Galactic X‐ray surveys

Abstract

AbstractWe review highlights of the results obtained from recent Galactic X‐ray survey observations, in particular ASCA Galactic center and plane surveys and our Chandra deep survey on the (l, b) ≈ (28°.5, 0°.0) region. Strong hard X‐ray diffuse components are observed from Galactic ridge, center and bulge, and they have both thermal and non‐thermal spectral components. Dozens of discrete and extended sources have been discovered on the Galactic plane, which also indicate thermal and/or non‐thermal X‐ray energy spectra. They are often associated with radio sources and are considered to be SNR candidates. Most of the hard X‐ray point sources in the outer part of the Galactic plane are considered to be background AGNs, while fraction of the Galactic hard X‐ray sources (such as quiescent dwarf novae) increases toward the Galactic center. Most of the soft X‐ray sources on the Galactic plane are presumably nearby active stars.