Non-thermal emission in the core of Perseus: results from a long XMM-Newton observation

TL;DR

This study uses a long XMM-Newton observation to investigate non-thermal X-ray emission in the Perseus cluster core, finding it weaker than previous claims and discussing implications for magnetic field estimates and future detection prospects.

Contribution

It provides a detailed analysis of non-thermal emission in Perseus with improved calibration, challenging earlier Chandra results and setting constraints for future observations.

Findings

Non-thermal emission surface brightness is less than 5x10^-16 erg cm^-2s^-1arcsec^-2.

Discrepancies with Chandra are likely due to calibration issues.

Magnetic field estimates are consistent with other methods.

Abstract

We employ a long XMM-Newton observation of the core of the Perseus cluster to validate claims of a non-thermal component discovered with Chandra. From a meticulous analysis of our dataset, which includes a detailed treatment of systematic errors, we find the 2-10 keV surface brightness of the non-thermal component to be smaller than about 5x10^-16 erg cm^-2s^-1arcsec^-2. The most likely explanation for the discrepancy between the XMM-Newton and Chandra estimates is a problem in the effective area calibration of the latter. Our EPIC based magnetic field lower limits are not in disagreement with Faraday rotation measure estimates on a few cool cores and with a minimum energy estimate on Perseus. In the not too distant future Simbol-X may allow detection of non-thermal components with intensities more than 10 times smaller than those that can be measured with EPIC; nonetheless even the exquisite sensitivity within reach for Simbol-X might be insufficient to detect the IC emission from Perseus.