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arXiv · 2501.11118

X-ray timing and spectral characteristics of compact symmetric objects

Subhashree Swain·C. S. Stalin·Vaidehi S. Paliya·D. J. Saikia
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Abstract

Compact Symmetric Objects (CSOs) are a distinct category of jetted active galactic nuclei whose high-energy emission is not well understood. We examined the X-ray characteristics of 17 bona fide CSOs using observations from Chandra, XMM-Newton and NuSTAR. Among the sources with XMM-Newton observations, we found two sources, J0713+4349 and J1326+3154 to show clear evidence of variations in the soft (0.3$-$2 keV), the hard (2$-$10 keV) and the total energy (0.3$-$10 keV) bands with the normalised excess variance (F$_{var}$) as large as 1.17$\pm$0.27. Also, the F$_{var}$ is found to be larger in the hard band relative to the soft band for J1326+3154. From the analysis of the hardness ratio (HR) with count rate, we found both sources to show a harder when brighter (HWB) trend. Similarly, in the Chandra observations, we found one source, J0131+5545, to show flux variations in the total energy band (0.5$-$7 keV). We discuss possible reasons for about 82 per cent of the CSOs being non-variable. From spectral analysis, carried out in a homogeneous manner, we found the existence of obscured as well as unobscured CSOs. Three CSOs, J0111+3906, J1407+2827 and J2022+6136, were found to have the intrinsic neutral hydrogen column density N$_{\rm H,z} > 10^{23}$ cm$^{-2}$, consistent with earlier analyses. For the majority of the CSOs, the observed hard X-ray emission is expected to be dominated by their mildly relativistic jet emission. For the sources, J0713+4349, J1347+1217, J1407+2827, J1511+0518 and J2022+6136, the confirmed detection of Fe K$\alpha$ emission line suggests a significant contribution from the disk/corona. Our results point to diverse X-ray characteristics of CSOs.

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Subhashree Swain, C. S. Stalin, Vaidehi S. Paliya, D. J. Saikia. 2025-01-19. X-ray timing and spectral characteristics of compact symmetric objects. https://arxiv.org/abs/2501.11118

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