Origin of the Galactic Diffuse X-ray Emission: Iron K-shell Line Diagnostics

Abstract

This paper reports detailed K-shell line profiles of iron (Fe) and nickel (Ni) of the Galactic Center X-ray Emission (GCXE), Galactic Bulge X-ray Emission (GBXE), Galactic Ridge X-ray Emission (GRXE), magnetic Cataclysmic Variables (mCVs), non-magnetic Cataclysmic Variables (non-mCVs), and coronally Active Binaries (ABs). For the study of the origin of the GCXE, GBXE, and GRXE, the spectral analysis is focused on equivalent widths of the Fe K$\alpha$, Fe He$\alpha$, and Fe Ly$\alpha$ lines. The global spectrum of the GBXE is reproduced by a combination of the mCVs, non-mCVs, and ABs spectra. On the other hand, the GRXE spectrum shows significant data excesses at the Fe K$\alpha$ and Fe He$\alpha$ line energies. This means that additional components other than mCVs, non-mCVs, and ABs are required, which have symbiotic phenomena of cold gas and very high-temperature plasma. The GCXE spectrum shows larger excesses than those found in the GRXE spectrum at all the K-shell lines of iron and nickel. Among them the largest ones are the Fe K$\alpha$, Fe He$\alpha$, Fe Ly$\alpha$, and Fe Ly$\beta$ lines. Together with the fact that the scale heights of the Fe K$\alpha$, Fe He$\alpha$, and Fe Ly$\alpha$ lines are similar to that of the central molecular zone (CMZ), the excess components would be related to high-energy activity in the extreme envelopment of the CMZ.

arXiv comment12 pages, 10 figures, 5 tables, published in ApJ

References in corpus (39)

• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• The Nuclear Bulge of the Galaxy. III. Large-Scale Physical Characteristics of Stars and Interstellar Matter
• Reproducibility of Non-X-ray Background for the X-ray Imaging Spectrometer aboard Suzaku
• Study of the X-Ray Background Spectrum and its Large-Scale Fluctuation with ASCA
• Discrete sources as the origin of the Galactic X-ray ridge emission
• Diffuse X-ray Emission in a Deep Chandra Image of the Galactic Center
• A Deep Chandra Catalog of X-ray Point Sources toward the Galactic Center
• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• X-ray luminosity function of faint point sources in the Milky Way
• Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
• Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy
• ASCA X-ray source catalogue in the Galactic Center region
• Fading hard X-ray emission from the Galactic Centre molecular cloud Sgr B2
• Chandra Deep X-ray Observation of a Typical Galactic Plane Region and Near-Infrared Identification
• ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy
• A Chandra Catalog of X-ray Sources in the Central 150 pc of the Galaxy
• The K-shell Line Distribution of Heavy Elements along the Galactic Plane Observed with Suzaku
• A study of X-ray flares - II. RS CVn type Binaries
• Deriving an X-ray luminosity function of dwarf novae based on parallax measurements
• Broad-band spectral analysis of the Galactic Ridge X-ray Emission
• The X-ray lightcurve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds
• Characteristics of Diffuse X-Ray Line Emission within 20 pc of the Galactic Center
• Fe Line Diagnostics of Cataclysmic Variables and Galactic Ridge X-ray Emission
• Discovery of the recombining plasma in the south of the Galactic center; a relic of the past Galactic center activity?
• Discoveries of Diffuse Iron Line Sources from the Sgr B Region
• Resolving the Galactic X-ray background
• Charge Exchange Spectra of Hydrogenic and He-like Iron
• Discovery of K-Shell Emission Lines of Neutral Atoms in the Galactic Center Region
• Dominance of Magnetic Cataclysmic Variables in the Resolved Galactic Ridge X-ray Emission of the Limiting Window
• Scale heights and equivalent widths of the iron K-shell lines in the Galactic diffuse X-ray emission
• Spectroscopy of Nine Cataclysmic Variable Stars
• Global Distribution of Fe K alpha Lines in the Galactic Center Region Observed with the Suzaku Satellite
• Suzaku Spectroscopy Study of Hard X-Ray Emission in the Arches Cluster
• Map of the Galaxy in the 6.7 keV emission line
• On the contribution of point sources to the Galactic ridge X-ray emission
• Low-luminosity X-ray sources and the Galactic ridge X-ray emission
• X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron Ka Line in the Sgr C Region
• BF Eridani: a cataclysmic variable with a massive white dwarf and an evolved secondary
• Number Density Distribution of Near-Infrared Sources on a Sub-Degree Scale in the Galactic Center: Comparison with the Fe XXV Ka Line at 6.7 keV

Cited by in corpus (20)

• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• Hard X-ray Cataclysmic Variables
• 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
• X-ray Detectability of Accreting Isolated Black Holes in Our Galaxy
• On the space density of X-ray selected cataclysmic variables
• Spitzer Infrared Spectrograph Observations of the Galactic Center: Quantifying the Extreme Ultraviolet/so ft X-ray fluxes
• The Galactic Bulge Diffuse Emission in Broad-Band X-rays with NuSTAR
• Study of the excess Fe XXV line emission in the central degrees of the Galactic centre using XMM-Newton data
• An Empirical Correlation of $T_{\max }$ - $M_{\mathrm{WD}}$ of Dwarf Novae and The Average White Dwarf Mass in Cataclysmic Variables in the Galactic Bulge
• The Fe Line Flux Ratio as a diagnostic of the maximum temperature and the white dwarf mass of Cataclysmic Variables
• X-ray spectra of Sgr A East and diffuse X-ray background near the Galactic center
• An XMM-Newton Study of the Mixed-Morphology Supernova Remnant G346.6-0.2
• Deep Near-infrared Imaging Observation of the Faint X-ray Point Sources Constituting the Galactic Bulge X-ray Emission
• X-ray emission from the mixed-morphology supernova remnant HB 9
• X-ray spectral and flux variability of the microquasar GRS 1758-258 on timescales from weeks to years
• Origin of the low-temperature plasma in the Galactic center X-ray emission
• Spectrum Composition of Galactic Center X-ray Emission with Point and Diffuse X-ray Sources
• High Energy Emission from the Galactic Center
• X-ray luminous late-type giants: an overlooked population contributing to the Galactic ridge iron line emission