Carnegie Supernova Project-II: Using Near-infrared Spectroscopy to Determine the Location of the Outer Ni-56 in Type Ia Supernovae Academic Article uri icon


  • 2019. The American Astronomical Society. All rights reserved. We present the H-band wavelength region of 37 postmaximum light near-infrared spectra of three normal, nine transitional, and four subluminous type Ia supernovae (SNe Ia), extending from +5 days to +20 days relative to the epoch of B-band maximum. We introduce a new observable, the blue-edge velocity, v edge, of the prominent Fe/Co/Ni-peak H-band emission feature, which is quantitatively measured. The v edge parameter is found to decrease over subtype ranging from around -14,000 km s-1 for normal SNe Ia, to -10,000 km s-1 for transitional SNe Ia, down to -5000 km s-1 for the subluminous SNe Ia. Furthermore, inspection of the +10 3 days spectra indicates that v edge is correlated with the color-stretch parameter, s BV, and hence with peak luminosity. These results follow the previous findings that brighter SNe Ia tend to have 56Ni located at higher velocities as compared to subluminous objects. As v edge is a model-independent parameter, we propose it can be used in combination with traditional observational diagnostics to provide a new avenue to robustly distinguish between leading SNe Ia explosion models.

published proceedings


altmetric score

  • 8

author list (cited authors)

  • Ashall, C., Hsiao, E. Y., Hoeflich, P., Stritzinger, M., Phillips, M. M., Morrell, N., ... Taddia, F.

citation count

  • 20

complete list of authors

  • Ashall, C||Hsiao, EY||Hoeflich, P||Stritzinger, M||Phillips, MM||Morrell, N||Davis, S||Baron, E||Piro, AL||Burns, C||Contreras, C||Galbany, L||Holmbo, S||Kirshner, RP||Krisciunas, K||Marion, GH||Sand, DJ||Shahbandeh, M||Suntzeff, NB||Taddia, F

publication date

  • April 2019