{
  "id": "2410.23104",
  "version": "v1",
  "published": "2024-10-30T15:15:13.000Z",
  "updated": "2024-10-30T15:15:13.000Z",
  "title": "A multi-faceted view of the X-ray spectral variability in Seyfert galaxy Ark 120",
  "authors": [
    "Lu-Xin Ren",
    "Jun-Xian Wang",
    "Jia-Lai Kang"
  ],
  "comment": "13 pages, 11 figures, submitted. Comments are very welcome!",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA"
  ],
  "abstract": "Utilizing a range of techniques including multi-band light curves, softness ratio analysis, structure functions, rms spectra, cross-correlation functions, and ratios of spectra from different intervals, we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120, through re-analyzing its six XMM-Newton observations taken between 2003 and 2014. We find a clear ''softer-when-brighter\" trend in the 2--10 keV power-law component over long timescales, with this trend being timescale dependent, as it is much weaker on shorter timescales, similar to that previously detected in NGC 4051. Notably, a rare ''harder-when-brighter\" trend is observed during one exposure, indicating dynamic changes in the spectral variability behavior of the power-law component. This exceptional exposure, with the spectral variability indeed marked by a power-law pivoting at an unusually low energy of ~ 2 keV, suggests intricate variations in the thermal Comptonization processes within the corona. Furthermore, when the data below 2 keV are included, we identify that the soft excess component adds significant complexity to the spectral variability, such as evidenced by a transition from ''harder-when-brighter'' to ''softer-when-brighter'' during another single exposure. Such extra complexity arises because the variability of the soft excess sometimes follows and sometimes does not follow the changes in the power-law component. Our findings underscore the necessity of applying multiple analytic techniques to fully capture the multifaceted spectral variability of AGNs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-10-30T15:15:13.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray spectral variability",
      "seyfert galaxy ark",
      "multi-faceted view",
      "power-law component",
      "excess component adds significant complexity"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 13,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}