Broad-band spectral analysis of the Galactic Ridge X-ray Emission

Abstract

Detailed spectral analysis of the Galactic X-ray background emission, or the Galactic Ridge X-ray Emission (GRXE), is presented. To study the origin of the emission, broad-band and high-quality GRXE spectra were produced from 18 pointing observations with Suzaku in the Galactic bulge region, with the total exposure of 1 Ms. The spectra were successfully fitted by a sum of two major spectral components; a spectral model of magnetic accreting white dwarfs with a mass of 0.66 (0.59-0.75) solar, and a softer optically-thin thermal emission with a plasma temperature of 1.2-1.5 keV which is attributable to coronal X-ray sources. When combined with previous studies which employed high spatial resolution of the Chandra satellite (e.g. Revnivtsev et al. 2009, Nature), the present spectroscopic result gives another strong support to a scenario that the GRXE is essentially an assembly of numerous discrete faint X-ray stars. The detected GRXE flux in the hard X-ray band was used to estimate the number density of the unresolved hard X-ray sources. When integrated over a luminosity range of ~10^30-10^34 erg/s, the result is consistent with a value which was reported previously by directly resolving faint point sources.

accepted for publication in ApJ

References in corpus (5)

• White Dwarf Mass Distribution in the SDSS
• Discrete sources as the origin of the Galactic X-ray ridge emission
• A Catalog of X-ray Point Sources from Two Megaseconds of Chandra Observations of the Galactic Center
• Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare though Sodium-like Ions
• Hard X-ray emission from the Galactic ridge

Cited by in corpus (43)

• Magnetic White Dwarfs
• X-ray Emissions from Accreting White Dwarfs: a Review
• (Almost) Closing the $\nu$MSM Sterile Neutrino Dark Matter Window with NuSTAR
• NuSTAR Tests of Sterile-Neutrino Dark Matter: New Galactic Bulge Observations and Combined Impact
• The K-shell Line Distribution of Heavy Elements along the Galactic Plane Observed with Suzaku
• Hard X-ray view on intermediate polars in the Gaia era
• Traces of past activity in the Galactic Centre
• Evidence for intermediate polars as the origin of the Galactic Center hard X-ray emission
• NuSTAR Hard X-ray Survey of the Galactic Center Region II: X-ray Point Sources
• Fe Line Diagnostics of Cataclysmic Variables and Galactic Ridge X-ray Emission
• X-ray Luminosities of Optically-Selected Cataclysmic Variables and Application to the Galactic Ridge X-ray Emission
• Dominance of Magnetic Cataclysmic Variables in the Resolved Galactic Ridge X-ray Emission of the Limiting Window
• Diffuse X-Ray Sky in the Galactic Center
• Origin of the Galactic Diffuse X-ray Emission: Iron K-shell Line Diagnostics
• X-ray polarization evidence for a 200 years-old flare of Sgr A${}^{\ast }$
• XMM-Newton observations of the Galactic Centre Region - I: The distribution of low-luminosity X-ray sources
• INTEGRAL view on Cataclysmic Variables and Symbiotic Binaries
• Low-luminosity X-ray sources and the Galactic ridge X-ray emission
• Measuring the masses of Intermediate Polars with NuSTAR: V709 Cas, NY Lup and V1223 Sgr
• XMM-Newton observations of the Galactic Centre Region - II: The soft thermal emission
• The Galactic Bulge Diffuse Emission in Broad-Band X-rays with NuSTAR
• NuSTAR observations of the supernova remnant RX J1713.7$-$3946
• The NuSTAR Hard X-ray Survey of the Norma Arm Region
• XMM-Newton observations of the non-thermal supernova remnant HESS J1731-347 (G353.6-0.7)
• The Galactic plane at faint X-ray fluxes - II. Stacked X-ray spectra of a sample of serendipitous XMM-Newton sources
• 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
• Suzaku observations of the hard X-ray spectrum of Vela Jr
• An XMM-Newton Study of the Mixed-Morphology Supernova Remnant G346.6-0.2
• 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
• Discovery of periodicities in two highly variable intermediate polars towards the Galactic Center
• Classifying IGR J15038-6021 as a magnetic CV with a massive white dwarf
• Deep Near-infrared Imaging Observation of the Faint X-ray Point Sources Constituting the Galactic Bulge X-ray Emission
• Prospects for IXPE and eXTP polarimetric archaeology of the reflection nebulae in the Galactic center
• Broad Observational Perspectives Achieved by the Accreting White Dwarf Sciences in the XMM-Newton and Chandra Eras
• X-Ray Emission from the Galactic Supernova Remnant G12.0-0.1
• Evidence for GeV Cosmic Rays from White Dwarfs in the Local Cosmic Ray Spectra and in the Gamma-ray Emissivity of the Inner Galaxy
• The properties of the Galactic Hard X-Ray and soft gamma-ray Background based on 20 years of INTEGRAL/IBIS observations
• Spectrum Composition of Galactic Center X-ray Emission with Point and Diffuse X-ray Sources
• Iron emission line from the spiral galaxy M101
• Diffuse Hot Plasma in the Interstellar Medium and Galactic Outflows
• High Energy Emission from the Galactic Center
• X-ray luminous late-type giants: an overlooked population contributing to the Galactic ridge iron line emission
• X-ray emission of the Nuclear Stellar Disk as seen by SRG/ART-XC