Paper detail

Intracluster Light in Nearby Galaxy Clusters: Relationship to the Halos of Brightest Cluster Galaxies

We present a detailed analysis of the surface brightness distribution of the brightest cluster galaxy (BCG) in each of 24 galaxy clusters at 0.03<z<0.13. We use two-dimensional profile fitting to model the surface brightness out to r=300 kpc for each BCG, comparing r^{1/4}, r^{1/n}, and double r^{1/4} models. We obtain statistically superior fits using a two component model consisting of a pair of r^{1/4} profiles with independent scale lengths, ellipticities, and orientations. The two component model can simply reproduce the observed position angle and ellipticity gradients, which cannot generally be explained purely by triaxiality. The inner component of our two component model has properties similar to a typical massive elliptical galaxy and is clearly associated with the BCG. The outer component is 10-40 times larger in scale, has ~10 times the total luminosity of the inner component, and exhibits a steeper <μ>-r_e relation than that of the elliptical fundamental plane. We interpret this outer component as a population of intracluster stars tracing the cluster potential. The two components are strongly aligned (|Δθ|<10\degr) in roughly 40% of the clusters. When they are not aligned, the components tend toward high degrees of misalignment, suggesting that accretion of infalling material may change the orientation of some BCGs for a time. The extent of the outer component and its similar elongation to published cluster galaxy distributions indicates that the evolution of the intracluster light is tied to the cluster as a whole rather than to the BCG.