Fermi-LAT Observation of Non-Blazar AGNs

N. Sahakyan; V. Baghmanyan; D. Zargaryan

doi:10.1051/0004-6361/201732304

paper

Fermi-LAT Observation of Non-Blazar AGNs

arXiv:1801.09381 · doi:10.1051/0004-6361/201732304

Abstract

We report on a detailed investigation of the $γ$ -ray emission from 26 non-blazar AGNs based on the Fermi LAT data accumulated for 7 years. The photon index of non-blazar AGNs changes in the range of 1.84-2.86 and the flux varies from a few times $1 0^{- 9} p h o t o n c m^{- 2} s^{- 1}$ to $1 0^{- 7} p h o t o n c m^{- 2} s^{- 1}$ . Over long time periods, power-law provides an adequate description of the $γ$ -ray spectra of almost all sources. Significant curvature is observed in the $γ$ -ray spectra of NGC 1275, NGC 6251, SBS 0846+513 and PMN J0948+0022 and their spectra are better described by log-parabola or power-law with exponential cut-off models. The $γ$ -ray spectra of PKS 0625-25 and 3C 380 show a possible deviation from a simple power-law shape, indicating a spectral cutoff around the observed photon energy of $E_{c u t} = 131.2 \pm 88.04$ GeV and $E_{c u t} = 55.57 \pm 50.74$ GeV, respectively. Our analysis confirms the previous finding of an unusual spectral turnover in the $γ$ -ray spectrum of Cen A: the photon index changes from $2.75 \pm 0.02$ to $2.31 \pm 0.1$ at $2.35 \pm 0.08$ GeV. In the $Γ - L_{γ}$ plane, the luminosity of non-blazar AGNs is spread in the range of $1 0^{41} - 1 0^{47} er g s^{- 1}$ , where the lowest luminosity have FRI radio galaxies (but typically appear with a harder photon index) and the highest- SSRQs/NLSY1s (with softer photon indexes). We confirm the previously reported short-timescale flux variability of NGC 1275 and 3C 120. The $γ$ -ray emission from NLSY1s, 1H 0323+342, SBS 0846+513 and PMN J0948+0022, is variable, showing flares in short scales sometimes accompanied by a moderate hardening of their spectra (e.g., on MJD 56146.8 the $γ$ -ray photon index of SBS 0846+513 was $1.73 \pm 0.14$ ). 3C 111, Cen A core, 3C 207, 3C 275.1, 3C 380, 4C+39.23B, PKS 1502+036 and PKS 2004-447 show a long-timescale flux variability in the $γ$ -ray band.

Accepted for publication in Astronomy & Astrophysics. The abstract has been shortened to comply with the size limit set by arXiv

Fermi-LAT Observation of Non-Blazar AGNs

Abstract

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