Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark e-mail: firstname.lastname@example.org
2 Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile
3 The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
4 Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101, USA
5 Department of Physics, Texas A&M University, College Station, TX 77843, USA
6 Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
7 Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA
8 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
9 Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, PO 2611, Australia
10 Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark
11 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching bei München, Germany
Accepted: 7 July 2009
Aims. We study a thermonuclear supernova (SN), emphasizing very late phases.
Methods. An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. This includes 82 epochs of optical imaging, 24 epochs of near-infrared (NIR) imaging, and 10 epochs of optical spectroscopy. These data are combined with published nebular-phase IR spectra, and the observations are compared to model light curves and synthetic nebular spectra.
Results. SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B-band decline-rate parameter, = 1.61 ± 0.02. The blueshift of the most isolated [Fe ii] lines in the nebular-phase optical spectrum appears consistent with those observed in the IR at similar epochs. At late times there is a prevalent color evolution from the optical toward the NIR bands. We present the latest-ever detection of a SN Ia in the NIR in Hubble Space Telescope images. The study of the ultraviolet/optical/infrared (UVOIR) light curve reveals that a substantial fraction of the flux is “missing” at late times. Between 300 and 700 days past maximum brightness, the UVOIR light curve declines linearly following the decay of radioactive 56Co, assuming full and instantaneous positron trapping. At 700 days we detect a possible slowdown of the decline in optical-bands, mainly in the V-band.
Conclusions. The data are incompatible with a dramatic infrared catastrophe (IRC). However, the idea that an IRC occurred in the densest regions before 350 days can explain the missing flux from the UVOIR wavelengths and the flat-topped profiles in the NIR. We argue that such a scenario is possible if the ejecta are clumpy. The observations suggest that positrons are most likely trapped in the ejecta.
Key words: supernovae: general / supernovae: individual: SN 2003hv
Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Programmes 073.D-0294(AB), 074.D-0259(BC) and 075.D-0116(AB)), Cerro Tololo Inter-American Observatory, Lick Observatory, Las Campanas Observatory, Siding Spring Observatory, and the Hubble Space Telescope.
© ESO, 2009