Suzaku observations of X-ray excess emission in the cluster of galaxies A3112

TL;DR

This study uses Suzaku X-ray data to confirm the presence of excess emission in galaxy cluster A3112, exploring its thermal and non-thermal origins and modeling the emission with advanced differential emission measure models.

Contribution

It provides new Suzaku observations confirming excess X-ray emission in A3112 and evaluates its thermal and non-thermal origins using DEM models.

Findings

Excess emission is confirmed independent of background and calibration uncertainties.

Thermal and non-thermal models fit the data similarly, leaving the origin ambiguous.

DEM models yield consistent temperature estimates around 4.7 keV.

Abstract

We analysed the Suzaku XIS1 data of the A3112 cluster of galaxies in order to examine the X-ray excess emission in this cluster reported earlier with the XMM-Newton and Chandra satellites. The best-fit temperature of the intracluster gas depends strongly on the choice of the energy band used for the spectral analysis. This proves the existence of excess emission component in addition to the single-temperature MEKAL in A3112. We showed that this effect is not an artifact due to uncertainties of the background modeling, instrument calibration or the amount of Galactic absorption. Neither does the PSF scatter of the emission from the cool core nor the projection of the cool gas in the cluster outskirts produce the effect. Finally we modeled the excess emission either by using an additional MEKAL or powerlaw component. Due to the small differencies between thermal and non-thermal model we can not rule out the non-thermal origin of the excess emission based on the goodness of the fit. Assuming that it has a thermal origin, we further examined the Differential Emission Measure (DEM) models. We utilised two different DEM models, a Gaussian differential emission measure distribution (GDEM) and WDEM model, where the emission measure of a number of thermal components is distributed as a truncated power law. The best-fit XIS1 MEKAL temperature for the 0.4-7.0 keV band is 4.7+-0.1 keV, consistent with that obtained using GDEM and WDEM models.