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Title: SWIFT BURST ALERT TELESCOPE, FERMI LARGE AREA TELESCOPE, AND THE BLAZAR SEQUENCE

Abstract

Using public Fermi Large Area Telescope (LAT) and Swift Burst Alert Telescope observations, we constructed the first sample of blazars selected at both hard X-rays and gamma rays. Studying its spectral properties, we find a luminosity dependence of the spectral slopes at both energies. Specifically, luminous blazars, generally classified as flat spectrum radio quasars, have hard continua in the medium-hard X-ray range but soft continua in the LAT gamma-ray range (photon indices GAMMA{sub X} {approx}< 2 and GAMMA{sub G} {approx}> 2), while lower luminosity blazars, classified as BL Lacs, have opposite behavior, i.e., soft X-ray and hard gamma-ray continua (GAMMA{sub X} {approx}> 2.4 and GAMMA{sub G} < 2). The trends are confirmed by detailed Monte Carlo simulations explicitly taking into account the observational biases of both instruments. Our results support the so-called blazar sequence which was originally based on radio samples of blazars and radio luminosities. We also argue that the X-ray-to-gamma-ray continua of blazars may provide independent insights into the physical conditions around the jet, complementing/superseding the ambiguities of the traditional classification based on optical properties.

Authors:
;  [1]; ; ; ; ; ; ;  [2];  [3];  [4]
  1. NASA/GSFC, Code 662, Greenbelt, MD 20771 (United States)
  2. NASA/GSFC, Code 661, Greenbelt, MD 20771 (United States)
  3. SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
  4. INAF-Osservatorio Astronomico di Brera, V. Brera 28, I-20100 Milano (Italy)
Publication Date:
OSTI Identifier:
21394534
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 710; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/710/1/24; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; CLASSIFICATION; COMPUTERIZED SIMULATION; COSMIC PHOTONS; GAMMA RADIATION; HARD X RADIATION; LUMINOSITY; MONTE CARLO METHOD; QUASARS; SOFT X RADIATION; TELESCOPES; X-RAY GALAXIES; BOSONS; CALCULATION METHODS; COSMIC RADIATION; COSMIC RADIO SOURCES; COSMIC RAY SOURCES; COSMIC X-RAY SOURCES; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; GALAXIES; IONIZING RADIATIONS; MASSLESS PARTICLES; OPTICAL PROPERTIES; PHOTONS; PHYSICAL PROPERTIES; RADIATIONS; SIMULATION; X RADIATION

Citation Formats

Sambruna, R M, Mushotzky, R F, Donato, D, Tueller, J, Baumgartner, W, Skinner, G, Markwardt, C, Barthelmy, S, Gehrels, N, Ajello, M, and Maraschi, L. SWIFT BURST ALERT TELESCOPE, FERMI LARGE AREA TELESCOPE, AND THE BLAZAR SEQUENCE. United States: N. p., 2010. Web. doi:10.1088/0004-637X/710/1/24.
Sambruna, R M, Mushotzky, R F, Donato, D, Tueller, J, Baumgartner, W, Skinner, G, Markwardt, C, Barthelmy, S, Gehrels, N, Ajello, M, & Maraschi, L. SWIFT BURST ALERT TELESCOPE, FERMI LARGE AREA TELESCOPE, AND THE BLAZAR SEQUENCE. United States. https://doi.org/10.1088/0004-637X/710/1/24
Sambruna, R M, Mushotzky, R F, Donato, D, Tueller, J, Baumgartner, W, Skinner, G, Markwardt, C, Barthelmy, S, Gehrels, N, Ajello, M, and Maraschi, L. 2010. "SWIFT BURST ALERT TELESCOPE, FERMI LARGE AREA TELESCOPE, AND THE BLAZAR SEQUENCE". United States. https://doi.org/10.1088/0004-637X/710/1/24.
@article{osti_21394534,
title = {SWIFT BURST ALERT TELESCOPE, FERMI LARGE AREA TELESCOPE, AND THE BLAZAR SEQUENCE},
author = {Sambruna, R M and Mushotzky, R F and Donato, D and Tueller, J and Baumgartner, W and Skinner, G and Markwardt, C and Barthelmy, S and Gehrels, N and Ajello, M and Maraschi, L},
abstractNote = {Using public Fermi Large Area Telescope (LAT) and Swift Burst Alert Telescope observations, we constructed the first sample of blazars selected at both hard X-rays and gamma rays. Studying its spectral properties, we find a luminosity dependence of the spectral slopes at both energies. Specifically, luminous blazars, generally classified as flat spectrum radio quasars, have hard continua in the medium-hard X-ray range but soft continua in the LAT gamma-ray range (photon indices GAMMA{sub X} {approx}< 2 and GAMMA{sub G} {approx}> 2), while lower luminosity blazars, classified as BL Lacs, have opposite behavior, i.e., soft X-ray and hard gamma-ray continua (GAMMA{sub X} {approx}> 2.4 and GAMMA{sub G} < 2). The trends are confirmed by detailed Monte Carlo simulations explicitly taking into account the observational biases of both instruments. Our results support the so-called blazar sequence which was originally based on radio samples of blazars and radio luminosities. We also argue that the X-ray-to-gamma-ray continua of blazars may provide independent insights into the physical conditions around the jet, complementing/superseding the ambiguities of the traditional classification based on optical properties.},
doi = {10.1088/0004-637X/710/1/24},
url = {https://www.osti.gov/biblio/21394534}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 710,
place = {United States},
year = {Wed Feb 10 00:00:00 EST 2010},
month = {Wed Feb 10 00:00:00 EST 2010}
}