Simulations of the galaxy cluster CIZA J2242.8+5301-I. Thermal model and shock properties

Donnert, J. M. F.; Beck, Alexander M.; Dolag, Klaus und Rottgering, H. J. A. (2017): Simulations of the galaxy cluster CIZA J2242.8+5301-I. Thermal model and shock properties. In: Monthly Notices of the Royal Astronomical Society, Bd. 471, Nr. 4: S. 4587-4605

Abstract

The giant radio relic in CIZA J2242.8+5301 provides clear evidence of an Mpc-sized shock in a massive merging galaxy cluster. Here, we present idealized SPH hydrodynamical and collisionless dark matter simulations, aiming to find a model that is consistent with that large range of observations of this galaxy cluster. We first show that in the northern shock, the observed radio spectral index profile and integrated radio spectrum are consistent with the observed upstream X-ray temperature. Using simulations, we first find that only a cool-core versus non-cool-core merger can lead to the observed elongated X-ray morphology. We then carry out simulations for two merging clusters assuming a range of NFW and beta-model density profiles and hydrostatic equilibrium. We find a fiducial model that mimics the overall morphology of the shock structures, has a total mass of 1.6 x 1015M(circle dot) and a mass ratio of 1.76. For this model, the derived Mach number for the northern shock is 4.5. This is almost a factor 2 higher compared to the observational determination of the Mach number using X-ray observations or measurements of the radio injection spectral index. We could not find numerical models that both fit the X-ray properties and yielded such low Mach numbers. We discuss various ways of understanding this difference and argue that deep X-ray observations of CIZA J2242.8+5301 will be able to test our model and reconcile the differences.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0035-8711
• Sprache: Englisch