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Title: SPECTRAL ANALYSIS OF FERMI -LAT BLAZARS ABOVE 50 GEV

Abstract

We present an analysis of the intrinsic (unattenuated by the extragalactic background light, EBL) power-law spectral indices of 128 extragalactic sources detected up to z ~ 2 with the Fermi-Large Area Telescope (LAT) at very high energies (VHEs, E ≥50 GeV). The median of the intrinsic index distribution is 2.20 (versus 2.54 for the observed distribution). We also analyze the observed spectral breaks (i.e., the difference between the VHE and high energy, HE, 100 MeV ≤ E ≤ 300 GeV, spectral indices). The Fermi-LAT has now provided a large sample of sources detected both at VHE and HE with comparable exposure that allows us to test models of extragalactic γ-ray photon propagation. We find that our data are compatible with simulations that include intrinsic blazar curvature and EBL attenuation. There is also no evidence of evolution with redshift of the physics that drives the photon emission in high-frequency synchrotron peak (HSP) blazars. This makes HSP blazars excellent probes of the EBL.

Authors:
 [1]; ORCiD logo [2]
  1. Clemson Univ., SC (United States); Univ. Complutense Madrid (Spain)
  2. Clemson Univ., SC (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1354852
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 813; Journal Issue: 2; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Domínguez, Alberto, and Ajello, Marco. SPECTRAL ANALYSIS OF FERMI -LAT BLAZARS ABOVE 50 GEV. United States: N. p., 2015. Web. doi:10.1088/2041-8205/813/2/L34.
Domínguez, Alberto, & Ajello, Marco. SPECTRAL ANALYSIS OF FERMI -LAT BLAZARS ABOVE 50 GEV. United States. doi:10.1088/2041-8205/813/2/L34.
Domínguez, Alberto, and Ajello, Marco. Wed . "SPECTRAL ANALYSIS OF FERMI -LAT BLAZARS ABOVE 50 GEV". United States. doi:10.1088/2041-8205/813/2/L34. https://www.osti.gov/servlets/purl/1354852.
@article{osti_1354852,
title = {SPECTRAL ANALYSIS OF FERMI -LAT BLAZARS ABOVE 50 GEV},
author = {Domínguez, Alberto and Ajello, Marco},
abstractNote = {We present an analysis of the intrinsic (unattenuated by the extragalactic background light, EBL) power-law spectral indices of 128 extragalactic sources detected up to z ~ 2 with the Fermi-Large Area Telescope (LAT) at very high energies (VHEs, E ≥50 GeV). The median of the intrinsic index distribution is 2.20 (versus 2.54 for the observed distribution). We also analyze the observed spectral breaks (i.e., the difference between the VHE and high energy, HE, 100 MeV ≤ E ≤ 300 GeV, spectral indices). The Fermi-LAT has now provided a large sample of sources detected both at VHE and HE with comparable exposure that allows us to test models of extragalactic γ-ray photon propagation. We find that our data are compatible with simulations that include intrinsic blazar curvature and EBL attenuation. There is also no evidence of evolution with redshift of the physics that drives the photon emission in high-frequency synchrotron peak (HSP) blazars. This makes HSP blazars excellent probes of the EBL.},
doi = {10.1088/2041-8205/813/2/L34},
journal = {The Astrophysical Journal. Letters},
number = 2,
volume = 813,
place = {United States},
year = {2015},
month = {11}
}

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