| Title: |
Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer |
| Authors: |
Ehlert, Steven R.; FERRAZZOLI, Riccardo; Marinucci, Andrea; Marshall, Herman L.; MIDDEI, Riccardo; PACCIANI, LUIGI; PERRI, Matteo; Petrucci, Pierre-Olivier; Puccetti, Simonetta; Barnouin, Thibault; Bianchi, Stefano; Liodakis, Ioannis; Madejski, Grzegorz; Marin, Frédéric; Marscher, Alan P.; Matt, Giorgio; Poutanen, Juri; Wu, Kinwah; Agudo, Iván; ANTONELLI, Lucio Angelo; BACHETTI, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; BUCCIANTINI, Niccolo'; CAPITANIO, FIAMMA; Castellano, Simone; Cavazzuti, Elisabetta; Ciprini, Stefano; COSTA, ENRICO; DE ROSA, Alessandra; DEL MONTE, Ettore; Di Gesu, Laura; Di Lalla, Niccoló; DI MARCO, Alessandro; Donnarumma, Immacolata; Doroshenko, Victor; Dovčiak, Michal; Enoto, Teruaki; EVANGELISTA, YURI; FABIANI, Sergio; Garcia, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Jorstad, Svetlana G.; Karas, Vladimir; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Krawczynski, Henric; LA MONACA, Fabio; Latronico, Luca; Maldera, Simone; Manfreda, Alberto; MASSARO, Francesco; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; MULERI, FABIO; Negro, Michela; Ng, C. -Y.; O'Dell, Stephen L.; Omodei, Nicola; Oppedisano, Chiara; PAPITTO, ALESSANDRO; Pavlov, George G.; Peirson, Abel L.; Pesce-Rollins, Melissa; PILIA, Maura; POSSENTI, ANDREA; Ramsey, Brian D.; RANKIN, John; RATHEESH, AJAY; Romani, Roger W.; Sgrò, Carmelo; Slane, Patrick; SOFFITTA, PAOLO; Spandre, Gloria; Tamagawa, Toru; TAVECCHIO, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; TOMBESI, Francesco; TROIS, ALESSIO; Tsygankov, Sergey; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; XIE, FEI; Zane, Silvia; IXPE Collaboration; RODI, James Craig; Jourdain, Elisabeth; Roques, Jean-Pierre |
| Publication Year: |
2022 |
| Description: |
We present measurements of the polarization of X-rays in the 2-8 keV band from the nucleus of the radio galaxy Centaurus A (Cen A), using a 100 ks observation from the Imaging X-ray Polarimetry Explorer (IXPE). Nearly simultaneous observations of Cen A were also taken with the Swift, NuSTAR, and INTEGRAL observatories. No statistically significant degree of polarization is detected with IXPE. These observations have a minimum detectable polarization at 99% confidence (MDP 99 ) of 6.5% using a weighted, spectral model-independent calculation in the 2-8 keV band. The polarization angle ψ is consequently unconstrained. Spectral fitting across three orders of magnitude in X-ray energy (0.3-400 keV) demonstrates that the SED of Cen A is well described by a simple power law with moderate intrinsic absorption (N H ~ 10 23 cm -2 ) and a Fe Kα emission line, although a second unabsorbed power law is required to account for the observed spectrum at energies below 2 keV. This spectrum suggests that the reprocessing material responsible for this emission line is optically thin and distant from the central black hole. Our upper limits on the X-ray polarization are consistent with the predictions of Compton scattering, although the specific seed photon population responsible for the production of the X-rays cannot be identified. The low polarization degree, variability in the core emission, and the relative lack of variability in the Fe Kα emission line support a picture where electrons are accelerated in a region of highly disordered magnetic fields surrounding the innermost jet. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
THE ASTROPHYSICAL JOURNAL; http://hdl.handle.net/20.500.12386/36306; https://api.elsevier.com/content/abstract/scopus_id/85138196662 |
| DOI: |
10.3847/1538-4357/ac8056 |
| Availability: |
https://hdl.handle.net/20.500.12386/36306; https://doi.org/10.3847/1538-4357/ac8056; https://api.elsevier.com/content/abstract/scopus_id/85138196662; https://iopscience.iop.org/article/10.3847/1538-4357/ac8056 |
| Rights: |
open |
| Accession Number: |
edsbas.4656ADC0 |
| Database: |
BASE |