Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-05-18
Astronomy and Astrophysics
Astrophysics
5 pages, 4 figs, and 2 tables, accepted for publication in ApJ; references updated; match to the version of proofs
Scientific paper
The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of <= 200 pc) and/or a phenomenon related to energetic outflows from the Galactic center/bulge remains unclear. Here we report a comparative X-ray emission and absorption study of diffuse hot gas along the sight lines toward 3C 273 and Mrk 421, on and off the enhancement, but at similar Galactic latitudes. The diffuse 3/4-keV emission intensity, as estimated from the ROSAT All Sky Survey, is about three times higher toward 3C 273 than toward Mrk 421. Based on archival \chandra grating observations of these two AGNs, we detect X-ray absorption lines (e.g., OVII Kalpha, Kbeta, and OVIII Kalpha transitions at z~0) and find that the mean hot gas thermal and kinematic properties along the two sight lines are significantly different. By subtracting the foreground and background contribution, as determined along the Mrk 421 sight line, we isolate the net X-ray absorption and emission produced by the hot gas associated with the enhancement in the direction of 3C 273. From a joint analysis of these differential data sets, we obtain the temperature, dispersion velocity, and hydrogen column density as 2.0(1.6, 2.3)E6 K, 216(104,480) km/s, and 2.2(1.4, 4.1)E19 cm^{-2}, respectively (90% confidence intervals), assuming that the gas is approximately isothermal, solar in metal abundances, and equilibrium in collisional ionization. We also constrain the effective line-of-sight extent of the gas to be 3.4(1.0, 10.1) kpc, strongly suggesting that the enhancement most likely represents a Galactic central phenomenon.
Wang Daniel Q.
Yao Yangsen
No associations
LandOfFree
The Galactic Central Diffuse X-ray Enhancement: A Differential Absorption/Emission Analysis does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Galactic Central Diffuse X-ray Enhancement: A Differential Absorption/Emission Analysis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Galactic Central Diffuse X-ray Enhancement: A Differential Absorption/Emission Analysis will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-431036