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 10 40 −10 45 erg s −1 , intrinsic absorbing column density ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">int</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> ) ranging within 10 20 −10 23 cm −2 , and photon spectral index (Γ X ) ranging within 0.75–3.0. None of the CSOs in our sample have <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">int</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> &gt; 10 23 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.