Tramp Novae between Galaxies in the Fornax Cluster: Tracers of Intracluster Light

Abstract

We report the results of a survey for novae in and between the galaxies of the Fornax Cluster. Our survey provides strong evidence that intracluster novae exist and that they provide a useful, independent measure of the intracluster light in Fornax. We discovered six strong nova candidates in six distinct epochs spanning 11 yr from 1993 to 2004. The data were taken with the 4 m and the 1.5 m telescopes at Cerro Tololo Inter-American Observatory. The spatial distribution of the nova candidates is consistent with ~16%-41% of the total light in the cluster being in the intracluster light, based on the ratio of the number of novae we discovered in intracluster space over the total number of novae discovered plus a simple completeness correction factor. This estimate is consistent with independent measures of intracluster light in Fornax and Virgo using intracluster planetary nebulae. The accuracy of the intracluster light measurement improves with each survey epoch as more novae are discovered.