{
  "id": "2407.17243",
  "version": "v1",
  "published": "2024-07-24T13:02:20.000Z",
  "updated": "2024-07-24T13:02:20.000Z",
  "title": "A second view on the X-ray polarization of NGC 4151 with IXPE",
  "authors": [
    "V. E. Gianolli",
    "S. Bianchi",
    "E. Kammoun",
    "A. Gnarini",
    "A. Marinucci",
    "F. Ursini",
    "M. Parra",
    "A. Tortosa",
    "A. De Rosa",
    "D. E. Kim",
    "F. Marin",
    "G. Matt",
    "R. Serafinelli",
    "P. Soffitta",
    "D. Tagliacozzo",
    "L. Di Gesu",
    "C. Done",
    "H. L. Marshall",
    "R. Middei",
    "R. Mikusincova",
    "P-O. Petrucci",
    "S. Ravi",
    "J. Svoboda",
    "F. Tombesi"
  ],
  "comment": "10 pages, 8 figures, 3 tables. Submitted to Astronomy & Astrophysics",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA"
  ],
  "abstract": "We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; {\\sim}750 ks), NuSTAR ({\\sim}60 ks), XMM-Newton ({\\sim}75 ks), and NICER ({\\sim}65 ks) pointings. NGC 4151 is the first Type 1 radio-quiet Seyfert galaxy with constrained polarization properties for the X-ray corona. Despite the lower flux state in which the source is re-observed and the resulting higher contribution of the constant reflection component in the IXPE energy band, our results are in agreement with the first detection. From the polarimetric analysis, a polarization degree {\\Pi} = 4.7 {\\pm} 1.3 per cent and angle {\\Psi} = 77{\\deg} {\\pm} 8{\\deg} east of north (68 per cent confidence level) are derived in the 2.0 - 8.0 keV energy range. Combining the two observations leads to polarization properties that are more constrained than those of the individual detections, showing {\\Pi} = 4.5 {\\pm} 0.9 per cent and {\\Psi} = 81{\\deg} {\\pm} 6{\\deg} (with detection significance {\\sim}4.6{\\sigma}). The observed polarization angle aligns very well with the radio emission in this source, supporting, together with the significant polarization degree, a slab or wedge geometry for the X-ray corona. However, a switch in the polarization angle at low energies (37{\\deg} {\\pm} 7{\\deg} in the 2 - 3.5 keV bin) suggests the presence of another component. When it is included in the spectro-polarimetric fit, a high polarization degree disfavors an interpretation in terms of a leakage through the absorbers, rather pointing to scattering from some kind of mirror.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-07-24T13:02:20.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray polarization",
      "second view",
      "polarization properties",
      "x-ray corona",
      "high polarization degree disfavors"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}