Study of the X-ray emission mechanism of radio-loud narrow-line Seyfert 1 galaxy

TL;DR

This study investigates the X-ray emission mechanisms of the radio-loud narrow-line Seyfert 1 galaxy 1H0323+342 by analyzing multi-epoch Suzaku observations, revealing multiple independent emission components and complex spectral features.

Contribution

It provides new insights into the X-ray spectral components and variability of RL-NLS1 galaxies, highlighting the presence of multiple emission processes.

Findings

Different variability in energy bands below 1 keV and above 7 keV.

X-ray spectrum requires complex models like broken power-law or reflection.

Spectral components vary independently.

Abstract

1H0323+342 is one of narrow-line radio-loud Seyfert 1 galaxies (RL-NLS1), which is a new class of gamma-ray emitting AGNs. Narrow-line Seyfert 1 galaxies (NLS1) have a small-mass black hole, but its mass accretion rate is almost as high as Eddington limit. Therefore, by observing NLS1s, we can know the evolution of supermassive black holes at the center of galaxies. Some of NLS1s are radio-loud and we call them RL-NLS1. From past observations, multi-wavelength spectrum of RL-NLS1s is similar to that of typical blazars; the synchrotron emission in the lower energy band up to the optical band, and inverse Compton scattering of low energy photons from disk, torus, and broad line region. X-ray band is a transittion region between the synchrotron and inverse Compton, and also there is a possible disk/corona emission. Therefore, we studied the energy-dependence of time variability of the X-ray emission of 1H0323+342, which have been observed by Suzaku in 2009 and 2013, in order to constrain the emission mechanism. We found that the lower energy below 1 keV and the higher energy above 7 keV show a different variability from the middle energy band, indicating at least two emission components in the X-ray band. X-ray spectrum is not a simple power-law, but requires an additional features; a broken power-law plus flat hard component, or a power-law plus a relativistic reflection component. Each spectral component seems to vary independently.