Carnegie Supernova Project-II: Using Near-infrared Spectroscopy to Determine the Location of the Outer 56Ni in Type Ia Supernovae
Abstract
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.
This Letter includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.- Publication:
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The Astrophysical Journal
- Pub Date:
- April 2019
- DOI:
- 10.3847/2041-8213/ab1654
- arXiv:
- arXiv:1902.10088
- Bibcode:
- 2019ApJ...875L..14A
- Keywords:
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- supernovae: general;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in ApjL