Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer

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Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer. / IXPE.

In: Astrophysical Journal, Vol. 935, No. 2, 116, 01.08.2022.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{723bde7abdf040519209992793dc069a,

title = "Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer",

abstract = "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 (MDP99) 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 (NH ∼1023 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.",

author = "IXPE and Ehlert, {Steven R.} and Riccardo Ferrazzoli and Andrea Marinucci and Marshall, {Herman L.} and Riccardo Middei and Luigi Pacciani and Matteo Perri and Petrucci, {Pierre Olivier} and Simonetta Puccetti and Thibault Barnouin and Stefano Bianchi and Ioannis Liodakis and Grzegorz Madejski and Fr{\'e}d{\'e}ric Marin and Marscher, {Alan P.} and Giorgio Matt and Juri Poutanen and Kinwah Wu and Iv{\'a}n Agudo and Antonelli, {Lucio A.} and Matteo Bachetti and Luca Baldini and Baumgartner, {Wayne H.} and Ronaldo Bellazzini and Bongiorno, {Stephen D.} and Raffaella Bonino and Alessandro Brez and Niccol{\'o} Bucciantini and Fiamma Capitanio and Simone Castellano and Elisabetta Cavazzuti and Stefano Ciprini and Enrico Costa and {De Rosa}, Alessandra and {Del Monte}, Ettore and {Di Gesu}, Laura and {Di Lalla}, Niccol{\'o} and {Di Marco}, Alessandro and Immacolata Donnarumma and Victor Doroshenko and Michal Dov{\v c}iak and Teruaki Enoto and Yuri Evangelista and Sergio Fabiani and Garcia, {Javier A.} and Shuichi Gunji and Kiyoshi Hayashida and Jeremy Heyl and Wataru Iwakiri and Jorstad, {Svetlana G.}",

note = "Publisher Copyright: {\textcopyright} 2022. The Author(s).",

year = "2022",

month = aug,

day = "1",

doi = "10.3847/1538-4357/ac8056",

language = "English",

volume = "935",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

RIS

TY - JOUR

T1 - Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer

AU - IXPE

AU - Ehlert, Steven R.

AU - Ferrazzoli, Riccardo

AU - Marinucci, Andrea

AU - Marshall, Herman L.

AU - Middei, Riccardo

AU - Pacciani, Luigi

AU - Perri, Matteo

AU - Petrucci, Pierre Olivier

AU - Puccetti, Simonetta

AU - Barnouin, Thibault

AU - Bianchi, Stefano

AU - Liodakis, Ioannis

AU - Madejski, Grzegorz

AU - Marin, Frédéric

AU - Marscher, Alan P.

AU - Matt, Giorgio

AU - Poutanen, Juri

AU - Wu, Kinwah

AU - Agudo, Iván

AU - Antonelli, Lucio A.

AU - Bachetti, Matteo

AU - Baldini, Luca

AU - Baumgartner, Wayne H.

AU - Bellazzini, Ronaldo

AU - Bongiorno, Stephen D.

AU - Bonino, Raffaella

AU - Brez, Alessandro

AU - Bucciantini, Niccoló

AU - Capitanio, Fiamma

AU - Castellano, Simone

AU - Cavazzuti, Elisabetta

AU - Ciprini, Stefano

AU - Costa, Enrico

AU - De Rosa, Alessandra

AU - Del Monte, Ettore

AU - Di Gesu, Laura

AU - Di Lalla, Niccoló

AU - Di Marco, Alessandro

AU - Donnarumma, Immacolata

AU - Doroshenko, Victor

AU - Dovčiak, Michal

AU - Enoto, Teruaki

AU - Evangelista, Yuri

AU - Fabiani, Sergio

AU - Garcia, Javier A.

AU - Gunji, Shuichi

AU - Hayashida, Kiyoshi

AU - Heyl, Jeremy

AU - Iwakiri, Wataru

AU - Jorstad, Svetlana G.

PY - 2022/8/1

Y1 - 2022/8/1

N2 - 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 (MDP99) 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 (NH ∼1023 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.

AB - 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 (MDP99) 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 (NH ∼1023 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.

UR - http://www.scopus.com/inward/record.url?scp=85138196662&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/d2e4abf4-0cba-385c-af61-3bbd132c72af/

U2 - 10.3847/1538-4357/ac8056

DO - 10.3847/1538-4357/ac8056

M3 - Article

AN - SCOPUS:85138196662

VL - 935

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 116

ER -

ID: 99846739