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arXiv · 1302.0768

The K-band luminosity functions of super star clusters in luminous infrared galaxies, their slopes, and the effects of blending

Zara Randriamanakoto·Petri Vaisanen·Stuart Ryder·Erkki Kankare·Jari Kotilainen·Seppo Mattila
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Abstract

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 (VLT/NACO and Gemini/ALTAIR/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 the values of the index αranging between 1.5 to 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 $D_L$ ~ 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 Antennae system which is artificially redshifted to distances of our sample. While blending tends to flatten LFs our analyses show that Δαis less than ~ 0.1 in our sample. The simulations also show that in the luminosity range, $M_K < -13$, considered in this work the extracted SSC luminosities are generally dominated by a single dominant star cluster rather than several knots of SF. 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.

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Zara Randriamanakoto, Petri Vaisanen, Stuart Ryder, Erkki Kankare, Jari Kotilainen, Seppo Mattila. 2013-02-04. The K-band luminosity functions of super star clusters in luminous infrared galaxies, their slopes, and the effects of blending. https://doi.org/10.1093/mnras%2Fstt185

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