Possible non-thermal origin of the hard X-ray emission in the merging galaxy cluster SPT-CL J2031-4037

Abstract

Non-thermal emission from clusters of galaxies at the high-energy X-ray regime has been searched with various instruments, but the detection significance of this emission has yet been found to be either marginal or controversial. Taking advantage of NuSTAR's unique capability to focus X-rays in the hard energy band, we present a detailed analysis of 238 ks NuSTAR observations of the merging galaxy cluster SPT-CL J2031-4037, searching for non-thermal inverse Compton emission. Our spectral analysis of SPT-CL J2031-4037 shows a possibility that the hard X-ray emission of the cluster can be described by a non-thermal component, though we cannot completely rule out a purely thermal origin for this hard emission. Including the statistical and systematic uncertainties, our best model fit yields a 20-80 keV non-thermal flux of $3.93_{-1.10}^{+1.24}\times 10^{-12}$ erg s${}^{-1}$ cm${}^{-2}$. The estimated non-thermal flux is comparable to those found in other galaxy clusters using NuSTAR and other X-ray instruments. Using this non-thermal flux with the existing radio data of the cluster, we estimate a volume-averaged magnetic field strength in the range of around 0.1-0.2 $\mu$G.

arXiv comment10 pages, 10 figures, 4 tables. Accepted for publication in MNRAS

References in corpus (40)

• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release TGSS ADR1
• Cluster Magnetic Fields
• Galaxy Clusters Discovered via the Sunyaev-Zel'dovich Effect in the 2500-square-degree SPT-SZ survey
• The ROSAT-ESO Flux Limited X-ray (REFLEX) Galaxy Cluster Survey. V. The cluster catalogue
• Cosmic rays in galaxy clusters and their non-thermal emission
• Magnetic Field in Clusters of Galaxies
• Diffuse Radio Emission from Galaxy Clusters
• The Coma cluster magnetic field from Faraday rotation measures
• An SZ-selected sample of the most massive galaxy clusters in the 2500-square-degree South Pole Telescope survey
• Hard X-Ray Radiation in the Coma Cluster Spectrum
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
• The Growth of Cool Cores and Evolution of Cooling Properties in a Sample of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey
• Sloshing of the Magnetized Cool Gas in the Cores of Galaxy Clusters
• Sunyaev-Zel'dovich Cluster Profiles Measured with the South Pole Telescope
• Confirmation of non-thermal hard X-ray excess in the Coma cluster from two epoch observations
• Hard X-ray emission from the galaxy cluster A2256
• Nonthermal Bremsstrahlung and Hard X-ray Emission from Clusters of Galaxies
• Baryon Content in a Sample of 91 Galaxy Clusters Selected by the South Pole Telescope at 0.2 < z < 1.25
• Galaxy Clusters in the Swift/BAT era: Hard X-rays in the ICM
• High- and low energy nonthermal X-ray emission from the cluster of galaxies A 2199
• Results from a Second RXTE Observation of the Coma Cluster
• Nonthermal phenomena in clusters of galaxies
• A Suzaku Search for Non-thermal Emission at Hard X-ray Energies in the Coma Cluster
• Testing for X-ray-SZ Differences and Redshift Evolution in the X-ray Morphology of Galaxy Clusters
• Hard X-ray emission from the galaxy cluster A3667
• The BeppoSAX view of the hot cluster Abell 2319
• Long RXTE Observations of A2163
• A NuSTAR observation of the center of the Coma Cluster
• Galaxy Clusters in the Swift/BAT era II: 10 more Clusters detected above 15 keV
• Hard X-ray and radio observations of Abell 754
• Analysis and Interpretation of Hard X-ray Emission from the Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by RXTE
• A joint XMM-NuSTAR observation of the galaxy cluster Abell 523: constraints on Inverse Compton emission
• Diffuse radio emission in the galaxy cluster SPT-CL J2031-4037: a steep spectrum intermediate radio halo?
• Investigating the hard X-ray emission from the hottest Abell cluster A2163 with Suzaku
• The Swift BAT Perspective on Non-thermal Emission in HIFLUGCS Galaxy Clusters
• NuSTAR Observations of Abell 2163: Constraints on Non-thermal Emission
• A BeppoSax view of the Centaurus Cluster
• Spectral Analysis of RXTE Observations of A3667

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