Thermal X-Ray Iron Line Emission from the Galactic Center Black Hole Sagittarius A*

Abstract

We model thermal X-ray emission from the accreting supermassive black hole Sagittarius A* at the Galactic Center. For the region inside $1{.}^{\prime \prime }5$ of the center, we use a {generalized} radiatively inefficient accretion flow (RIAF) model, and for the region out to $10^{\prime \prime }$ we use published models of the ambient hot gas. We calculate the equivalent widths of Hydrogen-like and Helium-like emission lines of various elements, notably iron. We predict that a strong Helium-like iron line with an equivalent width $\sim 1$ keV should be emitted by both the external medium and the RIAF. The equivalent width in the external medium is sensitive to the metallicity $Z$ of the gas as well as the mean temperature. For reasonable choices of these parameters, the calculated results agree with Chandra's detection of an iron line with an equivalent width of 1.3 keV within $10^{\prime \prime }$. The emission from within $1{.}^{\prime \prime }5$ is not sensitive to the external temperature, but is sensitive to the density and, especially, temperature profile inside the Bondi radius. For the range of profiles we consider, we calculate the equivalent width of the iron line to be $\sim 0.6-1.5(Z/Z_{\odot })$ keV, where $Z_{\odot }$ is the solar metallicity. We present a new Chandra spectrum of the quiescent emission within $1{.}^{\prime \prime }5$ of Sgr A*. The measured equivalent width of the iron line is 0.7 keV. Although this measurement has a large uncertainty, it is consistent with our predictions, provided the metallicity of the gas is approximately solar.

23 pages, 9 figures. Accepted for publication in The Astrophysical Journal

References in corpus (30)

• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• Closest Star Seen Orbiting the Supermassive Black Hole at the Centre of the Milky Way
• Stellar Orbits Around the Galactic Center Black Hole
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• A Jet-ADAF model for Sgr A*
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• The Nature of the 10 Kilosecond X-ray Flare in Sgr A*
• The Proper Motion of SgrA*: I. First VLBA Results
• A Chandra Study of Sgr A East: A Supernova Remnant Regulating The Activity Of Our Galactic Center?
• A Deep Chandra Catalog of X-ray Point Sources toward the Galactic Center
• On The Nature of the Variable Infrared Emission from Sgr A*
• Galactic Centre stellar winds and Sgr A* accretion
• A Dynamical Model for Hot Gas in the Galactic Center
• Metallicity in the Galactic Center: The Arches cluster
• Hydrodynamical Accretion Onto Sgr A* From Distributed Point Sources
• An Accretion-Induced X-ray Flare in Sgr A*
• A Thermal Bremsstrahlung Model For the Quiescent X-ray Emission from Sagittarius A*
• The Zoo of X-ray sources in the Galactic Center Region: Observations with BeppoSAX
• Diffuse X-Rays from the Inner 3 Parsecs of the Galaxy
• Accretion of cool stellar winds on Sgr A*: another puzzle of the Galactic Centre?
• X-ray flares from Sgr A*: star-disk interactions?
• Synchrotron Radiation From Radiatively Inefficient Accretion Flow Simulations: Applications to Sgr A*
• The Cooling Flow to Accretion Flow Transition
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• Thermal X-Ray Line Emission from Accreting Black Holes
• The K-alpha complex of He-like iron with dielectronic satellites
• Galactic Extinction from Colors and Counts of Field Galaxies in WFPC2 Frames: An Application to GRB 970228

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