SPECTRAL PROPERTIES OF BRIGHT FERMI-DETECTED BLAZARS IN THE GAMMA-RAY BAND

By A. Abdo, M. Ackermann, M. Ajello, W. Atwood, M. Axelsson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol and 167 more. 2010

160 citations recorded by the source corpus.

The gamma-ray energy spectra of bright blazars of the LAT Bright AGN Sample (LBAS) are investigated using Fermi-LAT data. Spectral properties (hardness, curvature, and variability) established using a data set accumulated over 6 months of operation are presented and discussed for different blazar classes and subclasses: flat spectrum radio quasars (FSRQs), low-synchrotron peaked BLLacs (LSP-BLLacs), intermediate-synchrotron peaked BLLacs (ISP-BLLacs), and high-synchrotron peaked BLLacs (HSP-BLLacs). The distribution of photon index (Γ, obtained from a power-law fit above 100 MeV) is found to correlate strongly with blazar subclass. The change in spectral index from that averaged over the 6 months observing period is < 0.2–0.3 when the flux varies by about an order of magnitude, with a tendency toward harder spectra when the flux is brighter for FSRQs and LSP-BLLacs. A strong departure from a single power-law spectrum appears to be a common feature for FSRQs. This feature is also present for some high-luminosity LSP-BLLacs, and a small number of ISP-BLLacs. It is absent in all LBAS HSP-BLLacs. For 3C 454.3 and AO 0235+164, the two brightest FSRQ source and LSP-BLLac source, respectively, a broken power law (BPL) gives the most acceptable of power law, BPL, and curved forms. The consequences of these findings are discussed.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/9a0c3fe4c4fea9e747b2b2ed414d4b2e5c2cfb70

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Citations in the corpus

GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI-DETECTED BLAZARS (2010, methodology): “In agreement with the results of Section 3 and the spectral results reported in Abdo et al. (2010b), the HSP BL Lac objects are well separated, being at the lowest redshift and least variable sources (with the exception of ON 325 as mentioned in the previous section).”
THE EXTRAGALACTIC BACKGROUND LIGHT, THE HUBBLE CONSTANT, AND ANOMALIES: CONCLUSIONS FROM 20 YEARS OF TeV GAMMA-RAY OBSERVATIONS (2015, background): “Photon indices have proven quite stable in the HE band except during flaring events, despite the rather high flux variability at all timescales that is characteristic of blazars (see, e.g., Abdo et al. 2010).”
FERMIGAMMA-RAY SPACE TELESCOPE OBSERVATIONS OF THE GAMMA-RAY OUTBURST FROM 3C454.3 IN NOVEMBER 2010 (2011, background): “Note that in the ﬁrst LAT AGN catalog (Abdo et al. 2010a), less than 2% of FSRQs are found with 11-month averaged Γ < 2.1.”
THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2015, methodology): “All the 1FGL sources, detected in 11 months of exposure, were subsequently studied with 15 months of data (Abdo et al. 2010e).”
INSIGHTS INTO THE HIGH-ENERGY γ-RAY EMISSION OF MARKARIAN 501 FROM EXTENSIVE MULTIFREQUENCY OBSERVATIONS IN THE FERMI ERA (2011, background): “This is the most complete quasi-simultaneous SED ever collected for Mrk 501, or for any other TeV-emitting BL Lac (see also Abdo et al. 2010d, in preparation).”
GeV BREAKS IN BLAZARS AS A RESULT OF GAMMA-RAY ABSORPTION WITHIN THE BROAD-LINE REGION (2010, methodology): “A surprising result is that the spectra of high-luminosity sources, flat-spectra radio quasars (FSRQs) and low-energy synchrotron peaked BL Lac objects, are much better described by a broken power law than by a simple powerlaw or any smoothly curved models (Abdo et al. 2009a, 2010).”
THE LUMINOSITY FUNCTION OF FERMI-DETECTED FLAT-SPECTRUM RADIO QUASARS (2011, methodology): “This is done in order to reproduce the inherent systematic uncertainty of ﬁtting the curved spectrum of a source with a power law (Abdo et al. 2010a).”
The intergalactic magnetic field constrained by Fermi/LAT observations of the TeV blazar 1ES 0229+200 (2010, background): “Following Abdo et al. (2010a), upper limits have been calculated looking at the flux satisfying2∆ log(L) = 4 when increasing the flux from the value minimizing the likelihoodL.”
The extragalactic background light and the gamma-ray opacity of the universe (2012, background): “…in the GeV regime (Abdo, A. A. et al., 2010), while the spectra of other blazars (Mrk 421, Abdo et al., 2011b), (Mrk 501, Abdo et al., 2011a) extend without any cutoff to 300 GeV (Abdo et al., 2010b), or multi-TeV energies (Krennrich et al., 2002), depending on the flaring state of the source.”
THE FIRST CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2010, methodology): “This source is associated with M82, also known as NGC 3034 and 3C 231, a starburst galaxy previously detected by the LAT (Abdo et al. 2010d).”
THE FERMI-LAT HIGH-LATITUDE SURVEY: SOURCE COUNT DISTRIBUTIONS AND THE ORIGIN OF THE EXTRAGALACTIC DIFFUSE BACKGROUND (2010, methodology): “This procedure is correctly implemented in Abdo et al. (2010b).”