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The corona is an integral component of active galactic nuclei (AGNs) which produces the bulk of the X-ray emission above 1-2 keV. However, many of its physical properties and the mechanisms powering this emission remain a mystery. In particular, the temperature of the coronal plasma has been difficult to constrain for large samples of AGNs, as constraints require high-quality broadband X-ray spectral coverage extending above 10 keV in order to measure the high-energy cutoff, which provides constraints on the combination of coronal optical depth and temperature. We present constraints on the coronal temperature for a large sample of Seyfert 1 AGNs selected from the Swift/BAT survey using high-quality hard X-ray data from the NuSTAR observatory combined with simultaneous soft X-ray data from Swift/XRT or XMM-Newton. When applying a physically motivated, nonrelativistic disk-reflection model to the X-ray spectra, we find a mean coronal temperature kT e = 84 ± 9 keV. We find no significant correlation between the coronal cutoff energy and accretion parameters such as the Eddington ratio and black hole mass. We also do not find a statistically significant correlation between the X-ray photon index, Γ, and Eddington ratio. This calls into question the use of such relations to infer properties of supermassive black hole systems.
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This content will become publicly available on March 1, 2026
Exploring the disc-jet scenario in 3C 273 using simultaneous XMM-Newton and NuSTAR observations
Context.The well-studied active galactic nucleus (AGN) 3C 273 displays characteristics of both jetted-AGNs and Seyfert galaxies, which makes it an excellent source to study the disc-jet connection in AGNs. Aims.We aim to investigate the disc-jet scenario in 3C 273 using broad-band (0.3–78 keV) X-ray spectra fromXMM-NewtonandNuSTAR. Methods.We used simultaneousXMM-NewtonandNuSTARobservations of 3C 273 carried out between 2012 and 2024. The 0.3–78 keV X-ray spectra were first fitted with a simple power law (PL) and then with the accretion-ejection-basedJeTCAFmodel. TheJeTCAFmodel accounts for emission from the jet, which extends up to the sonic surface. In this framework, a reflection hump above 10 keV can also arise due to the bulk motion Comptonization of coronal photons by the jet. Results.We find that the simple PL did not provide a good fit, leaving significant residuals at energies below 1.5 keV. All the spectra were fitted well by theJeTCAFmodel. The weighted-averaged black hole mass of (7.77 ± 0.30) × 108 M⊙obtained from theJeTCAFmodel is comparable with the previous estimates based on reverberation mapping observations and accretion disc models. Conclusions.The 0.3–78 keV X-ray emission of 3C 273 can be fit by the accretion-ejection-based model in which the corona and the jet on top of it make significant contributions to the X-ray flux. The Doppler boosting factor estimated from the jet flux ranges from 1.6 to 2.2, consistent with the lower limit from the literature.
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- PAR ID:
- 10621744
- Publisher / Repository:
- EDP Sciences
- Date Published:
- Journal Name:
- Astronomy & Astrophysics
- Volume:
- 695
- ISSN:
- 0004-6361
- Page Range / eLocation ID:
- A120
- Subject(s) / Keyword(s):
- accretion / accretion disks / galaxies: active / galaxies: jets / X-rays: individuals: 3C 273
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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