![]() ![]() SRG/eROSITA view of X-ray reflection in the Central Molecular Zone: a snapshot in September-October 2019. Polarization of X-ray emission from the Sgr B2 cloud. ASCA view of our Galactic Center: remains of past activities in X-rays? Publ. Two sources of diffuse X-ray emission from the Galactic Centre. The center of the Galaxy in the recent past: a view from GRANAT. ![]() The K-alpha lines in the background X-ray spectrum and the interstellar gas in galaxies. The Galactic Center massive black hole and nuclear star cluster. 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. We measure a polarization degree of 31% ± 11%, and a polarization angle of −48° ± 11°. 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. If this interpretation is correct, the reflected continuum emission should be polarized 6. 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 scenario 3, 4, 5. 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 years 2. 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 nuclei 1. Nature volume 619, pages 41–45 ( 2023) Cite this article X-ray polarization evidence for a 200-year-old flare of Sgr A *
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