K-shell Emission of Neutral Iron Line from Sgr B2 Excited by Subrelativistic Protons

Abstract

We investigated the emission of K$\alpha$ iron line from the massive molecular clouds in the Galactic center (GC). We assume that at present the total flux of this emission consists of time variable component generated by primary X-ray photons ejected by Sagittarius A${}^{\ast }$ (Sgr A${}^{\ast }$) in the past and a relatively weak quasi-stationary component excited by impact of protons which were generated by star accretion onto the central black hole. The level of background emission was estimated from a rise of the 6.4 keV line intensity in the direction of several molecular clouds, that we interpreted as a stage when the X-ray front ejected by Sgr A${}^{\ast }$ entered into these clouds. The 6.4 keV emission before this intensity jump we interpreted as emission generated by subrelativistic cosmic rays there. The cross-section of K$\alpha$ vacancies produced by protons differs from that of electrons or X-rays. Therefore, we expect that this processes can be distinguished from the analysis of the equivalent width of the iron line and time variations of the width can be predicted. The line intensity from the clouds depends on their distance from Sgr A${}^{\ast }$ and the coefficient of spacial diffusion near the Galactic center. We expect that in a few years the line intensity for the cloud G\,0.11$-$0.11 which is relatively close to Sgr A${}^{\ast }$ will decreases to the level $\lesssim$ 10% from its present value. For the cloud Sagittarius B2 (Sgr B2) the situation is more intricate. If the diffusion coefficient $D\gtrsim 10^{27}$ cm${}^2$ s${}^{-1}$ then the expected stationary flux should be about 10% of its level in 2000. In the opposite case the line intensity from Sgr B2 should drop down to zero because the protons do not reach the cloud.

PASJ accepted

References in corpus (27)

• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Stellar Processes Near the Massive Black Hole in the Galactic Center
• Discrete sources as the origin of the Galactic X-ray ridge emission
• XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*
• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• Nonthermal Emission from a Supernova Remnant in a Molecular Cloud
• Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
• Tidal Disruption of a Solar Type Star by a Super-Massive Black Hole
• Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
• Fading hard X-ray emission from the Galactic Centre molecular cloud Sgr B2
• Equivalent width, shape and proper motion of the iron fluorescent line emission from the molecular clouds as an indicator of the illuminating source X-ray flux history
• The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic Center Region: Cosmic Ray Particles
• Wild at Heart:-The Particle Astrophysics of the Galactic Centre
• The Dynamics of Molecular Material Within 15 pcs of the Galactic Center
• The Origin of X-ray Emission from a Galactic Center Molecular Cloud: Low Energy Cosmic Ray Electrons
• Cosmic-Ray Heating of Molecular Gas in the Nuclear Disk: Low Star Formation Efficiency
• Annihilation Emission from the Galactic Black Hole
• Discoveries of Diffuse Iron Line Sources from the Sgr B Region
• Spectral Study of the Galactic Ridge X-ray Emission with Suzaku
• A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole
• Discovery of K-Shell Emission Lines of Neutral Atoms in the Galactic Center Region
• Diffuse Gamma-ray Emission from the Galactic Center - A Multiple Energy Injection Model
• Cosmic ray ionization of the interstellar medium
• A past capture event at Sagittarius A* inferred from the fluorescent X-ray emission of Sagittarius B clouds
• Suzaku Observation Adjacent to the South End of the Radio Arc
• Nuclear Interaction Gamma-Ray Lines from the Galactic Center Region
• Origin of Thermal and Non-Thermal Hard X-ray Emission from the Galactic Center

Cited by in corpus (22)

• Nonthermal particles and photons in starburst regions and superbubbles
• Traces of past activity in the Galactic Centre
• Nonthermal X-rays from low-energy cosmic rays: Application to the 6.4 keV line emission from the Arches cluster region
• Galactic Center Research: Manifestations of the Central Black Hole
• Penetration of cosmic rays into dense molecular clouds: role of diffuse envelope
• Evidence for a neutral iron line generated by MeV protons from supernova remnants interacting with molecular clouds
• Diffuse X-Ray Sky in the Galactic Center
• High-energy Cosmic Ray production in X-ray Binary Jets
• The Fermi Bubble as a Source of Cosmic Rays in the Energy Range > 10E15 eV
• The Transition from Young to Middle-aged Supernova Remnants: Thermal and Nonthermal Aspects of SNR N132D
• Suzaku spectra of a Type II Supernova Remnant Kes 79
• Spectrum of Relativistic and Subrelativistic Cosmic Rays in the 100 pc Central Region
• NuSTAR Detection of Nonthermal Bremsstrahlung from the Supernova Remnant W49B
• The origin of the 6.4 keV line emission and H${}_2$ ionization in the diffuse molecular gas of the Galactic center region
• On the Origin of the 6.4 keV Line in the Galactic Center Region
• Neutral iron line in the supernova remnant IC 443 and implications for MeV cosmic rays
• Discovery of 6.4 keV line and soft X-ray emissions from G323.7$-$1.0 with Suzaku
• Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
• Time-Variability of equivalent width of 6.4 keV line from the Arches Complex: reflected X-rays or charged particles?
• Probing Cosmic Rays with Fe K$\alpha$ Line Structures Generated by Multiple Ionization Process
• Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region
• Nonthermal processes and particle acceleration in supernova remnants