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Spectral Fittings of Warm Coronal Radiation with High Seed Photon Temperature: Apparent Low-temperature and Flat Soft Excess in AGNs
A warm corona has been widely proposed to explain the soft excess (SE) in X-ray above the 2–10 keV power law extrapolation in Active Galactic Nuclei (AGNs). In actual spectral fittings, the warm coronal seed photon temperature ( T s ) is usually assumed to be far away from the soft X-ray, but kT s c...
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Published in: | Research in astronomy and astrophysics 2024-07, Vol.24 (7), p.75010 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites |
Online Access: | Get full text |
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Summary: | A warm corona has been widely proposed to explain the soft excess (SE) in X-ray above the 2–10 keV power law extrapolation in Active Galactic Nuclei (AGNs). In actual spectral fittings, the warm coronal seed photon temperature (
T
s
) is usually assumed to be far away from the soft X-ray, but
kT
s
can reach close to 0.1 keV in the standard accretion disk model. In this study, we used Monte Carlo simulations to obtain radiation spectra from a slab-like warm corona and fitted the spectra using the spherical-geometry-based routine
thcomp
or a thermal component. Our findings reveal that high
T
s
can influence the fitting results. A moderately high
kT
s
(around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high
kT
s
(around 0.07 keV) can even produce an unobserved blackbody-like SE. Our conclusions indicate that, for spectral fittings of the warm coronal radiation (SE in AGNs),
kT
s
should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when
kT
s
> 0.01 keV. |
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ISSN: | 1674-4527 2397-6209 |
DOI: | 10.1088/1674-4527/ad4fc5 |