Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall

Details Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall

2010-01-21

arxiv.org/abs/1001.3692v2

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

11 pages, 6 figures; accepted for publication in the Astrophysical Journal; minor revisions to match the accepted version; con

Scientific paper

In a previous paper we reported a 3-sigma detection of an absorption line from the Warm-Hot Intergalactic Medium (WHIM) using the Chandra and XMM X-ray grating spectra of the blazar H2356-309, the sight-line of which intercepts the Sculptor Wall, a large-scale superstructure of galaxies at z ~ 0.03. To verify our initial detection, we obtained a deep (500 ks), follow-up exposure of H2356-309 as part of the Cycle-10 Chandra Large Project Program. From a joint analysis of the Cycle-10 and previous (Cycle-8) Chandra grating data we detect the redshifted OVII WHIM line at a significance level of 3.4-sigma, a substantial improvement over the 1.7-sigma level reported previously when using only the Cycle-8 data. The significance increases to 4.0-sigma when the existing XMM grating data are included in the analysis, thus confirming at higher significance the existence of the line at the redshift of the Sculptor Wall with an equivalent width of 28.5+/-10.5 mA (90% confidence). We obtain a 90% lower limit on the OVII column density of 0.8 10^16 cm^-2 and a 90% upper limit on the Doppler-b parameter of 460 km/s. Assuming the absorber is uniformly distributed throughout the ~ 15 Mpc portion of the blazar's sight-line that intercepts the Sculptor Wall, that the OVII column density is ~ 2 10^16 cm^-2 (corresponding to b > 150 km/s where the inferred column density is only weakly dependent on b), and that the oxygen abundance is 0.1 solar, we estimate a baryon over-density of ~ 30 for the WHIM, which is consistent with the peak of the WHIM mass fraction predicted by cosmological simulations. The clear detection of OVII absorption in the Sculptor Wall demonstrates the viability of using current observatories to study WHIM in the X-ray absorption spectra of blazars behind known large-scale structures.

Affiliated with

Also associated with

No associations

Rating

Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall 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 Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Confirmation of X-Ray Absorption by WHIM in the Sculptor Wall will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-248577