X-Ray Emission Properties of a Compact Symmetric Object Sample

Abstract

We present a comprehensive analysis of the X-ray observations obtained from XMM-Newton and Chandra for a sample of bona-fide Compact Symmetric Objects (CSOs) to investigate their X-ray emission properties. Ultimately, we obtain 32 effective X-ray observational spectra from 17 CSOs. Most spectra can be well described by an absorbed single power-law model, with the exception of six spectra requiring an additional component in the soft X-ray band and two spectra exhibiting an iron emission line component. The data analysis results unveil the diverse characteristics of X-ray emission from CSOs. The sample covers X-ray luminosity ranging within 10⁴⁰‑10⁴⁵ erg s^‑1, intrinsic absorbing column density ( ) ranging within 10²⁰‑10²³ cm^‑2, and photon spectral index (Γ_X) ranging within 0.75–3.0. None of the CSOs in our sample have > 10²³ cm^‑2, indicating that the X-ray emission in these CSOs is not highly obscured. The distribution of Γ_X for these CSOs closely resembles that observed in a sample of radio-loud quasars and low-excitation radio galaxies (RGs). In the radio–X-ray luminosity panel, these CSOs exhibit a distribution more akin to FR I RGs than FR II RGs, characterized by higher luminosities. The positive correlation between Γ_X and the Eddington ratio, which has been noted in radio-quiet active galactic nuclei, is not observed in these CSOs. These findings suggest that although the contribution of the disk-corona system cannot be completely ruled out, jet/lobe radiation likely plays a dominant role in the X-ray emission of these CSOs.