An X-ray WHIM metal absorber from a Mpc-scale empty region of space

Abstract

We report a detection of an absorption line at ~44.8 Å in a > 500 ks Chandra HRC-S/LETG X-ray grating spectrum of the blazar H 2356-309. This line can be identified as intervening CV-Kα absorption, at z\approx0.112, produced by a warm (log T = 5.1 K) intergalactic absorber. The feature is significant at a 2.9σ level (accounting for the number of independent redshift trials). We estimate an equivalent hydrogen column density of log N_H=19.05 (Z/Zsun)^-1 cm^-2. Unlike other previously reported FUV/X-ray metal detections of warm-hot intergalactic medium (WHIM), this CV absorber lies in a region with locally low galaxy density, at ~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 Warm-Hot Intergalactic Medium 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 1.8σ level) with the redshift of the absorber.

ApJ accepted, 6 pages, 3 figures

References in corpus (5)

• A High-Resolution Survey of Low-Redshift QSO Absorption Lines: Statistics and Physical Conditions of O VI Absorbers
• Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223
• FUV and X-ray absorption in the Warm-Hot Intergalactic Medium
• Detecting the warm-hot intergalactic medium through X-ray absorption lines
• Discovery of a large-scale galaxy filament near a candidate intergalactic X-ray absorption system

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• Probing the anisotropy of the Milky Way gaseous halo: Sight-lines toward Mrk 421 and PKS2155-304
• Diffuse Low-Ionization Gas in the Galactic Halo Casts Doubts on $z\simeq 0.03$ WHIM Detections
• Warm-hot gas in groups and galaxies toward H2356-309
• An R-matrix with pseudo-state (RMPS) approach to the single photon double ionization and excitation of the He-like Li${}^{+}$ ion
• A Relativistic Equation-of-motion Coupled-Cluster Investigation of the Trends of Single and Double Ionization Potentials in the He and Be Isoelectronic Systems