We present near-infrared observations of the nuclei of 22 LINER and starburst galaxies. Most of the galaxies that make up our sample exhibit a smooth regular near-infrared structure. A few show more complex morphologies with ‘hotspots’. Colour index maps indicate the combined effects of dust obscuration, emission from hot dust, and stellar population gradients. We describe a method, based on a generalized Gaussian fit to the galaxy profile, which estimates the flux due to a point source within the galaxy. This method provides an alternative to traditional procedures for estimating the nuclear component, irrespective of whether this is due to a compact cluster of stars or an obscured Seyfert nucleus. The nuclear near-infrared emission correlates with the soft X-rays and 6-cm radio emission. This is consistent with both star formation or a mini black hole as the source of the nuclear activity. Most of these galaxies have extended near-infrared emission. This strongly supports a starlight and/or thermal dust origin for the emission. We predict that in many cases the X-ray emission will also be extended. From this study there is no strong evidence at near-infrared wavelengths to support the idea that LINER and starburst galaxies harbour black holes at their centres.
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Forbes et al. (1992) studied this question.