Mass Profile of the Infall Region of the Abell 2199 Supercluster

Abstract

Using a redshift survey of 1323 galaxies (1092 new or remeasured) in a region of 95 deg2 centered on the nearby galaxy cluster Abell 2199, we analyze the supercluster containing A2199, A2197, and an X-ray group. The caustic technique accurately reproduces the true mass profiles of simulated simple superclusters (i.e., superclusters for which the virial mass of one cluster is 2–10 times the virial mass of all other clusters in the supercluster). We calculate the masses of the two main components of A2197 (A2197W and A2197E) by using archival X-ray observations and demonstrate that the A2199 supercluster is simple (the mass of A2199 is 5 and 12 times larger than A2197W and A2197E, respectively) and thus that the caustic technique should yield an accurate mass profile. The masses of A2199, A2197W, and A2197E within r500 (the radius within which the enclosed density is 500 times the critical density) are 22.0, 3.8, and 1.7 times 1013 h-1 M⊙, respectively. The mass profile is uncertain by ~30% within 3 h-1 Mpc and by a factor of 2 within 8 h-1 Mpc and is one of only a few for a supercluster on such large scale. Independent X-ray mass estimates agree with our results at all radii where they overlap. The mass profile strongly disagrees with an isothermal sphere profile but agrees with profiles suggested by simulations. We discuss the interplay of the supercluster dynamics and the dynamics of the bound subclusters. The agreement between the infall mass profile and other techniques shows that the caustic technique is surprisingly robust for simple superclusters.