The X-ray emission in young radio active galactic nuclei

Abstract

In this work, we investigated the X-ray emission for a sample of young radio AGNs by combining their data from Chandra/XMM-Newton and at other wavebands. We find strong correlations between the X-ray luminosity LX in 2−10 keV and the radio luminosities LR at 5 GHz for VLBI radio-core, VLA radio-core and FIRST component, indicating that both pc- and kpc-scale radio emission strongly correlate with X-ray emission in these sources. We find approximately linear dependence of radio on X-ray luminosity in the sources with radiative efficient accretion flows (i.e., the Eddington ratio Redd ≳ 10−3) with b ∼ 1 (LR ∝ $L_{\rm X} ^{b}$) and ξRX ∼ 1 in fundamental plane using VLBI data, where the dependence is consistent with the re-analysed result on the previous study in Fan & Bai(2016) at Redd ≳ 10−3, however is significantly deviated from the theoretical prediction of accretion flow as the origin of X-ray emission. In contrast to radio-quiet quasars, there is no significant correlation between Γ and Eddington ratio. Our results seem to indicate that the X-ray emission of high-accreting young radio AGNs may be from jet. We constructed the SEDs for 18 sources (most are in radiative efficient accretion) including 9 galaxies and 9 quasars with high-quality X-ray data, and find that the X-ray emission of most quasars is more luminous than that of normal radio-quiet quasars. This is clearly seen from the quasar composite SED, of which the X-ray emission is apparently higher than that of radio-quiet quasars, likely supporting the jet-related X-ray emission in young radio AGNs. The scenario that the X-ray emission is from self-synchrotron Compton (SSC) is discussed.

The Unified Models for Black Hole Accretions

“…There are several works exploring the fundamental plane relation on CSOs [25][26][27]. Most of the results suggest CSOs do deviate from the classical trends.…”

Investigations on the optical properties and X‐ray emission in compact radio active galactic nuclei

“…These results strongly indicate that the compact radio AGN will eventually evolve into large-scale radio sources in general. But see the discussion on the compact radio sources with low luminosity and low accretion rate in Liao & Gu (2020), which suggest that some are short-lived sources and cannot grow into large-scale ones.…”

“…The black solid (dashed lines) are the expected evolutionary tracks based on parametric modeling for the high-luminosity (low-luminosity radio sources) in An & Baan (2012) XMM-Newton X-ray archives, and including additional two CSS radio sources of 3C 305 and 4C 13.66. After excluding six objects that are too faint and either lensed or significant in X-ray spectral variability (see more details in Liao et al 2020), the X-ray data are thus available in 85 sources.…”

“…Our X‐ray sample consists of 91 sources, which was built by cross‐matching our parent sample with Chandra and XMM‐Newton X‐ray archives, and including additional two CSS radio sources of 3C 305 and 4C 13.66. After excluding six objects that are too faint and either lensed or significant in X‐ray spectral variability (see more details in Liao et al 2020), the X‐ray data are thus available in 85 sources.…”

“…We found strong correlations between the X‐ray luminosity at 2–10 keV and the radio luminosity at 5 GHz of VLA, FIRST, and VLBI, implying that both pc‐ and kpc‐scale radio emission have tight relation with X‐ray emission. The ordinary least squares bisetor (Isobe et al 1990) fits to the correlations between and give that approximately linear relations between log and log with the slope b equal about 1 (see more details in Liao et al 2020).…”