Spectroscopic Sequence Among SNe Ia

1. Spectroscopic Sequence Among SNe Ia Peter Nugent(LBNL/UCB)

2. SNe Ia circa 1993 Phillips (1993 - 9 SNe Ia) and Branch, Fisher & Nugent (1993 - 84 SNe Ia ) were what we had readily available to analyze photometrically and spectroscopically at the time.

3. Spectroscopic Sequence Nugent et al (1995) – just a temperature sequence... Presumably related to the 56Ni production.

4. R(SiII) & R(CaII) Why did we like such an idea? “Simple theories for simple minds...” (E. Quataert) In 1995, we thought we knew almost everything about SNe Ia. Unlike the Sun, which is “so hard to understand due to all the data...” (C. Wheeler)

5. Chandrasekhar Mass Arnett (1982) – told us that the opacity could drive the lightcurve shape – though he had it wrong.

6. Sub-Chandra’s? – No. Nugent et al (1997) Models of Woosley & Weaver (1994) and Livne & Arnett (1995) do not match observations spectroscopically. Photometrically they were impressive. However, ~0.2 M of He blowing up pollutes the spectrum at high velocities.

7. More data Calán-Tololo search confirmed these relationships. But I never bothered to publish this....

8. New searches (500/yr) SNf, SDSS, PTF... High-Z Searches KAIT Calán-Tololo Search Zwicky + Amateurs Complacency Why was our “understanding” of SNe Ia so readily accepted? Cosmology. While we had no idea where SNe Ia came from, we wanted to believe we understood them. There were proposals to write...

9. And more data... Branch, Dang & Baron (2009). This is a much better way to look at the data.

10. Controlled Search Silverman et al (2012) shows that things are starting to break down. Of note the blue symbols are “high-velocity” SNe Ia.

11. Palomar Transient Factory P60: Followup P48: Discovery Engine

12. PTF Science The power of PTF resides in its diverse science goals and follow-up.

13. PTF Science Liverpool Telescope The power of PTF resides in its diverse science goals and follow-up.

14. Orphan Afterglow z=1.98!!! FeII, MgII, Ly-α iPTF14yb Cenko et al. 2014 IPN found a GRB (localization ~200-300 sq. deg.) ~15 min before first detection.....

15. Stats 1500+ SNe Ia PTF/iPTF: 2200+ Spectroscopically Classified Transients 80+ Refereed Papers (all but a handful on single SNe)

16. R(SiII) from PTF Joe DeRose & Nao Suzuki put together ~200 SNe Ia which we took spectra of near max and had a good measurement of the lightcurve shape. Majority are good, though things are breaking down...

17. Sub-Chandra’s Revived Scalzo’s work on modeling the ejecta mass, coupled with the UCSB group’s work on shrinking the He layer to ~< 0.05 M Now there is very little 56Ni in the outer layers.

18. Sub-Chandra’s Revived Woosley & Kasen (2011) Outer shell explosions on the left, full star explosed on the right. Nice relationship between MWD and 56Ni production which, together, drives the lightcurve shape - luminosity relationship. Spectroscopic sequence has the right ingredients and can be maintained.

19. Sub-Chandra’s Revived Sim et al (2010) And is maintained... R(Si II) works for sub-Chandra’s.

20. What else is off? Super-Chandra’s Vphot ~ 8000 km/s at 2 days before peak brightness Also observed are CII lines – Howell et al (2006) Mbol = -19.9 S = 1.13

21. SNF20070825-001 Nothing on Aug 9, mag 17.7 on Aug. 25th, spectrum that night.

22. SNF20070825-001 ROTSE’s early light-curve + Palomar 200” spectroscopy convinced us that this was something to look at again…

23. SNF20070825-001 And now we know what it is… a SNLS-03d3bb look-alike. With R~17.4, and z~0.07, this SN has MV=-20 Scalzo et al (2010)

24. What Next…another one SNF20080723-012 z=0.075

25. What Next…another one SNF20080723-012 z=0.075

26. Rates... TBD: (Frohmaieret al, in prep) However, we have ~20 of these in PTF/iPTF out of 1200 SNe Ia. Rare (1%-ish) and associated with heavy star formation. However, likely to be confused with CC SNe at high-z due to their UV-brightness.

27. Ia-CSM 11kx directly relates the 2002ic and 2005gj SNe to Ia’s and measures a size for the CSM. Dilday et al (2012)

28. Ia-CSM RS Oph – like? 11kx directly relates the 2002ic and 2005gj SNe to Ia’s and measures a size for the CSM.

29. Ia-CSM Silverman et al (2013) identifies a group of them in the LOSS and PTF datasets. H-alpha to H-beta ratio is large, weak He I lines, slightly brighter than a SN Ia. Rates are low (1%-ish), but it might be biased by how we have identified them. What if the CSM was 3 times farther away.... See Harris’ talk. Late-time observations!!!

30. 2006bt-10ops Far-flung (30 - 130 kpc) Maguire et al (2011): 10ops – these are broad, but cool. Si(II) Ratio is very wrong!

31. 2006bt-10ops Far-flung (30 - 130 kpc) Maguire et al (2011): 10ops – these are broad, but cool. Si(II) Ratio is very wrong!

32. Exceptional - PTF10zej No large host nearby. Spectroscopically like 1986G/10ops. Why did we “find” this one – no host. We have 4 in PTF...so far.

33. Rates of these??? Need to look carefully at these, especially wrt cosmology. One thing working for us is that they are quite old, we hope...

34. Conclusions Observers: • Late-time observations, especially for 99aa-91T • Publish spectra with lightcurves en masse • Start doing rates • Be like PTF/KAIT – complete • Go beyond simple host correlations - crude • Go early as possible – signatures for sub-chandra? Theorists: • Smash SNe into CSM H/He & C/O – do spectra and lightcurves • Push on the sub-chandra models until they break, we may see other interesting objects (09dav, 10ops, etc.) • Do theoretical rates better for these • Don’t be pressured by observations Merge theory and observation: See the Goldstein,Thomas & Kasen poster upstairs.