1. Spectroscopic signatures of SN Ia progenitors A talk not about the Palomar Transient Factory Avishay Gal-Yam, Weizmann Institute of Science Leiden workshop 2010

2. Preamble Lots of time for questions What is a type Ia SN? Not going to cover: CSM interaction, CSM absorption

3. The basics: data+models Sauer et al. 2008 Chandrasekhar-mass C/O models fit the data well

4. Progenitor signatures: 1 Hydrogen and helium: no convincing evidence

5. Progenitor signatures: 2 Carbon: evidence for C/O progenitor (not O/Ne) Indicative of deflagration Strong in super-C events (Howell) Mazzali 2001 Tanaka et al. 2010 Howell et al. 2006

6. Progenitor signatures: 3 Ca high-velocity features – CSM (SD)? Or else, 3D effects? Tanaka et al. 2008

7. Faint events (1991bg-like) High velocity oxygen shell No outer He shell Mazzali et al. 1997

8. Interim summary SNe Ia are explosions of C/O WDs with mass ~M Ch How much C survives ? There are no traces of H or He (no outer He shell) H CSM may be indicated (SD) What are SNe Ia? What can we learn from other SNe?

9. Shy cousins: SN 2005E LOSS discovery Graham & Li 2005 Type Ib (UCB; CCCP) Member of the Ca-rich Subclass (Filippenko et al.) Hagai Perets, Nature, in press Dave Arnett, Paolo Mazzali, Daniel Kagan, UCB SN group, CCCP, Anderson & James, Ofek, Bildsten & Co., Quataert & Co.

10. A massive star? No star formation to deep limits … unlikely also on theoretical grounds Perets et al. 2009 r<25.3 (25.9) at 3(2) 

11. A hyper-velocity SN (HVSN) ? Life in the fast lane? SN 2005E 11.3 kpc 22.9 kpc Not likely: chances to observe HVSNe with LOSS are < 1/100

12. So what, then? What will nebular spectra reveal? Peculiar abundances (C, O, Ca, Ni56) = (0.1 0.037 0.135 0.003) solar Total ejected mass is <0.3 solar ! Mazzali

13. Not a single event! 6-10 additional siblings, additional early hosts

14. What can it be? A double WD (O/Ne+He): accretion induced collapse ? Or else, CO/He DD merger (Waldman models)

15. Nucleosynthesis Can you make so much Ca with no Si and S? (Ca/S >6) * No (if you burn C/O) * Yes (if you burn He) Models by Arnett } Confirmed by details models by Waldman et al.

16. Can we start mapping? Normal SNe Ia: SD? SN 2005E CO/He DD? Faint SNe Ia: CO/CO DD?

17. Thanks