Photometric study of the late-time near-infrared plateau in Type Ia supernovae

We present an in-depth study of the late-time near-infrared plateau in Type Ia supernovae (SNe Ia), which occurs between 70-500 d. double existing sample SNe observed during with new observations taken Hubble Space Telescope, Gemini, New Technology 3.5m Calar Alto and Nordic Optical Telescope. Our consists 24 nearby at redshift < 0.025. are able to confirm that no exists Ks band for most normal Ia. broader optical light curves peak tend have a higher average brightness on J H, likely due shallower decline preceding 100 more luminous also show steeper phase H. compare our data state-of-the-art radiative transfer models nebular near-infrared. find good agreement sub-Mch model has reduced non-thermal ionisation rates, but physical justification reducing these rates yet been proposed. An analysis spectral evolution demonstrates ratio [Fe II] III] contribution filter determines curve said filter. overluminous slower than expected from trend seen