GALAXY AND MASS ASSEMBLY (GAMA): WITNESSING THE ASSEMBLY OF THE CLUSTER ABELL 1882

Journal Article · Thu Aug 01 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/772/2/104· OSTI ID:22121810

Owers, M. S.; Bauer, A. E.; Cluver, M. E.; Hopkins, A. M.; Lara-Lopez, M. A. ^[1]; Baldry, I. K. ^[2]; Bland-Hawthorn, J.; Pimbblet, K. A. ^[3]; Brown, M. J. I. ^[4]; Colless, M.; Robotham, A. S. G. ^[5]; Driver, S. P. ^[6]; Edge, A. C. ^[7]; Van Kampen, E. ^[8]; Liske, J.; Loveday, J. ^[9]

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1. Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)
2. Astrophysics Research Institute, Liverpool John Moores University, Liverpool (United Kingdom)
3. Sydney Institute for Astronomy, School of Physics A28, University of Sydney, Sydney, NSW 2006 (Australia)
4. School of Physics, Monash University, Clayton, Vic. 3800 (Australia)
5. Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia)
6. School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom)
7. Institute of Computational Cosmology, Durham University, Durham DH1 3LE (United Kingdom)
8. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
9. Astronomy Center, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom)

We present a combined optical and X-ray analysis of the rich cluster ABELL 1882 (A1882) 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 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 {approx}2 Mpc and a line of sight velocity difference of v{sub los}{approx}-428{sup +187}{sub -139} km s{sup -1}. The primary system, A1882A, has velocity dispersion {sigma}{sub v}=500{sub -26}{sup +23} km s{sup -1} and Chandra (XMM) temperature kT = 3.57 {+-} 0.17 keV (3.31{sup +0.28}{sub -0.27} keV) while the secondary, A1882B, has {sigma}{sub v}=457{sup +108}{sub -101} km s{sup -1} and Chandra (XMM) temperature kT = 2.39 {+-} 0.28 keV (2.12 {+-} 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{sub 500} = 1.5-1.9 Multiplication-Sign 10{sup 14} M{sub Sun }) when compared with A1882B (M{sub 500} = 0.8-1.0 Multiplication-Sign 10{sup 14} M{sub Sun }). 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{sub b} = 0.28 {+-} 0.09 and 0.18 {+-} 0.07 for the spectroscopically confirmed member galaxies within r{sub 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.

• OSTI ID: 22121810
• Journal Information: Astrophysical Journal, Vol. 772, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
GALAXY CLUSTERS
KEV RANGE
MASS
RED SHIFT
SPECTRA
TWO-BODY PROBLEM
VELOCITY
X RADIATION