Spectral fittings of warm coronal radiation with high seed photon temperature: apparent low-temperature and flat soft excess in AGNs
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arXiv
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| Natura: | Preprint |
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2024
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| _version_ | 1866917674033872896 |
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| author | Tang, Ze-Yuan Feng, Jun-Jie Fan, Jun-Hui |
| author_facet | Tang, Ze-Yuan Feng, Jun-Jie Fan, Jun-Hui |
| contents | A warm corona has been widely proposed to explain the soft X-ray excess (SE) above the 2--10 keV power law extrapolation in AGNs. In actual spectral fittings, the warm coronal seed photon temperature ($T_{\rm s}$) is usually assumed to be far away from the soft X-ray, but $kT_{\rm s}$ can reach close to 0.1 keV in standard accretion disc 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 \textsc{thcomp} or a thermal component. Our findings reveal that high $T_{\rm s}$ can influence the fitting results. A moderately high $kT_{\rm s}$ (around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high $kT_{\rm s}$ (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), $kT_{\rm s}$ should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when $kT_{\rm s}>0.01$ keV. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_15156 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Spectral fittings of warm coronal radiation with high seed photon temperature: apparent low-temperature and flat soft excess in AGNs Tang, Ze-Yuan Feng, Jun-Jie Fan, Jun-Hui High Energy Astrophysical Phenomena A warm corona has been widely proposed to explain the soft X-ray excess (SE) above the 2--10 keV power law extrapolation in AGNs. In actual spectral fittings, the warm coronal seed photon temperature ($T_{\rm s}$) is usually assumed to be far away from the soft X-ray, but $kT_{\rm s}$ can reach close to 0.1 keV in standard accretion disc 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 \textsc{thcomp} or a thermal component. Our findings reveal that high $T_{\rm s}$ can influence the fitting results. A moderately high $kT_{\rm s}$ (around 0.03 keV) can result in an apparent low-temperature and flat SE, while an extremely high $kT_{\rm s}$ (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), $kT_{\rm s}$ should be treated as a free parameter with an upper limit, and an accurate coronal geometry is necessary when $kT_{\rm s}>0.01$ keV. |
| title | Spectral fittings of warm coronal radiation with high seed photon temperature: apparent low-temperature and flat soft excess in AGNs |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2405.15156 |