The centre of the Milky Way Galaxy hosts a black hole with a solar mass of about 4 million (Sagittarius A* (Sgr A)) that is very quiescent at present with a luminosity many orders of magnitude below those of active galactic nuclei1. Reflection of X-rays from Sgr A* by dense gas in the Galactic Centre region offers a means to study its past flaring activity on timescales of hundreds and thousands of years2. The shape of the X-ray continuum and the strong fluorescent iron line observed from giant molecular clouds in the vicinity of Sgr A* are consistent with the reflection scenario3-5. If this interpretation is correct, the reflected continuum emission should be polarized6. 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 degrees +/- 11 degrees. The polarization angle is consistent with Sgr A* being the primary source of the emission, and the polarization degree implies that some 200 years ago, the X-ray luminosity of Sgr A* was briefly comparable to that of a Seyfert galaxy.

Marin, F., Churazov, E., Khabibullin, I., Ferrazzoli, R., Di Gesu, L., Barnouin, T., et al. (2023). X-ray polarization evidence for a 200-year-old flare of Sgr A*. NATURE, 619(7968), 41-45 [10.1038/s41586-023-06064-x].

X-ray polarization evidence for a 200-year-old flare of Sgr A*

Di Marco, Alessandro;Fabiani, Sergio;La Monaca, Fabio;Rankin, John;Tombesi, Francesco;
2023-07-01

Abstract

The centre of the Milky Way Galaxy hosts a black hole with a solar mass of about 4 million (Sagittarius A* (Sgr A)) that is very quiescent at present with a luminosity many orders of magnitude below those of active galactic nuclei1. Reflection of X-rays from Sgr A* by dense gas in the Galactic Centre region offers a means to study its past flaring activity on timescales of hundreds and thousands of years2. The shape of the X-ray continuum and the strong fluorescent iron line observed from giant molecular clouds in the vicinity of Sgr A* are consistent with the reflection scenario3-5. If this interpretation is correct, the reflected continuum emission should be polarized6. 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 degrees +/- 11 degrees. The polarization angle is consistent with Sgr A* being the primary source of the emission, and the polarization degree implies that some 200 years ago, the X-ray luminosity of Sgr A* was briefly comparable to that of a Seyfert galaxy.
lug-2023
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/05
English
Con Impact Factor ISI
Marin, F., Churazov, E., Khabibullin, I., Ferrazzoli, R., Di Gesu, L., Barnouin, T., et al. (2023). X-ray polarization evidence for a 200-year-old flare of Sgr A*. NATURE, 619(7968), 41-45 [10.1038/s41586-023-06064-x].
Marin, F; Churazov, E; Khabibullin, I; Ferrazzoli, R; Di Gesu, L; Barnouin, T; Di Marco, A; Middei, R; Vikhlinin, A; Costa, E; Soffitta, P; Muleri, F;...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/339554
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