2025A&A...695A.120P

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 from XMM-Newton and NuSTAR.
Methods. We used simultaneous XMM-Newton and NuSTAR observations 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-based JeTCAF model. The JeTCAF model 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 the JeTCAF model. The weighted-averaged black hole mass of (7.77 ± 0.30) × 10⁸ M_⊙ obtained from the JeTCAF model 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.