Galactic X-ray surveys

We 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) approximate to (28.degrees5, 0.degrees0) 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.