Search for WHIM around A2744 using Suzaku

Abstract

We present the results from the Suzaku satellite of the surrounding region of a galaxy cluster, A2744, at $z=0.3$. To search for oxygen emission lines from the warm-hot intergalactic medium (WHIM), we analyzed X-ray spectra from two northeast 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 ($\sim 2r_{200}$) predicted by hydrodynamical simulations. For the 2.2-3.3 Mpc region, the spectral fit significantly (99.2% significance) improved when we include OVII and OVIII lines in the spectral model. A comparable WHIM surface brightness was obtained in the 3.3-4.4 Mpc region and the redshift of OVIII line is consistent with $z=0.3$ within 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 brightness of the OVIII line in $10^{-7}\mathrm{photons}\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}\mathrm{arcmi}{\mathrm{n}}^{-2}$ was measured to be $2.7\pm 1.0$, $2.1\pm 1.2$ for the 2.2-3.3, 3.3-4.4 Mpc regions, giving the upper limit on the baryon overdensity of $\delta =319(<443)$, $283(<446)$, 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 ICM temperature distribution of A2744 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.

9 pages, 6 figures, PASJ accepted

References in corpus (8)

• The Search for the Missing Baryons at Low Redshift
• Warm-hot baryons comprise 5-10 per cent of filaments in the cosmic web
• Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223
• Mass Accretion and its Effects on the Self-Similarity of Gas Profiles in the Outskirts of Galaxy Clusters
• Low-Frequency study of two clusters of galaxies: A2744 and A2219
• A shock front at the radio relic of Abell 2744
• Flaming, bright galaxies along the filaments of A2744
• Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

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• X-ray emission from cosmic web filaments in SRG/eROSITA data
• Wide-Field Optical Spectroscopy of Abell 133: A Search for Filaments Reported in X-ray Observations
• The eROSITA view of the Abell 3391/95 field: Cluster Outskirts and Filaments
• A VLT/MUSE galaxy survey towards QSO Q1410: looking for a WHIM traced by BLAs in inter-cluster filaments
• A shock near the virial radius of the Perseus Cluster
• Discovery of large scale shock fronts correlated with the radio halo and radio relic in the A2163 galaxy cluster
• A Semi-Analytical Model for the Formation and Evolution of Radio Relics in Galaxy Clusters
• Tracing gaseous filaments connected to galaxy clusters: the case study of Abell 2744
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