PoS - Proceedings of Science
Volume 444 - 38th International Cosmic Ray Conference (ICRC2023) - Gamma-ray Astronomy (GA)
Investigating the Nature of the Hard X-ray/Soft Gamma-ray Emission from Centaurus A
J.ย Rodi*, E.ย Jourdain, M.ย Molina and J.P.ย Roques
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Pre-published on: August 09, 2023
Published on: โ€”
The question of the origin of the hard X-ray/soft gamma-ray emission in Centaurus A (Cen A) persists despite decades of observations. Low energy results from X-ray instruments suggest a jet origin. In contrast, high energy X-ray/soft gamma-ray instruments find electron temperatures indicating a corona origin is possible. The spectral energy distribution (SED) peaks in this energy range so understanding the origin of this emission is critical to modelling it. We analyzed
INTEGRAL/IBIS-ISGRI and SPI data and observations over nearly 20 years. We did not find any spectral variability so we combined all observations for long-term average spectra. A NuSTAR observation was also added to study the 3.5 keV - 2.2 MeV spectrum. Spectral fits using a CompTT model found ๐‘˜๐‘‡๐‘’ ~ 520 keV, near pair-production runaway. The spectrum was also well described by a log-parabola to model synchrotron self-Compton emission (SSC) from the jet. Using a
log-parabola can explain the data up to ~ 3 GeV when including the 12-year catalog Fermi/LAT spectrum. Including a corona spectral component to model the hard X-rays/soft gamma-rays and a log-parabola for MeV to GeV emission can also well-describe the data, but the spectral parameters are poorly constrained. Thus, the hard X-ray/soft gamma-ray emission is likely due to SSC jet emission.
DOI: https://doi.org/10.22323/1.444.0650
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