# Presentation: 382629

## ∆m15(B) Method

**∆****m****15****(B) Method**

-  *BVI* light curves are fit to templates of 7 SNe (92bc, 91T, 92al, 92A, 92bo/93H, 91bg) selected to cover the observed range of ∆m15(B)
-  Maximum magnitudes are given by template fit with lowest 2
-  ∆m15(B) is estimated by fitting a parabola to plot of template ∆m15(B) vs. 2

**See: Hamuy et al. (1996); Phillips et al. (1999)**

## The B-V Color Evolution of Unreddened SNe Ia

**From: Phillips et al. 1999**

- “Lira Law”

## The B-V Color Evolution of Unreddened SNe Ia

**The B-V Color Evolution of Unreddened SNe Ia**

## Colors at Maximum Light for Unreddened SNe Ia

**Colors at Maximum Light ****for Unreddened SNe Ia**

**Scatter corresponds to ****± 0.05 mag in E(B-V)**
***This is as well as we can currently determine the reddening of an individual SN Ia***

## The Luminosity vs Decline Rate Relation for SNe Ia

**The Luminosity vs Decline Rate Relation for SNe Ia**

**All SNe**

**Unreddened SNe**

**From: Phillips et al. 1999**

## Luminosity vs. Color Relations

**Luminosity vs. Color Relations**

## Host Galaxy Dust Reddening:

**  ****“****Lira law” makes it possible to estimate intrinsic B****max****-V****max**** and V****max****-I****max**** vs. ∆m****15****(B) relations**
**  ****The B****max****-V****max**** vs. ∆m****15****(B) relation is nearly flat**
**  ****The luminosity vs. decline rate relations for “unreddened” events define tight sequences**
**  ****On average, the host galaxy dust is characterized by R****B**** ~ 3.2, R****V**** ~ 2.4, and R****I**** ~ 1.6      ****Why?  Why do others find R****B**** ~ 2??  Samples??  Lira law???**

## A Recent Improvement on the ∆m15(B) Method from Prieto et al.

**A Recent Improvement on the ∆m****15****(B) Method from Prieto et al.**

**Start with 14 well observed SN Ia as templates...**

**From: Prieto et al. 2006**

## ...and use a triangle weighting function (width ~0.20-0.35 mag) to generate a continuous set of templates parameterized by ∆m15(B)

**...****and use a triangle weighting function (width ~0.20-0.35 mag) to generate a continuous set of templates parameterized by ∆m****15****(B)**

**From: Prieto et al. 2004**

## Sample fits (good & bad)

**Sample fits (good & bad)**

**From: Prieto et al. 2004**

## CSP i’ light curves

- i’ templates

## UBVRIJHK Light Curves of a Typical SN Ia

**Sources:**
**UBVRI: Suntzeff et al. (1999)**
**JHK:****	****Mayya et al. (1998)**
**	****Jha et al. (1999) ****	****	****	****Hernandez et al. (2000)**

**UBVRIJHK Light Curves of a Typical SN Ia**

**Secondary maximum**

**Primary maximum**

##   Secondary maximum occurs later for slower declining SNe

**SN  ********m****15****(*****B*****)**

***  *****Secondary maximum occurs *****later****** *****for *****slower***** ****declining SNe**
** ****Generally speaking, secondary maximum is *****stronger***** for ****slower**** declining SNe**

## Strength of Secondary Maximum vs. Decline Rate in the I Band

**Krisciunas et al. (2001)**

**Strength of Secondary Maximum vs. Decline Rate in the I Band**

## Ugh!

**Krisciunas et al. (2001)**

## Slide 16

## Slide 17

## Slide 18

## Morphology of JHK lightcurves of SNe Ia:

**  ****Primary maxima occur a few days**** *****before***** ****T(B****max****)**
**  ****As a general rule, the secondary maximum**** *****occurs later***** ****and is**** *****stronger***** ****in**** *****slower declining***** ****events**
**  ****Secondary maximum can be**** *****brighter***** ****than primary maximum (e.g., in Y & H bands)**
**  ****H & K light curves are relatively**** *****flat***** ****around T(B****max****)**

## JHK Light Curves of 6 well-observed SNe I

## JHK Light Curves of the same 6 SNe I, but corrected to a stretch equivalent to ∆m15(B) = 1.1

- JHK Light Curves of the same 6 SNe I, but corrected to a stretch equivalent to ∆m15(B) = 1.1

***Let’s zoom in on this time window, and do this more precisely (e.g., include K corrections)***

## Construction of JHK Stretch Templates

**Krisciunas et al. (2004)**

**Construction of JHK Stretch Templates**

****

**= 1980N (1.29)**
**= 1986G (1.79)**
**= 1998bu (1.05)**
**= 1999aw (0.81)**
**= 1999ee (0.94)**
**= 2000ca (1.01)**
**= 2001el (1.15)**

**SN  ********m****15****(*****B*****)**

## Fitting JHK Light Curves with the Stretch Templates

**Fitting JHK Light Curves with the Stretch Templates**

******m****15****(*****B*****) = 0.99**

******m****15****(*****B*****) = 1.73**

## Fitting JHK Light Curves with the Stretch Templates

**Fitting JHK Light Curves with the Stretch Templates**

******m****15****(*****B*****) = 1.28**

******m****15****(*****B*****) = 1.63**

## JHK light curve Templates for SNe Ia:

**  *****Stretch technique***** works well for JHK light curves in the window ****-12 to +10 days**** with respect to T(B****max****)**
**  ****Allows reasonable estimates to be made of the maximum light magnitudes in JHK ****without the need to actually obtain photometry at maximum light**

## Krisciunas et al. (2000)

**Krisciunas et al. (2000)**

**"Worst Case NIR"**
**Av = (1.126****±****0.072) x E(V-K)**

**"Best Case Optical"**
**Av = (3.1****±****0.1) x E(B-V)**

**"Realistic Case Optical"**
**Av = (2.6****±****0.3) x E(B-V)**

## Deriving the V-NIR Color Excess from the Observed Magnitudes at Maximum

- Eventually, this method should provide the most precise determinations of the host galaxy dust extinctions of SNe Ia

**From: Krisciunas et al (2004)**

## The Value of Optical + NIR Photometry for Deducing Host Galaxy Extinction 

**2004S vs. 2001el**

**Krisciunas et al. (2007)**

## The Value of Optical + NIR Photometry for Deducing Host Galaxy Extinction 

**2004S vs. 2001el**

**Krisciunas et al. (2007)**

**The Value of Optical + NIR Photometry for Deducing Host Galaxy Extinction **

## The Value of Optical + NIR Photometry for Deducing Host Galaxy Extinction 

**The Value of Optical + NIR Photometry for Deducing Host Galaxy Extinction **

*  *Monte Carlo simulation of 30,000 events
-  Probability distribution of AV from Jha et al. (2006)
-  RV has a probability distribution with a mean of 2.4 and std. dev. of 0.4

**Krisciunas et al. (2007)**

## The Best Way to Determine Host Galaxy Dust Properties:

**  ****The combination of ****UV, optical, and NIR photometry**** will allow ****both A****V**** and R****V**** to be determined for each SN**
**  ****Within the next few years, the Carnegie Supernova Project and the Harvard-CfA program will obtain UV to NIR photometry of ****200+ low-z SNe Ia**
**  ****It is important that similar data be obtained for ****high-z SNe**** (the JEDI JDEM mission would have done this...)**