2013MNRAS.431..554R

Super star clusters (SSCs) are typically found in interacting galaxies and trace an extreme form of star formation. We present a K-band study of SSC candidates in a sample of local luminous infrared galaxies (LIRGs) using two adaptive optics instruments: the Very Large Telescope's Nasmyth Adaptive Optics System-COude Near Infrared CAmera (NACO) and Gemini's ALTtitude conjugate Adaptive optics for the InfraRed (ALTAIR)/Near InfraRed Imager and Spectrometer (NIRI). In addition to facilitating SSC detections in obscured environments, this work introduces SSC studies in hosts with higher star-formation rates (SFRs) than most previous studies. We find that the luminosity functions (LFs) of the clusters are reasonably well-fitted by a single power law with values of the index α ranging between 1.5 and 2.4 with an average value of α ~ 1.9. This value appears to be less steep than the average α ~ 2.2 in normal spiral galaxies. Due to the host galaxy distances involved (median DL ∼ 70 Mpc), blending effects have to be taken into account and are investigated using Monte Carlo simulations of blending effects for LFs and a photometric SSC analysis of the well-studied Antenna system, which is artificially redshifted to the distance of our sample. While blending tends to flatten LFs, our analyses show that Δα is less than ∼ 0.1 in our sample. The simulations also show that in the luminosity range MK < -13 considered in this work, the extracted SSC luminosities are generally dominated by a single dominant star cluster rather than several knots of star formation. We present resolution- and distance-dependent SSC surface-density confusion limits and show how blending rates and aperture sizes affect the LFs. The smallest possible apertures should be used in crowded regions.