The normal Type Ia SN 2003hv out to very late phases

\n Aims. We study a thermonuclear supernova (SN), emphasizing\nvery late phases.\n Methods. An extensive dataset for SN 2003hv that\ncovers the flux evolution from maximum light to day +786 is\npresented. This includes 82 epochs of optical imaging, 24 epochs\nof near-infrared (NIR) imaging, and 10 epochs of optical\nspectroscopy. These data are combined with published\nnebular-phase IR spectra, and the observations are compared to\nmodel light curves and synthetic nebular spectra.\n Results. SN 2003hv\nis a normal Type Ia supernova (SN Ia) with photometric and\nspectroscopic properties consistent with its rarely observed\nB-band decline-rate parameter, $\\Delta m_{15}(B)$ = 1.61 ±\n0.02. The blueshift of the most isolated [Fe <sc>ii</sc>] lines in\nthe nebular-phase optical spectrum appears consistent with those\nobserved in the IR at similar epochs. At late times there\nis a prevalent color evolution from the optical toward the NIR\nbands. We present the latest-ever detection of a SN Ia in the NIR\nin Hubble Space Telescope images. The study of the\nultraviolet/optical/infrared (UVOIR) light curve reveals that a\nsubstantial fraction of the flux is “missing” at late times.\nBetween 300 and 700 days past maximum brightness, the UVOIR light\ncurve declines linearly following the decay of radioactive 56Co,\nassuming full and instantaneous positron trapping. At 700 days we\ndetect a possible slowdown of the decline in optical-bands, mainly\nin the V-band.\n Conclusions. The data are incompatible with a dramatic\ninfrared catastrophe (IRC). However, the idea that an IRC occurred\nin the densest regions before 350 days can explain the missing\nflux from the UVOIR wavelengths and the flat-topped profiles in\nthe NIR. We argue that such a scenario is possible if the ejecta\nare clumpy. The observations suggest that positrons are most\nlikely trapped in the ejecta.\n