DRY MERGER RATE AND POST-MERGER FRACTION IN THE COMA CLUSTER CORE
- Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)
- Finnish Centre for Astronomy with ESO, University of Turku, Vaisalantie 20, Piikkio, FI-21500 (Finland)
- School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)
- Department of Astronomy, The University of Texas at Austin, Austin, TX 78712-1205 (United States)
We evaluate the dry merger activity in the Coma cluster, using a spectroscopically complete sample of 70 red-sequence (RS) galaxies, most of which (∼75%) are located within 0.2R{sub 200} (∼0.5 Mpc) from the cluster center, with data from the Coma Treasury Survey obtained with the Hubble Space Telescope. The fraction of close galaxy pairs in the sample is the proxy employed for the estimation of the merger activity. We identify 5 pairs and 1 triplet, enclosing a total of 13 galaxies, based on limits on projected separation and line-of-sight velocity difference. Of these systems, none show signs of ongoing interaction, and therefore we do not find any true mergers in our sample. This negative result sets a 1σ upper limit of 1.5% per Gyr for the major dry merger rate, consistent with the low rates expected in present-day clusters. Detailed examination of the images of all the RS galaxies in the sample reveals only one with low surface brightness features identifiable as the remnant of a past merger or interaction, implying a post-merger fraction below 2%.
- OSTI ID:
- 22518631
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 817; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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