Type Ia Supernovae with Bi-Modal Explosions Are Common -- Possible Smoking Gun for Direct Collisions of White-Dwarfs
| Autor: | Dong, Subo, Katz, Boaz, Kushnir, Doron, Prieto, Jose L. |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | MNRAS (November 21, 2015) 454 (1): L61-L65 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnrasl/slv129 |
| Popis: | We discover clear doubly-peaked line profiles in 3 out of ~20 type Ia supernovae (SNe Ia) with high-quality nebular-phase spectra. The profiles are consistently present in three well-separated Co/Fe emission features. The two peaks are respectively blue-shifted and red-shifted relative to the host galaxies and are separated by ~5000 km/s. The doubly-peaked profiles directly reflect a bi-modal velocity distribution of the radioactive Ni56 in the ejecta that powers the emission of these SNe. Due to their random orientations, only a fraction of SNe with intrinsically bi-modal velocity distributions will appear as doubly-peaked spectra. Therefore SNe with intrinsic bi-modality are likely common, especially among the SNe in the low-luminosity part on the Philips relation (\Delta m15(B) >~ 1.3; ~40% of all SNe Ia). Such bi-modality is naturally expected from direct collisions of white dwarfs (WDs) due to the detonation of both WDs and is demonstrated in a 3D 0.64 M_Sun-0.64 M_Sun WD collision simulation. In the future, with a large sample of nebular spectra and a comprehensive set of numerical simulations, the collision model can be unambiguously tested as the primary channel for type Ia SNe, and the distribution of nebular line profiles will either be a smoking gun or rule it out. Comment: To be published by MNRAS Letters. Minor changes of the main text, an Appendix added |
| Databáze: | arXiv |
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