2013/06/07 by V. A. Dogiel, D. O. Chernyshov, V. Tatischeff +3
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Atomic physics #Cosmic ray #Electron #Galactic Center #Galaxy #Interstellar medium #Ion #Ionization #Line (geometry) #Luminosity #Nuclear physics #Optics #Photon #Physics #Supermassive black hole #astro-ph.HE
paper · pdf · doi:10.1088/2041-8205/771/2/l43
5 pages, 4 figues, accepted for publication in the Astrophysical Journal Letters
arxiv created 2013/06/07 · openalex publication_date 2013/06/27 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the origin of the diffuse 6.4 keV line emission recently detected by Suzaku and the source of H 2 ionization in the diffuse molecular gas of the Galactic center (GC) region. We show that Fe atoms and H 2 molecules in the diffuse interstellar medium of the GC are not ionized by the same particles. The Fe atoms are most likely ionized by X-ray photons emitted by Sgr A* during a previous period of flaring activity of the supermassive black hole. The measured longitudinal intensity distribution of the diffuse 6.4 keV line emission is best explained if the past activity of Sgr A* lasted at least several hundred years and released a mean 2–100 keV luminosity ≳ 10 38 erg s −1 . The H 2 molecules of the diffuse gas cannot be ionized by photons from Sgr A*, because soft photons are strongly absorbed in the interstellar gas around the central black hole. The molecular hydrogen in the GC region is most likely ionized by low-energy cosmic rays, probably protons rather than electrons, whose contribution into the diffuse 6.4 keV line emission is negligible.