Issue |
A&A
Volume 469, Number 3, July III 2007
|
|
---|---|---|
Page(s) | 861 - 872 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20077407 | |
Published online | 02 May 2007 |
The dynamical status of the galaxy cluster Abell 115*
1
Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain e-mail: rbarrena@iac.es
2
Fundación Galileo Galilei - INAF, C/Alvarez de Abreu 70, 38700 Santa Cruz de La Palma, Canary Islands, Spain
3
Dipartimento di Astronomia of the Università degli Studi di Trieste, via Tiepolo 11, 34131 Trieste, Italy
4
INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy
5
Centre for Astrophysics & Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia
Received:
5
March
2007
Accepted:
19
April
2007
Aims.We present the results of a new spectroscopic and
photometric survey of the hot, binary X-ray cluster A115 at
, containing a radio relic.
Methods.Our analysis is based on new spectroscopic data obtained at the Telescopio Nazionale Galileo for 115 galaxies and on new photometric data obtained at the Isaac Newton Telescope in a large field. We combine galaxy velocity and position information to select 85 galaxies recognized as cluster members, determine global dynamical properties and detect substructures.
Results.We find that A115 appears as a well isolated peak in the redshift space,
with a global line-of-sight (LOS) velocity dispersion km s-1. Our analysis confirms the
presence of two structures of cluster-type well recognizable in the
plane of the sky and shows that they differ of ~2000 km s-1in the
LOS velocity. The northern, high velocity subcluster (A115N) is
likely centred on the second brightest cluster galaxy (BCM-A,
coincident with radio source 3C28) and the northern X-ray peak. The
southern, low velocity subcluster (A115S) is likely centred on the
first brightest cluster galaxy (BCM-B) and the southern X-ray peak.
We estimate that A115S is slightly dynamically more important than
A115N having
= 900-1100 km s-1 vs.
= 750-850 km s-1. Moreover, we find evidence for two small groups at
low velocities. We estimate a global cluster virial mass of 2.2-3.5
1015
.
Conclusions.Our results agree with a pre-merging scenario where A115N
and A115S are colliding with a LOS impact velocity 1600 km s-1. The most likely solution to the
two-body problem suggests that the merging axis lies at ~20 degrees from the plane of the sky and that the cores will cross after ~0.1 Gyr. The radio relic with its largest dimension
perpendicular to the merging axis is likely connected to this merger.
Key words: galaxies: clusters: general / galaxies: clusters: individual: Abell 115 / galaxies: distances and redshifts / cosmology: observations
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.