Multi-Band Analysis of Abell 2255

TL;DR

This study analyzes X-ray data of galaxy cluster Abell 2255 to identify point sources and their optical counterparts, revealing increased galaxy activity at the outskirts likely due to environmental effects.

Contribution

First detailed multi-band X-ray and optical analysis of Abell 2255's outskirts, linking X-ray sources to galaxy activity and environmental influences.

Findings

Detected 11 X-ray point sources in Abell 2255 outskirts.

Cluster source density is four times higher than the field at a specific flux level.

Increased galaxy activity likely triggered by environmental factors at the cluster edge.

Abstract

We analyzed the data for the nearby cluster of galaxies Abell 2255 from archival XMM-Newton observations in order to search for the properties of X-ray point like structures in the outskirts. 11 point-like X-ray emission is detected. Detected X-ray sources are then observed with the 1.5 meter RTT-150 at Turkish National Observatory for possible optical counterparts. The cluster field is covered through 5 ANDOR photometer pointings. 3 sources have no optical follow-ups. 2 QSOs and 1 star are observed from the field. For 4 sources we have obtained the corresponding redhifts. The cumulative log(N)-log(S) is studied and the cluster source number is calculated to be 4 times higher than the field at Fx~10E-13 ergs cm-2 s-1. This phenomenon is interpreted as increased galaxy activity as they first encounter high density ICM environment at the cluster outskirt. We suggest that X-ray emission is triggered by either increased accretion onto LMXBs, fueling of AGNs and/or awakening of BHs.