A spectral hardening in the Fermi-LAT Data of 1ES 0502+675

Abstract

The $\gamma$-ray spectral feature of the blazar 1ES 0502+675 is investigated by using Fermi Large Area Telescope (Fermi-LAT) Pass 8 data (between 100 MeV and 300 GeV) covering from 2008 August to 2021 April. A significant ($\sim 4\sigma$) hardening at $\sim$ 1 GeV is found in the $\gamma$-ray spectrum during a moderately flaring state (MJD 55050-55350). The photon index below and above the break energy is ${\Gamma }_1=2.36\pm 0.31$ and ${\Gamma }_2=1.33\pm 0.11$, respectively. In the rest of the observations, the $\gamma$-ray spectrum can be described by a power-law form with the photon index of $\approx 1.6$. In the frame of a one-zone synchrotron self-Compton (SSC) model, the spectral hardening is interpreted as the transition between the synchrotron component and the SSC component. This could be the result of a slight increase of the break/maximum Lorentz factor of the electrons.

Accepted by MNRAS

References in corpus (8)

• Synchrotron Self-Compton Analysis of TeV X-ray Selected BL Lacertae Objects
• GeV breaks in blazars as a result of gamma-ray absorption within the broad-line region
• Gamma-Ray Studies of Blazars: Synchro-Compton Analysis of Flat Spectrum Radio Quasars
• Testing two-component models on very-high-energy gamma-ray emitting BL Lac objects
• High-energy emitting BL Lacs and high-energy neutrinos - Prospects for the direct association with IceCube and KM3NeT
• The Intrinsic Properties of Multiwavelength Energy Spectra for Fermi Teraelectronvolt Blazars
• On the origin of GeV spectral break for Fermi blazars: 3C 454.3
• Modeling the spectral-energy-distribution of 3C 454.3 in a "flat" broad-line-region scenario

Cited by in corpus (2)

• The Fermi-LAT view of the changing-look blazar OQ 334
• A Systematic Search for Spectral Hardening in Blazar Flares with the Fermi-Large Area Telescope