IGR J18249−3243: a new GeV-emitting FR II and the emerging population of high-energy radio galaxies
Date Issued
2022
Author(s)
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Rephaeli, Y
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Wieringa, M H
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Abstract
The advent of new all-sky radio surveys such as the VLA Sky Survey (VLASS)
and the Rapid ASKAP Continuum Survey (RACS), performed with the latest
generation radio telescopes, is opening new possibilities on the classification
and study of extragalactic $\gamma$-ray sources, specially the underrepresented
ones like radio galaxies. In particular, the enhanced sensitivity (sub-mJy
level) and resolution (a few arcsec) provides a better morphological and
spectral classification. In this work, we present the reclassification of a
Fermi-LAT source as a new FRII radio galaxy from the INTEGRAL sample found to
emit at GeV energies. Through a broad-band spectral fitting from radio to
$\gamma$-ray, we find that the commonly invoked jet contribution is not
sufficient to account for the observed $\gamma$-ray flux. Our modeling suggests
that the observed emission could mainly originate in the lobes (rather than in
the radio core) by inverse Compton scattering of radio-emitting electrons off
the ambient photon fields. In addition, we cross-correlated the latest
generation radio surveys with a list of Fermi-LAT objects from the literature
considered to be candidate misaligned AGN, finding four new radio galaxies with
a double-lobed morphology. Additional four objects could be classified as such
thanks to previous studies in the literature, for a total of nine new radio
galaxies with GeV emission presented in this work. We foresee that further
objects of this class might be found in the near future with the advent of the
Square Kilometer Array (SKA), populating the GeV sky.
Volume
513
Issue
1
Start page
886--899
Issn Identifier
0035-8711
Rights
open.access
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