1. SN Ia diversity as an indicator of multiple progenitors? Andy Howell University of California, Santa Barbara Las Cumbres Observatory Global Telescope Image: UC Santa Barbara

2. The Astonomer by Candlelight Gerrit Dou (~1665-1660) Getty Museum, Los Angeles, CA Dou was Rembrandt's first student and later the leader of the "fijnschilders" (fine painters), a group of painters in Leiden. Fijnschilders were known for their meticulous attention to detail in striving to reproduce reality as closely as possible. They are also known for everyday subjects, nocturnal scenes, and “trompe l’oeil” (niche) paintings. Quote from the Getty: “The prominent candle and hourglass are traditional symbols of the brevity of life, suggesting that the astronomer symbolizes the vanity of the human desire to comprehend the infinite”

3. Zoals de ouden zongen piepen de jongen As the old sang, so do the young shriek Jan Steen (Leiden) About the old corrupting the young Cubist version! So there is a progenitor!

4. Outline: SN Ia diversity as an indicator of multiple progenitors What counts as a SN Ia? Rates / Delay Time Distributions Environment Spectra CSM Reddening Pros / Cons of models

5. SN 2007if +5d; Scalzo et al. 2010 Foley et al. 2010 What counts as a SN Ia?

6. M Ni M ej refNormal ~0.2-0.91-1.4 Stritzinge r SN 2007if 1.62.4Scalzo 08ha ~0.001?~0.2?Foley Data: McClelland et al. 2010, Scalzo et al. 2010 Factor of 600 Factor of 20 What counts as a SN Ia?

7. Sullivan et al. 2010 (SNLS) Environmen t

8. Sullivan et al. 2010 (SNLS) Environmen t

9. Maoz et al. 2010 (LOSS) Brandt et al. 2010 (SDSS) Probably not two clearly distinct channels. A continuum? But stretch, luminosity depend on age! Can one model explain all? Rates / Delay Time Distributions

10. Branch et al. 2009: SiII phenomenology. Combines abundance, temperature, velocity effects Spectr a

11. X. Wang et al. 2009 Benetti et al. 2006 Spectra: Velocities

12. X. Wang et al. 2009 Reddening

13. Maeda et al. 2010 Spectr a

14. Maeda et al. 2010 Spectr a

15. Reddening Folatelli et al. 2010 (CSP)

16. CSM: Variable Sodium Simon et al. 2009 SN 2007le: Na I D strengthens over time. Consistent with dense (10 7 cm -3 ) cloud ~0.1 pc from SN. E B-V =0.27 Blondin et al. 2009 Out of 31 low-res spectra where variable Na I D at the level in SN 2006X could have been detected, only 2 (6%), SN 2006X and SN 1999cl, showed variable Na I D. These were the most highly reddened objects in the sample: E B-V(host) >1 mag Patat et al. 2007 SN 2006X: Na I D strengthens over time (but not Ca II H&K). Consistent with CSM ionization, then recombination.

17. Hamuy et al. 2003, Aldering et al. 2006 SN Ia in CSM. Recent mass loss. Secondary is AGB star? Some say not a Ia: Benetti et al. 2006 But Hydrogen not seen even at late times in two SNe with good limits: Leonard et al. 2007 CSM: SNe IIn-Ia, SN 2002ic and SN 2005gj

18. X. Wang et al. 2009

20. Maeda et al. 2010

21. Conclusions What counts as a SN Ia? -We aren’t sure. Large Diversity. Rates / Delay Time Distributions - Probably not a bimodal distribution - But stretch/luminosity depends on delay time - SD model has a hard time explaining all SNe Environment - Galaxy size plays a role, possibly implicating metallicity - Age of progenitor probably matters - SNe correct to different abolute magnitudes in different environments - Reddening or color depends on host galaxy Spectra - SNe Ia can be grouped based on spectra features - This is especially true of velocity. - Geometric effects may unify some of the diversity CSM - Some SNe show signs of CSM, but they are the minority - Different progenitors or geometric effects? Reddening - Reddening depends on host - Reddening probably depends on dust amount / density - Some may be intrinsic SN color/luminosity relaion - Some may be circumstellar.

22. Howell et al. 2010