Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3

Astronomy and Astrophysics – Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

11 pages, accepted for publication in ApJ

Scientific paper

10.1086/497584

X-ray absorption lines of highly-ionized species such as OVII at about zero redshift have been firmly detected in the spectra of several active galactic nuclei. However, the location of the absorbing gas remains a subject of debate. To separate the Galactic and extragalactic contributions to the absorption, we have obtained Chandra LETG-HRC and FUSE observations of the black hole X-ray binary LMC X--3. A joint analysis of the detected OVII and Ne IX Kalpha lines, together with the non-detection of the OVII Kbeta and OVIII Kalpha lines, gives the measurements of the temperature, velocity dispersion, and hot oxygen column density. The X-ray data also allow us to place a 95% confidence lower limit to the Ne/O ratio as 0.14. The OVII line centroid and its relative shift from the Galactic OI Kalpha absorption line, detected in the same observations, are inconsistent with the systemic velocity of LMC X--3 ($+310 {\rm km s^{-1}}$). The far-UV spectrum shows OVI absorption at Galactic velocities, but no OVI absorption is detected at the LMC velocity at $> 3\sigma$ significance. Both the nonthermal broadening and the decreasing scale height with the increasing ionization state further suggest an origin of the highly-ionized gas in a supernova-driven galactic fountain. In addition, we estimate the warm and hot electron column densities from our detected OVII Kalpha line in the LMC X--3 X-ray spectra and from the dispersion measure of a pulsar in the LMC vicinity. We then infer the O/H ratio of the gas to be $\gtrsim 8 \times 10^{-5}$, consistent with the chemically-enriched galactic fountain scenario. We conclude that the Galactic hot interstellar medium should in general substantially contribute to zero-redshift X-ray absorption lines in extragalactic sources.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3 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 Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3 will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-115660

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.