A high coverage view of the thermodynamics and metal abundance in the outskirts of the nearby galaxy cluster Abell 2199

Abstract

We present a joint Suzaku and XMM-Newton analysis of the outskirts of the nearby galaxy cluster Abell 2199, the only nearby galaxy cluster to be observed with near complete azimuthal coverage with Suzaku. Using the XMM-Newton observations to correct for the effects of gas clumping, we find that the azimuthally averaged entropy profile in the outskirts follows a power law with a slope of 1.20 ± 0.23, statistically consistent with a slope of 1.1 predicted by non-radiative simulations for purely gravitational hierarchical structure formation. However, when divided into 10 sectors, the entropy shows significant azimuthal variation, with some sectors lying below the baseline level. The azimuthally averaged gas mass fraction is found to agree with the cosmic mean baryon fraction. The metal abundance in the outskirts is found to be consistent with being uniform in all directions and it has an average value of $0.29_{-0.03}^{+0.03}\, Z_{\odot }$, consistent with the gas accreting onto clusters being pre-enriched with metals.

Cluster outskirts and their connection to the cosmic web

“…10, right panel). The Suzaku metal measurements in the outskirts generally show the metal abundance to level out at around 0.3Z [9,48,10], using the abundance tables from [53]. This is consistent with models of early metal enrichment (black solid line in Fig.…”

“…This allowed full azimuthal coverage to be achieved, at the expense of the spatial resolution of the observed thermodynamic profiles. In only one case, for Abell 2199 [10], was a nearby cluster covered with very high azimuthal coverage.…”

“…Fig. 2 Results from large Suzaku Projects on the outskirts of the Perseus cluster [8] (left), the Virgo cluster [9] (center) and Abell 2199 [10] (right), reprinted with permission. Suzaku's low instrumental background allows the ICM temperature, density and entropy in the outskirts to be measured using spectral fitting.…”

Simulating nearly edge-on sloshing in the galaxy cluster Abell 2199

“…These masses are consistent with the scaling relations from Piffaretti et al (2011b) and Lovisari et al (2015). Likewise, the virial radius should be r 200 = 1.60 Mpc, and the gas fraction at r 200 should be f gas = 0.16 (both from Mirakhor & Walker 2020). Given this M 200 at redshift z = 0.03, the concentration of such a halo ought to be approximately c = 4.3 according to Duffy et al (2008).…”

“…The main observational constraints that need to be approximately satisfied are as follows. We use as reference the virial mass M 200 = (3.10 ± 0.25) × 10 14 M or M 500 = (2.41 ± 0.15) × 10 14 M from Mirakhor & Walker (2020); or still M 200 = (3.16 ± 0.48) × 10 14 M from Lee et al (2015). These masses are consistent with the scaling relations from Piffaretti et al (2011b) and Lovisari et al (2015).…”