AN X-RAY WHIM METAL ABSORBER FROM A Mpc-SCALE EMPTY REGION OF SPACE

作者：Zappacosta L^*; Nicastro F; Krongold Y; Maiolino R

来源：Astrophysical Journal, 2012, 753(2): 137.

DOI：10.1088/0004-637X/753/2/137

• BL Lacertae objects: individual (H 2356-309)
• intergalactic medium
• large-scale structure of universe
• quasars: absorption lines
• techniques: spectroscopic
• X-rays: galaxies: clusters

We report a detection of an absorption line at similar to 44.8 angstrom in a %26gt; 500 ks Chandra HRC-S/LETG X-ray grating spectrum of the blazar H 2356-309. This line can be identified as intervening Cv-K alpha absorption, at z approximate to 0.112, produced by a warm (log T = 5.1 K) intergalactic absorber. The feature is significant at a 2.9 sigma level (accounting for the number of independent redshift trials). We estimate an equivalent hydrogen column density of log N-H = 19.05(Z/Z(circle dot))(-1) cm(-2). Unlike other previously reported FUV/X-ray metal detections of warm-hot intergalactic medium (WHIM), this C v absorber lies in a region with locally low galaxy density, at similar to 2.2 Mpc from the closest galaxy at that redshift, and therefore is unlikely to be associated with an extended galactic halo. We instead tentatively identify this absorber with an intervening WHIM filament possibly permeating a large-scale, 30 Mpc extended, structure of galaxies whose redshift centroid, within a cylinder of 7.5 Mpc radius centered on the line of sight to H 2356-309, is marginally consistent (at a 1.8 sigma level) with the redshift of the absorber.

• 出版日期2012-7-10