The Double Galaxy Cluster Abell 2465 I. Basic Properties: Optical Imaging and Spectroscopy

Abstract

Optical imaging and spectroscopic observations of the z = 0.245 double galaxy cluster Abell 2465 are described. This object appears to be undergoing a major merger. It is a double X-ray source and is detected in the radio at 1.4 GHz. This paper investigates signatures of the interaction of the two components. Redshifts were measured to determine velocity dispersions and virial radii of each component. The technique of fuzzy clustering was used to assign membership weights to the galaxies in each clump. Using redshifts of 93 cluster members within 1.4 Mpc of the subcluster centres, the virial masses and anisotropy parameters are derived. 37% of the spectroscopically observed galaxies show emission lines and are predominantly star forming in the diagnostic diagram. No strong AGN sources were found. The emission line galaxies tend to lie between the two cluster centres with more near the SW clump. The luminosity functions of the two subclusters differ. The NE component is similar to many rich clusters, while the SW component has more faint galaxies. The NE clump's light profile follows a single NFW profile with c = 10 while the SW is better fit with an extended outer region and a compact inner core, consistent with available X-ray data indicating that the SW clump has a cooling core. The observed differences and properties of the two components of Abell 2465 are interpreted to have been caused by a collision 2-4 Gyr ago, after which they have moved apart and are now near their apocentres, although the start of a merger remains a possibility. The number of emission line galaxies gives weight to the idea that galaxy cluster collisions trigger star formation.

21 pages, 18 Figures Replaced typos, mostly in references To appear in MNRAS, Accepted 2010 December 16. Received 2010 December 15; in original form 2010 November 01

References in corpus (39)

• A direct empirical proof of the existence of dark matter
• K-corrections and filter transformations in the ultraviolet, optical, and near infrared
• Shocks and cold fronts in galaxy clusters
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Weak Gravitational Lensing with COSMOS: Galaxy Selection and Shape Measurements
• The impact of mergers on relaxed X-ray clusters - I. Dynamical evolution and emergent transient structures
• Revealing the properties of dark matter in the merging cluster MACSJ0025.4-1222
• Statistics of X-ray observables for the cooling-core and non-cooling core galaxy clusters
• The speed of the `bullet' in the merging galaxy cluster 1E0657-56
• Cluster Constraints on f(R) Gravity
• Giant Ringlike Radio Structures Around Galaxy Cluster Abell 3376
• Discovery of a Ringlike Dark Matter Structure in the Core of the Galaxy Cluster Cl 0024+17
• The Bullet Cluster 1E0657-558 evidence shows Modified Gravity in the absence of Dark Matter
• Setting UBVRI Photometric Zero-Points Using Sloan Digital Sky Survey ugriz Magnitudes
• Simulating the Bullet Cluster
• Double relics in Abell 2345 and Abell 1240: spectral index and polarization analysis
• The L_X--M relation of Clusters of Galaxies
• Chandra observation of two shock fronts in the merging galaxy cluster Abell 2146
• Dark Matter and Baryons in the Most X-ray Luminous and Merging Galaxy Cluster RX J1347.5-1145
• Low-Frequency study of two clusters of galaxies: A2744 and A2219
• The impact of mergers on relaxed X-ray clusters - III. Effects on compact cool cores
• Substructures in WINGS clusters
• How Rare is the Bullet Cluster?
• Galaxy Cluster Radio Relics in Adaptive Mesh Refinement Cosmological Simulations: Relic Properties and Scaling Relationships
• The Red-Sequence Luminosity Function in Galaxy Clusters since z~1
• Galaxy Activity in Merging Binary Galaxy Clusters
• Triggering of merger-induced starbursts by the tidal field of galaxy groups and clusters
• The collision velocity of the bullet cluster in conventional and modified dynamics
• A2163: Merger events in the hottest Abell galaxy cluster I. Dynamical analysis from optical data
• MOND plus classical neutrinos not enough for cluster lensing
• Cluster Abell 520: a perspective based on member galaxies. A cluster forming at the crossing of three filaments?
• Radio observations of the Horologium-Reticulum Supercluster -I. A3158: Excess star-forming galaxies in a merging cluster?
• Measurement of the dark matter velocity anisotropy in galaxy clusters
• Deep Herschel view of obscured star formation in the Bullet cluster
• Ages and Metallicities of Early-Type Void Galaxies from Line Strength Measurements
• Measuring the dark matter velocity anisotropy in galaxy clusters
• Testing the Newton second law in the regime of small accelerations
• Suzaku Observations of the Merging Cluster Abell 85: Temperature Map and Impact Direction
• Measurement of the dark matter velocity anisotropy profile in galaxy clusters

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