NuSTAR Observations of Abell 2163: Constraints on Non-thermal Emission

Abstract

Since the first non-thermal reports of inverse Compton (IC) emission from the intracluster medium (ICM) of galaxy clusters at hard X-ray energies, we have yet to unambiguously confirm IC emission in observations with newer facilities. RXTE detected IC emission in one of the hottest known clusters, Abell 2163 (A2163), a massive merging cluster with a giant radio halo--the presumed source of relativistic electrons IC scattering CMB photons to X-ray energies. The cluster's redshift (z~0.2) allows its thermal and non-thermal radio emission to fit NuSTARS's FOV, permitting a deep observation capable of confirming or ruling out the RXTE report. The IC flux provides constraints on the average magnetic field strength in a cluster. To determine the global diffuse IC emission in A2163, we fit its global NuSTAR spectrum with four models: single (1T) and two-temperature (2T), 1T+power law component (T+IC), and multi-temperature+power law (9T+IC). Each represent different characterizations of the thermal ICM emission, with power law components added to represent IC emission. We find the 3-30 keV spectrum can be described by purely thermal emission, with a global average temperature of kT = (11.8 $\pm$ 0.2) keV. The IC flux is constrained to $<$ $4.0$ $\times$ $10^{-12}$ $erg$ $s^{-1}$ $c{m}^{-2}$ using the 1T+IC model and $<$ $1.6$ $\times$ $10^{-12}$ $erg$ $s^{-1}$ $c{m}^{-2}$ with the more physical 9T+IC model, both to 90% confidence levels. Combining these limits with 1.4 GHz diffuse radio data from the VLA, we find the average magnetic field strength to be $>$ $0.22$$\mu$$G$ and $>$ $0.35$$\mu$$G$, respectively, providing the strongest constraints on these values in A2163 to date.

arXiv comment16 pages, 17 figures

References in corpus (20)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Calibration of X-ray absorption in our Galaxy
• Cluster Magnetic Fields
• An Accurate Flux Density Scale from 1 to 50 GHz
• Radio Halo and Relic Candidates from the NRAO VLA Sky Survey
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• Revisiting scaling relations for giant radio halos in galaxy clusters
• Chandra Temperature Maps for Galaxy Clusters with Radio Halos
• Hydrostatic mass profiles in X-COP galaxy clusters
• The giant radio halo in Abell 2163
• Measuring the dynamical state of Planck SZ-selected clusters: X-ray peak - BCG offset
• Spectral index maps of the radio halos in Abell 665 and Abell 2163
• ABELL 2163: Temperature, Mass, and Hydrostatic Equilibrium
• Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters
• A2163: Merger events in the hottest Abell galaxy cluster I. Dynamical analysis from optical data
• First measurement of cluster temperature using the thermal Sunyaev-Zeldovich effect
• Long RXTE Observations of A2163
• A2163: Merger events in the hottest Abell galaxy cluster II. Subcluster accretion with galaxy-gas separation
• Investigating the hard X-ray emission from the hottest Abell cluster A2163 with Suzaku

Cited by in corpus (7)

• Head-to-Toe Measurement of El Gordo: Improved Analysis of the Galaxy Cluster ACT-CL J0102-4915 with New Wide-field Hubble Space Telescope Imaging Data
• A Systematic Comparison of Galaxy Cluster Temperatures Measured with NuSTAR and Chandra
• The NuSTAR and Chandra view of CL 0217+70 and Its Tell-Tale Radio Halo
• Constraining the average magnetic field in galaxy clusters with current and upcoming CMB surveys
• The Merger Dynamics of the X-ray Emitting Plasma in Clusters of Galaxies
• Possible non-thermal origin of the hard X-ray emission in the merging galaxy cluster SPT-CL J2031-4037
• The NuSTAR View of Perseus: the ICM and a Peculiar Hard Excess