The double galaxy cluster Abell 2465 - II. Star formation in the cluster

TL;DR

This study examines star formation in the merging galaxy cluster Abell 2465 at redshift 0.245, revealing enhanced star formation rates and disturbed galaxy morphologies associated with the cluster's dynamic environment.

Contribution

It provides the first detailed analysis of star formation rates, spatial distribution, and galaxy morphologies in Abell 2465, highlighting the impact of cluster merging on star formation activity.

Findings

Star formation rates are above average for similar clusters.

Star forming galaxies are less concentrated in the cluster center.

Many Hα sources show disturbed or merging morphologies.

Abstract

We investigate the star formation rate and its location in the major merger cluster Abell 2465 at $z$ = 0.245. Optical properties of the cluster are described in Paper I. Measurements of the H$\alpha$ and infrared dust emission of galaxies in the cluster were made with an interference filter centred on the redshifted line at a wavelength of 817 nm and utilized data from the WISE satellite 12 $\mu$m band. Imaging in the Johnson $U$ and $B$ bands was obtained, and along with SDSS $u$ and $r$ was used to study the blue fraction, which appears enhanced, as a further signatures of star formation in the cluster. Star formation rates were calculated using standard calibrations. The total star formation rate normalized by the cluster mass, $\Sigma SFR/M_{cl}$ compared to compilations for other clusters indicate that the components of Abell 2465 lie above the mean $z$ and $M_{cl}$ relations, suggestive that interacting galaxy clusters have enhanced star formation. The projected radial distribution of the star forming galaxies does not follow a NFW profile and is relatively flat indicating that fewer star forming galaxies are in the cluster centre. The morphologies of the H$\alpha$ sources within $R_{200}$ for the cluster as a whole indicate that many are disturbed or merging, suggesting that a combination of merging or harassment is working.