Bulletin of the Astronomical Society of India
Yuvraj Harsha Sreedhar1,*
1University of Vienna, Institute of Astronomy, Türkenschanzstraße 17, A-1180 Vienna, Austria
Received: April 24 2014 | Accepted: September 30 2014
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Red sequence galaxies form with an intense burst of star formation in the
early universe to evolve passively into massive, metal rich, old galaxies at z ~ 0. But
Abell 1314 (z=0.034) is found to host almost all red sequence galaxy members – identified
using the mz index, classified using the Principle Component Analysis technique
and SDSS colour correlations – some of which show properties of low-mass, star forming,
and metal rich galaxies. The variably spread Intra-Cluster Medium (ICM) near the
core forms a vital part in influencing the evolution of these members. To study their
evolution, I correlated dierent parameters of the rest-frame narrowband photometry
and the derived luminosity-weighted mean Single Stellar Population model ages and
metallicities.
The study finds the member galaxies evolve dierently in three dierent sections
of the cluster: 1. the region of ≤ 200 kpc hosts passively evolving old, massive
systems which accumulate mass by dry, minor mergers, 2. the zone between 200-500
kpc shows stripped systems (or in the process of being gas stripped) by ram pressure
with moderate star formation history, 3. the outer regions (≤ 500 kpc) show low-mass
red objects with blue, star forming Butcher-Oemler galaxy like colours. This sort of
environmental condition is known to harbour hybrid systems, like, the pseudo bulges,
blue sequence E/S0 and Butcher-Oemler like satellite cluster galaxies. Overall, the
cluster is found to be poor, quiescent with galaxies to have formed by the monolithic
structure formation in the early universe and are now evolving with mergers and gas
stripping processes by ram pressure.
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Keywords : galaxies: formation – galaxies: evolution – galaxies: clusters: individual: A1314 – galaxies: fundamental parameters (classification, colours, luminosities, masses, radii, etc.) – galaxies: interactions – galaxies: photometry