* Astronomy

Title: Carnegie Supernova Project: Observations of Type IIn Supernovae
Authors: F. Taddia, M. D. Stritzinger, J. Sollerman, M. M. Phillips, J. P. Anderson, L. Boldt, A. Campillay, S. Castellón, C. Contreras, G. Folatelli, M. Hamuy, E. Heinrich-Josties, W. Krzeminski, N. Morrell, C. R. Burns, W. L. Freedman, B. F. Madore, S. E. Persson, N. B. Suntzeff

The observational diversity displayed by various Type IIn supernovae (SNe IIn) is explored and quantified. In doing so a more coherent picture ascribing the variety of observed SNe IIn types to particular progenitor scenarios is sought. Carnegie Supernova Project (CSP) optical and near-infrared light curves and visual-wavelength spectroscopy of the Type IIn SNe 2005kj, 2006aa, 2006bo, 2006qq and 2008fq are presented. Combined with previously published observations of the Type IIn SNe 2005ip and 2006jd (Stritzinger et al. 2012), the full CSP sample is used to derive physical parameters which describe the nature of the interaction between the expanding SN ejecta and the circum-stellar material (CSM). For each SN of our sample we find counterparts, identifying objects similar to SNe 1994W (SN 2006bo), 1998S (SN 2008fq) and 1988Z (SN 2006qq). We present the unprecedented initial u-band plateau of SN 2006aa, and its peculiar late-time luminosity and temperature evolution. For each SN, assuming the CSM was formed by steady winds, mass-loss rates of 10^{-4}-10^{-2} solar masses yr^{-1} are derived. Typically wind velocities of a few hundreds km s^{-1} are also computed. The CSP SN IIn sample seems to be divided into sub-categories rather than exhibiting a continuum of observational properties. The wind and mass-loss parameters would favour a Luminous Blue Variable progenitor scenario, however the assumptions made to derive those parameters strongly influence the results, and therefore other progenitor channels behind SNe IIn can not be excluded at this time.

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