X-ray Emission Properties of a Compact Symmetric Object Sample

Abstract

We present a comprehensive analysis of the X-ray observations obtained from \xmm\, 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 6 spectra requiring an additional component in the soft X-ray band and 2 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 $10^{40}-10^{45}$ erg s${}^{-1}$, intrinsic absorbing column density ($N_{\mathrm{H}}^{\mathrm{int}}$) ranging within $10^{20}-10^{23}$ cm${}^{-2}$, and photon spectral index ($\hat{I}{“}_{\mathrm{X}}$) ranging within 0.75--3.0. None of the CSOs in our sample have $N_{\mathrm{H}}^{\mathrm{int}}$ > $10^{23}\mathrm{c}{\mathrm{m}}^{-2}$, indicating that the X-ray emission in these CSOs is not highly obscured. The distribution of $\hat{I}{“}_{\mathrm{X}}$ 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 $\hat{I}{“}_{\mathrm{X}}$ 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.

25 Pages, 8 Figures, 7 Tables, accepted for publication in ApJ