2009ApJ...698.1879M

We compare the distribution of diffuse intracluster light (ICL) detected in the Virgo Cluster via broadband imaging with that inferred from searches for intracluster planetary nebulae (IPNe). We find a rough correspondence on large scales (∼100 kpc) between the two, but with very large scatter (∼1.3 mag/arcsec2). On smaller scales (1-10 kpc), the presence or absence of correlation is clearly dependent on the underlying surface brightness. On these scales, we find a correlation in regions of higher surface brightness (µ_V≲ 27) which are dominated by the halos of large galaxies such as M87, M86, and M84. In those cases, we are likely tracing PNe associated with galaxies rather than true IPNe. In true intracluster fields, at lower surface brightness, the correlation between luminosity and IPN candidates is much weaker. While a correlation between broadband light and IPNe is expected based on stellar populations, a variety of statistical, physical, and methodological effects can act to wash out this correlation and explain the lack of a strong correlation at lower surface brightness found here. A significant complication comes from the stochastic nature of the PN population combined with contamination of the IPN catalogs due to photometric errors and background emission line objects. If we attribute the lack of a strong observed correlation solely to the effects of contamination, our Monte Carlo analysis shows that our results are mostly consistent with a "IPNe-follow-light" model if the IPN catalogs are contaminated by ∼40%. Further complications arise from the line-of-sight depth of the Virgo and uncertainty in the stellar populations of the ICL, both of which may contribute to the slight systematic differences seen between the IPN-inferred surface brightnesses and those derived from our deep surface photometry.