The Astrophysical Journal (Jan 2024)
Study of γ-Ray Emission from a Compact Radio Galaxy with the Fermi Large Area Telescope
Abstract
The radio galaxy PKS 1007+142 is classified as a compact steep-spectrum source (CSS) and belongs to the class of young active galactic nuclei (AGNs). In this paper, we investigate the γ -ray emission from this CSS by conducting a comprehensive analysis of the 15 yr Fermi Large Area Telescope (Fermi-LAT) observation data. The Fermi-LAT latest Source Catalog, 4FGL-DR4, includes an unassociated γ -ray source, 4FGL J1010.0+1416, located at 0.°24 away from the radio position of PKS 1007+142. Using the 15 yr Fermi-LAT observation data, we reestimate the best-fit position of the γ -ray source and find that PKS 1007+142 is in close proximity to the γ -ray source and falls within its 68% error circle. Therefore, we conclude that PKS 1007+142 is the most plausible counterpart to the unassociated LAT source with detection test statistics ∼ 43.4 (∼6.6 σ ). PKS 1007+142 exhibits a steep power-law spectrum in the 0.1–300 GeV band, with a photon spectral index (Γ _γ ) of 2.86 ± 0.17. The average flux in the considered time interval is (2.14 ± 0.34) × 10 ^−12 erg cm ^−2 s ^−1 . Comparing PKS 1007+142 with other γ -ray emitting AGNs in both the L _γ –Γ _γ and L _γ – L _1.4 GHz planes, it shows a softer γ -ray spectrum and lower luminosity compared to other γ -ray emitting CSSs. Furthermore, the possible origins of γ -ray in PKS 1007+142 are also discussed.
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