Ursini, F;
Marinucci, A;
Matt, G;
Bianchi, S;
Marin, F;
Marshall, HL;
Middei, R;
... Zane, S; + view all
(2022)
Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer.
Monthly Notices of the Royal Astronomical Society
10.1093/mnras/stac3189.
(In press).
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Abstract
We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source to be significantly polarized in the 2–6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysis indicates that the polarization degree is 28 ± 7 per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of 18○ ± 5○, roughly perpendicular to the radio jet. The polarization of the ionized reflection is unconstrained. A comparison with Monte Carlo simulations of the polarization expected from the torus shows that the neutral reflector is consistent with being an equatorial torus with a half-opening angle of 45○–55○. This is the first X-ray polarization detection in a Seyfert galaxy, demonstrating the power of X-ray polarimetry in probing the geometry of the circumnuclear regions of AGNs, and confirming the basic predictions of standard Unification Models.
| Type: | Article |
|---|---|
| Title: | Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stac3189 |
| Publisher version: | https://doi.org/10.1093/mnras/stac3189 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: active, galaxies: individual: Circinus, galaxies: Seyfert, polarization, scattering, X-rays: galaxies |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10159158 |
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