1. SN Ia rates and progenitors Mark Sullivan University of Southampton

2. Supernova Legacy Survey 3-year sample Nearly 500 SNe Ia Sullivan et al. 2011 The cosmological power of SNe Ia Minus SNe: SNe Ia are still essential for a meaningful measurement of dark energy Conley et al. 2011 With SNe:

3. High-z searches (SNLS, SDSS, ESSENCE) New low-z searches (PTF, PS-1) SCP and HZSST LOSS Calan/Tolo lo survey

4. Astrophysics of SNe Ia White-dwarf/white-dwarf “merger” (double degenerate; DD) Accretion from a non-degenerate companion (single degenerate; SD) Accretes from a wind (symbiotic channel)? Roche Lobe over-flow? Roche Lobe over-flow? Helium star channel? How does the SN Ia progenitor influence the explosion? What are the progenitors of SNe Ia and what can we learn from observations?

5. Cosmological application SNe are standardizable, not standard, candles Brighter SNe: Have wider, slower light curves (classic Phillips relation), Have wider, slower light curves (classic Phillips relation), Are bluer in their optical colour, Are bluer in their optical colour, Have a dependence on their host stellar populations. Have a dependence on their host stellar populations. Relative brightness

6. How does this progenitor diversity map into the cosmology? Kelly et al., Sullivan et al., Lampeitl et al., 2010

7. Palomar Transient Factory (PTF) Wide-angle, variable cadence sky survey Looking for supernovae, novae, CVs 2 day cadence, search in g or R SN-like transient every 20 minutes on sky PESSTO has 25% of the NTT for 4 years 2000 classifications; 150 SNe detailed studies All data public! PESSTO

8. SN 2011fe Transient located by PTF on night of August 23 rd (Palomar) Found in M101 – ~6Mpc Went from non-detection to 17 th magnitude in 24 hours. Early time data rule out a red giant companion (at time of explosion) Nugent et al. 2011

9. Direct progenitor imaging No progenitor (companion) star detected in HST imaging 10-100 times fainter limits than previous Ia progenitor studies Other complementary studies also place severe limits on SD scenarios Li et al. 2011

10. PTF11kx SN Ia, z=0.047, slightly over-luminous Remarkable optical spectra; Ca H,K absorption Prompted detailed high-resolution study that revealed two CSM “shells” Dilday et al. 2012

11. Hydrogen points to a SD progenitor Ca II switches to emission in the later spectra – ejecta running into circumstellar material (CSM) Also time variable Fe, Ti, Na, He lines High resolution studies indicate at least two distinct shells of CSM Shells of material: Ca, H, Fe, Na, etc. Dilday et al. 2012

12. Model must explain: – – Multiple components of CSM, – – A region evacuated of CSM, leading to a delay between explosion and the emergence of broad Ca and H. A SN Ia in a symbiotic nova system mayexplain these features: accretion onto a WD through the wind from a red giant star. However the CSM mass is very high PTF11kx progenitor system Dilday et al. 2012 See also core-degenerate scenario (Soker et al. 2013) Prompt merger of WD and AGB star core

13. Broad hydrogen emission strengthens with time, until a sudden drop Possibly indicates SN ejecta has overtaken most of the CSM Silverman et al. 2013a

14. Further “Ia-CSM” Careful search of PTF and literature SNe IIn Now ~16 known members of the class with strong CSM All located in star-forming galaxies Silverman et al. 2013b

15. “Weaker” CSM High-resolution spectra of some SNe Ia show time variable blue- shifted CSM (eg SN 2006X; Patat et al 2007) Majority of SNe Ia in spirals show blue-shifted Na I D lines, outflow from system No CSM observed in SNe Ia in elliptical galaxies Sternberg+ (2011) SN 2006X, Patat+ (2007) Rs Oph, Patat+ (2011)

16. VLT+XShooter CSM programme ToO programs on VLT+XShooter Measure Na I D absorption Maguire, Sullivan et al. 2013

17. Results: Host galaxy properties Na I D features more common in star forming galaxies Less CSM in elliptical galaxies Younger population Maguire, Sullivan et al. 2013

18. Results: Link to progenitors SNe Ia displaying blueshifted CSM have on average higher stretches Maguire, Sullivan et al. 2013

19. But stretch also depends on galaxy type Low SFR High SFR

20. Results: Link to progenitors SNe Ia displaying blueshifted CSM have on average higher stretches Maguire, Sullivan et al. 2013

21. Link to luminosity? Spectral luminosity indicator - pEW of Si II 4130A line SNe Ia displaying blue-shifted material have weaker Si II Maguire, Sullivan et al. 2013

22. Delay-time distribution DTD – time from SN progenitor formation to explosion Strong evidence for both young and old components Power-law t -1 fits the data well

23. DTD and the volumetric rate Perrett, Sullivan et al. 2012 Power-law is a good fit to the data

24. But problems with the normalisation…. Perrett, Sullivan et al. 2012 Fraction of 3-8M  stars exploding as SNe Ia: η=2-2.5% (From SNLS data)

25. DTD from SNLS galaxy data Pritchet et al. in prep

26. t -1.35 Power-law fit Pritchet et al. in prep

27. Stretch dependence of DTD Hints of something interesting with stretch… Pritchet et al. in prep

28. Two families of ‘normal’ SNe Ia?

29. Photometric properties

30. Two families of ‘normal’ SNe Ia? Photometric properties Spectral properties

31. Two families of ‘normal’ SNe Ia? Photometric properties Spectral properties Host properties

32. Two families of ‘normal’ SNe Ia? Photometric properties Spectral properties Host properties Delay-time Distribution

33. Two families of ‘normal’ SNe Ia? Photometric properties Spectral properties Host properties Different progenitor types? Delay-time Distribution Environment