X-ray polarization evidence for a 200-year-old flare of Sgr A<SUP>*</SUP>

DOI: 
10.1038/s41586-023-06064-x
Publication date: 
31/07/2023
Main author: 
Marin, Frédéric
IAA authors: 
Agudo, Iván
Authors: 
Marin, Frédéric;Churazov, Eugene;Khabibullin, Ildar;Ferrazzoli, Riccardo;Di Gesu, Laura;Barnouin, Thibault;Di Marco, Alessandro;Middei, Riccardo;Vikhlinin, Alexey;Costa, Enrico;Soffitta, Paolo;Muleri, Fabio;Sunyaev, Rashid;Forman, William;Kraft, Ralph;Bianchi, Stefano;Donnarumma, Immacolata;Petrucci, Pierre-Olivier;Enoto, Teruaki;Agudo, Iván;Antonelli, Lucio A.;Bachetti, Matteo;Baldini, Luca;Baumgartner, Wayne H.;Bellazzini, Ronaldo;Bongiorno, Stephen D.;Bonino, Raffaella;Brez, Alessandro;Bucciantini, Niccolò;Capitanio, Fiamma;Castellano, Simone;Cavazzuti, Elisabetta;Chen, Chien-Ting;Ciprini, Stefano;De Rosa, Alessandra;Del Monte, Ettore;Di Lalla, Niccolò;Doroshenko, Victor;Dovčiak, Michal;Ehlert, Steven R.;Evangelista, Yuri;Fabiani, Sergio;Garcia, Javier A.;Gunji, Shuichi;Hayashida, Kiyoshi;Heyl, Jeremy;Ingram, Adam;Iwakiri, Wataru;Jorstad, Svetlana G.;Kaaret, Philip;Karas, Vladimir;Kitaguchi, Takao;Kolodziejczak, Jeffery J.;Krawczynski, Henric;La Monaca, Fabio;Latronico, Luca;Liodakis, Ioannis;Maldera, Simone;Manfreda, Alberto;Marinucci, Andrea;Marscher, Alan P.;Marshall, Herman L.;Massaro, Francesco;Matt, Giorgio;Mitsuishi, Ikuyuki;Mizuno, Tsunefumi;Negro, Michela;Ng, C. -Y.;O'Dell, Stephen L.;Omodei, Nicola;Oppedisano, Chiara;Papitto, Alessandro;Pavlov, George G.;Peirson, Abel L.;Perri, Matteo;Pesce-Rollins, Melissa;Pilia, Maura;Possenti, Andrea;Poutanen, Juri;Puccetti, Simonetta;Ramsey, Brian D.;Rankin, John;Ratheesh, Ajay;Roberts, Oliver J.;Romani, Roger W.;Sgrò, Carmelo;Slane, Patrick;Spandre, Gloria;Swartz, Doug;Tamagawa, Toru;Tavecchio, Fabrizio;Taverna, Roberto;Tawara, Yuzuru;Tennant, Allyn F.;Thomas, Nicholas E.;Tombesi, Francesco;Trois, Alessio;Tsygankov, Sergey S.;Turolla, Roberto;Vink, Jacco;Weisskopf, Martin C.;Wu, Kinwah;Xie, Fei;Zane, Silvia
Journal: 
Nature
Publication type: 
Article
Volume: 
619
Pages: 
41
Abstract: 
The centre of the Milky Way Galaxy hosts a black hole with a solar mass of about 4 million (Sagittarius A<SUP>*</SUP> (Sgr A)) that is very quiescent at present with a luminosity many orders of magnitude below those of active galactic nuclei<SUP>1</SUP>. Reflection of X-rays from Sgr A<SUP>*</SUP> by dense gas in the Galactic Centre region offers a means to study its past flaring activity on timescales of hundreds and thousands of years<SUP>2</SUP>. The shape of the X-ray continuum and the strong fluorescent iron line observed from giant molecular clouds in the vicinity of Sgr A<SUP>*</SUP> are consistent with the reflection scenario<SUP>3-5</SUP>. If this interpretation is correct, the reflected continuum emission should be polarized<SUP>6</SUP>. Here we report observations of polarized X-ray emission in the direction of the molecular clouds in the Galactic Centre using the Imaging X-ray Polarimetry Explorer. We measure a polarization degree of 31% ± 11%, and a polarization angle of −48° ± 11°. The polarization angle is consistent with Sgr A<SUP>*</SUP> being the primary source of the emission, and the polarization degree implies that some 200 years ago, the X-ray luminosity of Sgr A<SUP>*</SUP> was briefly comparable to that of a Seyfert galaxy.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2023Natur.619...41M/abstract
ADS Bibcode: 
2023Natur.619...41M