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Title: Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 [Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273]

Here, we present a γ-ray photon flux and spectral variability study of the flat-spectrum radio quasar 3C 273 over a rapid flaring activity period between September 2009 to April 2010. Five major flares were observed in the source during this period. The most rapid flare observed in the source has a flux doubling time of 1.1 hr. The rapid γ-ray flares allow us to constrain the location and size of the γ-ray emission region in the source. The γγ-opacity constrains the Doppler factor δ γ ≥ 10 for the highest energy (15 GeV) photon observed by the Fermi-Large Area Telescope (LAT). Causality arguments constrain the size of the emission region to 1.6 × 10 15 cm. The γ-ray spectra measured over this period show clear deviations from a simple power law with a break in the 1–2 GeV energy range. We discuss possible explanations for the origin of the γ-ray spectral breaks. Our study suggests that the γ-ray emission region in 3C 273 is located within the broad line region (< 1.6 pc). As a result, the spectral behavior and temporal characteristics of the individual flares indicate the presence of multiple shock scenarios at the base of the jet.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Max-Planck-Institut fur Radioastronomie (MPIfR), Bonn (Germany)
  2. Centre d'Etudes Nucleaires de Bordeaux Gradignan, Gradignan (France)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 557; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma rays: galaxies; galaxies: active; quasars: individual: 3C 273
OSTI Identifier:
1356560

Rani, B., Lott, B., Krichbaum, T. P., Fuhrmann, L., and Zensus, J. A.. Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 [Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273]. United States: N. p., Web. doi:10.1051/0004-6361/201321440.
Rani, B., Lott, B., Krichbaum, T. P., Fuhrmann, L., & Zensus, J. A.. Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 [Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273]. United States. doi:10.1051/0004-6361/201321440.
Rani, B., Lott, B., Krichbaum, T. P., Fuhrmann, L., and Zensus, J. A.. 2013. "Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 [Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273]". United States. doi:10.1051/0004-6361/201321440. https://www.osti.gov/servlets/purl/1356560.
@article{osti_1356560,
title = {Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 [Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273]},
author = {Rani, B. and Lott, B. and Krichbaum, T. P. and Fuhrmann, L. and Zensus, J. A.},
abstractNote = {Here, we present a γ-ray photon flux and spectral variability study of the flat-spectrum radio quasar 3C 273 over a rapid flaring activity period between September 2009 to April 2010. Five major flares were observed in the source during this period. The most rapid flare observed in the source has a flux doubling time of 1.1 hr. The rapid γ-ray flares allow us to constrain the location and size of the γ-ray emission region in the source. The γγ-opacity constrains the Doppler factor δγ ≥ 10 for the highest energy (15 GeV) photon observed by the Fermi-Large Area Telescope (LAT). Causality arguments constrain the size of the emission region to 1.6 × 1015 cm. The γ-ray spectra measured over this period show clear deviations from a simple power law with a break in the 1–2 GeV energy range. We discuss possible explanations for the origin of the γ-ray spectral breaks. Our study suggests that the γ-ray emission region in 3C 273 is located within the broad line region (< 1.6 pc). As a result, the spectral behavior and temporal characteristics of the individual flares indicate the presence of multiple shock scenarios at the base of the jet.},
doi = {10.1051/0004-6361/201321440},
journal = {Astronomy and Astrophysics},
number = ,
volume = 557,
place = {United States},
year = {2013},
month = {9}
}