Infrared Emission from the Nearby Cool Core Cluster Abell 2597

TL;DR

This study uses Spitzer observations to analyze the infrared emission from the central galaxy in Abell 2597, revealing significant star formation activity and dust properties in a nearby cool core galaxy cluster.

Contribution

First detailed infrared analysis of Abell 2597's BCG showing star formation rate and dust temperature, expanding understanding of cool core cluster galaxy properties.

Findings

Detected FIR excess indicating star formation of ~4-5 solar masses per year.

Dust in the galaxy is hotter than in similar higher-redshift BCGs.

FIR luminosity suggests a starburst or LIRG-like activity.

Abstract

We observed the brightest central galaxy (BCG) in the nearby (z=0.0821) cool core galaxy cluster Abell 2597 with the IRAC and MIPS instruments on board the Spitzer Space Telescope. The BCG was clearly detected in all Spitzer bandpasses, including the 70 and 160 micron wavebands. We report aperture photometry of the BCG. The spectral energy distribution exhibits a clear excess in the FIR over a Rayleigh-Jeans stellar tail, indicating a star formation rate of ~4-5 solar masses per year, consistent with the estimates from the UV and its H-alpha luminosity. This large FIR luminosity is consistent with that of a starburst or a Luminous Infrared Galaxy (LIRG), but together with a very massive and old population of stars that dominate the energy output of the galaxy. If the dust is at one temperature, the ratio of 70 to 160 micron fluxes indicate that the dust emitting mid-IR in this source is somewhat hotter than the dust emitting mid-IR in two BCGs at higher-redshift (z~0.2-0.3) and higher FIR luminosities observed earlier by Spitzer, in clusters Abell 1835 and Zwicky 3146.