We present a combined optical and X-ray analysis of the rich cluster Abell 1882 with the aim of identifying merging substructure and understanding the recent assembly history of this system .
Our optical data consist of spectra drawn from the Galaxy and Mass Assembly ( GAMA ) survey , which lends itself to this kind of detailed study thanks to its depth and high spectroscopic completeness .
We use 283 spectroscopically confirmed cluster members to detect and characterize substructure .
We complement the optical data with X-ray data taken with both Chandra and XMM .
Our analysis reveals that A1882 harbors two main components , A1882A and A1882B , which have a projected separation of \sim 2 Mpc and a line of sight velocity difference of v _ { los } \sim - 428 ^ { +187 } _ { -139 } { km s ^ { -1 } } .
The primary system , A1882A , has velocity dispersion \sigma _ { v } = 500 _ { -26 } ^ { +23 } { km s ^ { -1 } } and Chandra ( XMM ) temperature kT = 3.57 \pm 0.17 keV ( 3.31 ^ { +0.28 } _ { -0.27 } keV ) while the secondary , A1882B , has \sigma _ { v } = 457 ^ { +108 } _ { -101 } { km s ^ { -1 } } and Chandra ( XMM ) temperature kT = 2.39 \pm 0.28 keV ( 2.12 \pm 0.20 keV ) .
The optical and X-ray estimates for the masses of the two systems are consistent within the uncertainties and indicate that there is twice as much mass in A1882A ( M _ { 500 } = 1.5 - 1.9 \times 10 ^ { 14 } M _ { \odot } ) when compared with A1882B ( M _ { 500 } = 0.8 - 1.0 \times 10 ^ { 14 } M _ { \odot } ) .
We interpret the A1882A/A1882B system as being observed prior to a core passage .
Supporting this interpretation is the large projected separation of A1882A and A1882B and the dearth of evidence for a recent ( < 2 Gyr ) major interaction in the X-ray data .
Two-body analyses indicate that A1882A and A1882B form a bound system with bound incoming solutions strongly favored .
We compute blue fractions of f _ { b } = 0.28 \pm 0.09 and 0.18 \pm 0.07 for the spectroscopically confirmed member galaxies within r _ { 500 } of the centers of A1882A and A1882B , respectively .
These blue fractions do not differ significantly from the blue fraction measured from an ensemble of 20 clusters with similar mass and redshift .