A Systematic Comparison of Galaxy Cluster Temperatures Measured with NuSTAR and Chandra

Abstract

Temperature measurements of galaxy clusters are used to determine their masses, which in turn are used to determine cosmological parameters. However, systematic differences between the temperatures measured by different telescopes imply a significant source of systematic uncertainty on such mass estimates. We perform the first systematic comparison between cluster temperatures measured with Chandra and NuSTAR. This provides a useful contribution to the effort of cross-calibrating cluster temperatures due to the harder response of NuSTAR compared with most other observatories. We measure average temperatures for 8 clusters observed with NuSTAR and Chandra. We fit the NuSTAR spectra in a hard (3-10 keV) energy band, and the Chandra spectra in both the hard and a broad (0.6-9 keV) band. We fit a power-law cross-calibration model to the resulting temperatures. At a Chandra temperature of 10 keV, the average NuSTAR temperature was $(10.5\pm 3.7)\%$ and $(15.7\pm 4.6)\%$ lower than Chandra for the broad and hard band fits respectively. We explored the impact of systematics from background modelling and multiphase temperature structure of the clusters, and found that these did not affect our results. Our sample are primarily merging clusters with complex thermal structures so are not ideal calibration targets. However, given the harder response of NuSTAR it would be expected to measure a higher average temperature than Chandra for a non-isothermal cluster, so we interpret our measurement as a lower limit on the difference in temperatures between NuSTAR and Chandra.

12 pages plus appendices. Accepted for publication in MNRAS

References in corpus (7)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Images, structural properties and metal abundances of galaxy clusters observed with Chandra ACIS-I at 0.1<z<1.3
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• XMM-Newton and Chandra Cross Calibration Using HIFLUGCS Galaxy Clusters: Systematic Temperature Differences and Cosmological Impact
• Tracing the non-thermal pressure and hydrostatic bias in galaxy clusters
• Measuring $H_0$ using X-ray and SZ effect observations of dynamically relaxed galaxy clusters
• NuSTAR Observations of Abell 2163: Constraints on Non-thermal Emission

Cited by in corpus (10)

• Science objectives of the Einstein Probe mission
• The SRG/eROSITA All-Sky Survey: SRG/eROSITA cross-calibration with Chandra and XMM-Newton using galaxy cluster gas temperatures
• CHEX-MATE: CLUster Multi-Probes in Three Dimensions (CLUMP-3D), I. Gas Analysis Method using X-ray and Sunyaev-Zel'dovich Effect Data
• The effect of pressure-anisotropy-driven kinetic instabilities on magnetic field amplification in galaxy clusters
• Electron-Ion Equilibration in the Merging Galaxy Cluster A665
• Detection of pure warm-hot intergalactic medium emission from a $7.2$ Mpc long filament in the Shapley supercluster using X-ray spectroscopy
• Deep Chandra observations of PLCKG287.0+32.9: a clear detection of a shock front in a heated former cool core
• The clus model in SPEX: projection and resonant scattering effects on the iron abundance and temperature profiles of galaxy clusters
• Cross Calibration of Galaxy Cluster Temperatures Measured with NuSTAR, XMM-Newton, and Chandra
• The thermodynamic structure and large-scale structure filament in MACS J0717.5+3745