Carnegie Supernova Project: Observations of Type IIn supernovae^{⋆,⋆⋆,⋆⋆⋆}

¹ The Oskar Klein Centre, Department of AstronomyStockholm University, AlbaNova, 10691 Stockholm, Sweden
e-mail: francesco.taddia@astro.su.se
² Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
³ Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena, Chile
⁴ Departamento de Astronomia, Universidad de Chile, Casilla 36D, Santiago, Chile
⁵ Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53111 Bonn, Germany
⁶ Kavli Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583 Chiba, Japan
⁷ Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA, USA
⁸ N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa, Poland
⁹ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77845, USA
¹⁰ The Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77845, USA

Received: 29 January 2013
Accepted: 10 April 2013

Abstract

Aims. 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.

Methods. 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, the full CSP sample is used to derive physical parameters that describe the nature of the interaction between the expanding SN ejecta and the circumstellar material (CSM).

Results. 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, mass-loss rates of 10^-4−10^-2M_⊙ yr^-1 are derived, assuming the CSM was formed by steady winds. Typically wind velocities of a few hundred km s^-1 are also computed.

Conclusions. The CSP SN IIn sample seems to be divided into subcategories rather than to have exhibited a continuum of observational properties. The wind and mass-loss parameters would favor 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 cannot be excluded at this time.