A Study of the Luminosity and Mass Functions of the Young IC 348 Cluster Using FLAMINGOS Wide-Field Near-Infrared Images

We present wide-field near-infrared (JHK) images of the young, 2 Myr IC 348cluster taken with FLAMINGOS. We use these new data to construct an infraredcensus of sources, which is sensitive enough to detect a 10 Mjup brown dwarfseen through an extinction of Av=7mag. We examine the cluster's structure andrelationship to the molecular cloud and construct the cluster's K bandluminosity function. Using our model luminosity function algorithm, we derivethe cluster's initial mass function throughout the stellar and substellarregimes and find that the IC 348 IMF is very similar to that found for theTrapezium Cluster with both cluster IMFs having a mode between 0.2 - 0.08 Msun.In particular we find that, similar to our results for the Trapezium, browndwarfs constitute only 1 in 4 of the sources in the IC 348 cluster. We showthat a modest secondary peak forms in the substellar IC 348 KLF, correspondingto the same mass range responsible for a similar KLF peak found in theTrapezium. We interpret this KLF peak as either evidence for a correspondingsecondary IMF peak at the deuterium burning limit, or as arising from a featurein the substellar mass-luminosity relation that is not predicted by currenttheoretical models. Lastly, we find that IC 348 displays radial variations ofits sub-solar (0.5 - 0.08 Msun) IMF on a parsec scale. Whatever mechanism thatis breaking the universality of the IMF on small spatial scales in IC 348 doesnot appear to be acting upon the brown dwarf population, whose relative sizedoes not vary with distance from the cluster center.Comment: 53 pages, 20 figures, AASTeX5.0. Color version of Figure 1 made available in jpg format. Figure(s) 2,3,5 are reduced in resolution. Accepted 14 Jan 2003 to the Astronomical Journa