X-Ray Spectroscopy of Galactic Hot Gas along the PKS 2155-304 Sight Line
Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Wang, Q. Daniel; Yao, Yangsen; McCammon, Dan; Takei, Yoh; Yoshino, Tomotaka; Hagihara, Toshishige
Japan, United States
Abstract
We present a detailed spectroscopic study of the hot gas in the Galactic halo toward the direction of a blazer PKS 2155-304 (z = 0.117). The OVII and OVIII absorption lines were measured with the Low and High Energy Transmission Grating Spectrographs aboard Chandra, and the OVII, OVIII, and NeIX emission lines produced in an adjacent field of the PKS 2155-304 direction were observed with the X-ray Imaging Spectrometer aboard Suzaku. Assuming vertically exponential distributions of the gas temperature and the density, we performed a combined analysis of the absorption and emission data. The gas temperature and the density at the galactic plane were determined to be (2.5+0.6-0.3) × 106K and (1.4+0.5-0.4) × 10-3cm-3, and the scale heights of the gas temperature and density were 5.6+7.4-4.2 kpc and 2.3+0.9-0.8 kpc, respectively. These values are consistent with those obtained in the LMC X-3 direction.