CONFIRMATION OF X-RAY ABSORPTION BY WARM-HOT INTERGALACTIC MEDIUM IN THE SCULPTOR WALL

Journal Article · Mon May 10 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/2/1715· OSTI ID:21448791

Taotao, Fang; Buote, David A; Humphrey, Philip J; Gastaldello, Fabio ^[1]; Canizares, Claude R ^[2]; Zappacosta, Luca ^[3]; Maiolino, Roberto ^[4]; Tagliaferri, Gianpiero ^[5]

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1. Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States)
2. Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
3. INAF-Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143 Trieste (Italy)
4. INAF-Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Roma (Italy)
5. INAF-Osservatorio Astronomico di Brera, Via Bianchi, 46, 23807 Merate (Italy)

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 {approx} 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 O VII 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 O VII column density of 0.8 x 10{sup 16} cm{sup -2} and a 90% upper limit on the Doppler b parameter of 460 km s{sup -1}. Assuming the absorber is uniformly distributed throughout the {approx}15 Mpc portion of the blazar's sight line that intercepts the Sculptor Wall, that the O VII column density is {approx}2 x 10{sup 16} cm{sup -2} (corresponding to b {approx_gt} 150 km {sup -1} 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 {approx}30 for the WHIM, which is consistent with the peak of the WHIM mass fraction predicted by cosmological simulations. The clear detection of O VII 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.

• OSTI ID: 21448791
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ABUNDANCE
BARYONS
BL LACERTAE OBJECTS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
GALAXIES
HADRONS
IONIZING RADIATIONS
QUASARS
RADIATIONS
RED SHIFT
SIMULATION
SORPTION
SPECTRA
UNIVERSE
X RADIATION
X-RAY GALAXIES
X-RAY SPECTRA