigida, M and Bruel, P and Burnett, T. H., E-mail: deirdre@llr.in2p3.f, E-mail: dsanchez@llr.in2p3.f, E-mail: deirdre@in2p3.f, E-mail: sanchez@poly.in2p3.f},
abstractNote = {We report the observations of PG 1553+113 during the first approx 200 days of Fermi Gamma-ray Space Telescope science operations, from 2008 August 4 to 2009 February 22 (MJD 54682.7-54884.2). This is the first detailed study of PG 1553+113 in the GeV gamma-ray regime and it allows us to fill a gap of three decades in energy in its spectral energy distribution (SED). We find PG 1553+113 to be a steady source with a hard spectrum that is best fit by a simple power law in the Fermi energy band. We combine the Fermi data with archival radio, optical, X-ray, and very high energy (VHE) gamma-ray data to model its broadband SED and find that a simple, one-zone synchrotron self-Compton model provides a reasonable fit. PG 1553+113 has the softest VHE spectrum of all sources detected in that regime and, out of those with significant detections across the Fermi energy bandpass so far, the hardest spectrum in that energy regime. Thus, it has the largest spectral break of any gamma-ray source studied to date, which could be due to the absorption of the intrinsic gamma-ray spectrum by the extragalactic background light (EBL). Assuming this to be the case, we selected a model with a low level of EBL and used it to absorb the power-law spectrum from PG 1553+113 measured with Fermi (200 MeV-157 GeV) to find the redshift, which gave the best fit to the measured VHE data (90 GeV-1.1 TeV) for this parameterization of the EBL. We show that this redshift can be considered an upper limit on the distance to PG 1553+113.},
doi = {10.1088/0004-637X/708/2/1310},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 708,
place = {United States},
year = {2010},
month = {1}
}

Works referencing / citing this record:

Probing the very high energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes
journal, May 2015

  • Aleksić, J.; Ansoldi, S.; Antonelli, L. A.
  • Monthly Notices of the Royal Astronomical Society, Vol. 450, Issue 4
  • DOI: 10.1093/mnras/stv811

Ten years of AGILE: the mission and scientific highlights
journal, September 2019


Ten years of AGILE: the mission and scientific highlights
journal, September 2019


Probing the very high energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes
journal, May 2015

  • Aleksić, J.; Ansoldi, S.; Antonelli, L. A.
  • Monthly Notices of the Royal Astronomical Society, Vol. 450, Issue 4
  • DOI: 10.1093/mnras/stv811

New Hard-TeV Extreme Blazars Detected with the MAGIC Telescopes
journal, February 2020

  • Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.
  • The Astrophysical Journal Supplement Series, Vol. 247, Issue 1
  • DOI: 10.3847/1538-4365/ab5b98