Spatial Distribution of the Galactic Center Diffuse X-Rays and the Spectra of the Brightest 6.4keV Clumps

TL;DR

This study uses Suzaku's high-resolution X-ray spectra to analyze the spatial distribution and spectral features of Galactic center diffuse X-rays, revealing asymmetries, clumpy structures, and variable features near Sgr A*.

Contribution

It provides the first spatially resolved spectroscopy of GCDX with detailed analysis of iron line emissions and their relation to continuum flux, offering insights into the diffuse and point source contributions.

Findings

6.4keV and 6.7keV iron lines are asymmetrically distributed.

Bright clumps exhibit temporal variability.

The combined iron line flux correlates well with the continuum flux.

Abstract

The high energy resolution and low background, particularly in the hard X-ray band, of the X-ray Imaging Spectrometer onboard Suzaku provide excellent spectra of the Galactic center diffuse X-rays (GCDX). This paper reports on the results of spatially resolved spectroscopy of GCDX. The most pronounced features of GCDX are the K-shell transition lines from neutral (FeI) and He-like (FeXXV) irons at energies of 6.4keV and 6.7keV, respectively. The fluxes of these lines are non-uniformly and asymmetrically distributed with respect to Sgr A*. The 6.4keV lines are particularly bright on the positive side of the Galactic longitude (east-side) with clumpy structures. A bright clump near the GC exhibits a time variability over a timescale of a few years. Neither the 6.4keV nor 6.7keV line flux shows close proportionality to the continuum flux (5--10keV band); the 6.4keV line shows excess on the high flux side, and vice versa for the 6.7keV line. On the other hand, the sum of the 6.4keV plus 6.7keV line fluxes with a ratio of 1:2 shows good proportionality to the continuum flux, and hence we phenomenologically decomposed the continuum flux of the GCDX into the 6.4keV- and 6.7keV-associated continuums with a flux ratio of 1:2. Based on these facts, we have tried to estimate the contribution of diffuse and integrated flux of point sources to the GCDX.