Search for the warm-hot intergalactic medium around A 2744 using Suzaku

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Hattori , S , Ota , N , Zhang , Y-Y , Akamatsu , H & Finoguenov , A 2017 , ' Search for the warm-hot intergalactic medium around A 2744 using Suzaku ' , Publications of the Astronomical Society of Japan , vol. 69 , no. 3 , 39 .

Title: Search for the warm-hot intergalactic medium around A 2744 using Suzaku
Author: Hattori, Shiho; Ota, Naomi; Zhang, Yu-Ying; Akamatsu, Hiroki; Finoguenov, Alexis
Contributor organization: Department of Physics
Date: 2017-06
Language: eng
Number of pages: 10
Belongs to series: Publications of the Astronomical Society of Japan
ISSN: 0004-6264
Abstract: We present the results from Suzaku satellite observations of the surrounding region of a galaxy cluster, A 2744, at z = 0.3. To search for oxygen emission lines from the warm-hot intergalactic medium (WHIM), we analyzed X-ray spectra from two northeastern regions 2.2-3.3 and 3.3-4.4 Mpc from the center of the cluster, which offers the first test on the presence of a WHIM near the typical accretion shock radius (similar to 2 r(200)) predicted by hydrodynamical simulations. For the 2.2-3.3 Mpc region, the spectral fit significantly (99.2% significance) improved when we included O-VII and O-VIII lines in the spectralmodel. A comparable WHIM surface brightness was obtained in the 3.3-4.4 Mpc region and the redshift of the O-VIII line is consistent with z=0.3 with in errors. The present results support that the observed soft X-ray emission originated from the WHIM. However, considering both statistical and systematic uncertainties, OVIII detection in the northeast regions was marginal. The surface brightnesses of the O-VIII line in 10(-7) photons cm(-2) s(-1) arcmin(-2) for the 2.2-3.3 and 3.3-4.4 Mpc regions were measured to be 2.7 +/- 1.0 and 2.1 +/- 1.2, giving upper limits on the baryon overdensity of delta = 319(<442) and 284(<446), respectively. This is comparable with previous observations of cluster outskirts and their theoretical predictions. The future prospect for WHIM detection using the Athena X-IFU micro-calorimeter is briefly discussed here. In addition, we also derived the intracluster medium temperature distribution of A 2744 to detect a clear discontinuity at the location of the radio relic. This suggests that the cluster has undergone strong shock heating by mass accretion along the filament.
Subject: cosmology: observations
galaxies: clusters: individual (Abell 2744)
intergalactic medium
large-scale structure of universe
X-rays: galaxies: clusters
115 Astronomy, Space science
Peer reviewed: Yes
Rights: other
Usage restriction: openAccess
Self-archived version: acceptedVersion

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