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 those of a typical massive elliptical galaxy and is clearly associated with the BCG. The outer component is 10-40 times larger in scale, has similar to10 times the total luminosity of the inner component, and exhibits a steeper -r(e) relation than that of the elliptical fundamental plane. We interpret this outer component as a population of intracluster stars that trace the cluster potential. The two components are strongly aligned (\Deltatheta\ < 10 degrees) 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.