# Presentation: 155001

## SNLS & Type II-P Supernovae

- A Hubble Diagram for Today
- and the Future
- Peter Nugent (LBNL)

## Type II’s

- A Type II means we see hydrogen in the spectrum.
- II-P = Plateau-like lightcurve in the optical.
-  II-L = Linearly declining lightcurve in the optical.
- II-n = Narrow Balmer lines seen in optical spectrum.

- SNLS Collaboration Meeting

## Type II-P’s

- A Type II-P is most likely a 8-15 Msolar star that undergoes core-collapse.
- Unlike the II-n’s and II-L’s it is probably not in a binary systemand is not experiencing an interaction with the circumstellar material around it.

- SNLS Collaboration Meeting

## What about Type II’s

- At low z (< 0.1) they are 5 times more abundant than Ia’s.
- They directly follow the SFR, thus increasing by several fold at high-z.
- But they are much fainter...

- SNLS Collaboration Meeting

## What about Type II’s

- Based on this we expect about 8
- SNe-IIP per SNLS pointing over the entire observing period brighter than 24th magnitude.

- SNLS Collaboration Meeting

## EPM

- Measuring Distances to Type II’s - Think:
- EPM, the Expanding Photosphere Method (Baade –Wesselink Method)
- Type II Supernovae (made mostly of Hydrogen) are like hot,
- diffuse blackbodies that expand homologously.

- Velocity is measured from spectra, time is from the explosion date.
- Zeta is the dilution factor - calculated from models.

- SNLS Collaboration Meeting

## Type II models

- Distances to Type II's:
- Spectral Expanding Atmosphere Method
- or SEAM
- The physics is dominated by hydrogen, thus in principle they are much easier to understand than Ia’s.

- SNLS Collaboration Meeting

## Hamuy’s Method

- Mario Hamuy’s Technique:
- Basically velocity
- is proportional to brightness at t = 50 days
- Why should this work?

- SNLS Collaboration Meeting

## Measurements

- Lightcurves from SNLS.
- Spectra from Keck.
- Measure the velocity from weak FeII lines that best represent where the photosphere is located.
- Problems:
-  Fainter
-  Buried in host
-  Lines are weak
-  Aspherical

- SNLS Collaboration Meeting

## Improving Hamuy’s Method

- Two major fixes:
-  Color Corrections
-  Velocity measurements

- Old HP02 term

- New term relating observed 50 day color to extinction

- SNLS Collaboration Meeting

## Improving Hamuy’s Method

- Fe II (5169) isn’t always the easiest line to measure.

- Therefore we came up with correlations to use H-beta and FeII (5018). Cross-correlation measurements.

- SNLS Collaboration Meeting

## SNLS Type-IIP

**SNLS Type-IIP**

- SNLS Collaboration Meeting

## SNLS Type-IIP

- The lightcurves are so nice that we often catch the shock breakout. We clearly have a lot of information that we are not exploiting...

- SNLS Collaboration Meeting

## Keck Obs. of Type-IIP

- These are incredibly demanding observations, ~2hr for this spectrum, to get enough S/N in the weak FeII lines.

- SNLS Collaboration Meeting

## Velocity Correlations

- Doug Leonard has shown that the FeII(5169)  velocities decline monotonically as a function of time. They actually have an e-folding time of 89days which we can exploit since not all our observations are at day 50 and we need to extrapolate.

- SNLS Collaboration Meeting

## Hubble Diagram

- With all uncertainties factored in:
-  Extinction
-  Explosion date
-  Photometry
-  Velocity
- Large MC to handle all the correlations.

- SNLS Collaboration Meeting

## Conclusions

-  A very good high-z program for SNII-P underway.
-  We do need to improve the low-z component, this is underway at Caltech/Palomar.
-  Dispersion is 0.24 mag, this will certainly improve as we get better low-z data and figure out how to take advantage of the quality of the high-redshift data. And...

- SNLS Collaboration Meeting

## Future

- TMT - JWST - JDEM - LSST.....

- SNLS Collaboration Meeting