Collaborators:

K. Krisciunas (CTIO/Carnegie), N. Suntzeff (CTIO)
M. Hamuy (Carnegie), E. Persson (Carnegie),
W. Freedman (Carnegie), M. Roth (Carnegie)


L. Germany (ESO)
Outline of Talk:
 SNe Ia
 Morphology of NIR light curves
 Light curve templates
 Colors & Reddening
 Absolute magnitudes & Hubble diagram
 SNe II
 A few words about Reddening Determinations
UBVRIJHK Light Curves of a Typical SN Ia
Primary
maximum
Secondary
maximum
Sources:
UBVRI: Suntzeff et al. (1999)
JHK:
Mayya et al. (1998)
Jha et al. (1999)
Hernandez et al. (2000)
SN m15(B)
•
Secondary maximum
occurs later for slower
declining SNe
•
Generally speaking,
secondary maximum is
stronger for slower
declining SNe
Y band at 1.035 µm
Secondary maximum
appears to have been
significantly stronger than
primary maximum!
Strength of Secondary Maximum vs.
Decline Rate in the I Band
Krisciunas et al. (2001)
Krisciunas et al. (2001)
Morphology of JHK lightcurves of SNe Ia:
 Primary maxima occur a few days before T(Bmax)
 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(Bmax)
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
Let’s zoom in on this
time window, and do
this more precisely
(e.g., include K
corrections)
Construction of JHK Stretch Templates
SN m15(B)
= 1980N (1.29)
= 1986G (1.79)
= 1998bu (1.05)

= 1999aw (0.81)
= 1999ee (0.94)
= 2000ca (1.01)
= 2001el (1.15)
Krisciunas et al. (2004)
Fitting JHK Light Curves with the Stretch Templates
m15(B) = 0.99
m15(B) = 1.73
Fitting JHK Light Curves with the Stretch Templates
m15(B) = 1.28
m15(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(Bmax)
 Allows reasonable estimates to be made of the
maximum light magnitudes in JHK without the need to
actually obtain photometry at maximum light
 The same technique can most likely be extended to the
I band as well (useful for observations of high-z SNe Ia)
The B-V Color Evolution of
Unreddened SNe Ia
From: Phillips et al. 1999
The B-V Color Evolution of
Unreddened SNe Ia
From: Phillips et al. 1999
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
"Realistic Case Optical"
Av = (2.6±0.3) x E(B-V)
"Worst Case NIR"
Av = (1.126±0.072) x E(V-K)
"Best Case Optical"
Av = (3.1±0.1) x E(B-V)
Krisciunas et al. (2000)
Optical-NIR Colors of
Unreddened SNe Ia
SNe Ia with
0.9 < m15(B) < 1.3
Shifted to Av = 0.0
locus
Krisciunas et al. (2000)
Optical-NIR Colors of
Unreddened SNe Ia
SNe Ia with
0.8 < m15(B) < 1.0
Shifted to Av = 0.0
locus
SNe Ia with
0.9 < m15(B) < 1.3
Krisciunas et al. (2004)
Optical-NIR Colors vs. Δm15(B)
Unreddened SNe Ia
Scatter corresponds to
± 0.18 mag in Av
Equivalent to ± 0.06
mag in E(B-V)
This is as expected
since reddening
corrections were
derived from BVI data
Krisciunas et al. (2004)
Reddening:
 SNe Ia with intermediate decline rates
(0.9 < m15(B) < 1.3) have similar V-IR
color evolution
 As expected, the V-IR color evolution of
slower declining (0.8 < m15(B) < 1.0)
events is somewhat bluer
 Use of optical-IR color evolution to
determine reddening should ultimately
prove more precise than optical-only colors
Absolute Magnitudes of SNe Ia
Note that the
luminosity
vs. decline
rate relaton in
H may be flat
Phillips et al.
(2003)
Are SNe Ia “Perfect” Standard Candles
in the NIR?
• We can try to answer this question by constructing
Hubble diagrams in JHK
• Available data: 7 SNe Ia observed at LCO and CTIO
+ 9 SNe Ia with previously published photometry
• Use stretch template fits to find maximum light
magnitudes
• Correct for reddening based on E(B-V) values
determined from BVI photometry
• K corrections calculated from NIR spectra of SN
1999ee (Hamuy et al. 2002)
JHK Hubble Diagrams of SNe Ia
Cepheid & SBF
distances used to
derive “equivalent”
v(cmb) assuming
Ho = 72
Are the deviations
from the Hubble
lines a function of
m15(B)?
 = 0.14 mag
 = 0.18 mag
 = 0.12 mag
Krisciunas, Phillips, & Suntzeff (2004)
NIR Absolute Magnitudes of SNe Ia
Within the precision of
the observations, there
are no obvious decline
rate relations in the NIR
Mean values:
M(J) = -18.57 ± 0.14
M(H) = -18.24 ± 0.18
M(K) = -18.42 ± 0.12
Krisciunas, Phillips, & Suntzeff (2004)
Absolute Magnitudes &
Hubble Diagrams:
 While SNe Ia are standardizable candles in the
optical bands, they apparently are standard candles
in the NIR at the ± 0.20 mag level or better (± 9% in
distance)
 The one disadvantage of the NIR is that SNe Ia are
 1 mag less luminous in JHK than they are in the V
band
What about SNe II in the NIR?
• Plateau SNe (SNe II-P) are potentially useful distance indicators
• EPM (the models need more work)
• The Luminosity vs. Velocity Relation (looks encouraging)
• Major source of error is determining the dust reddening
• Since electron scattering is dominant opacity during plateau
phase, SNe II-P should have similar similar hydrogen
recombination tempertures during last part of plateau phase
• As in the case of SNe Ia, Optical-NIR colors offer significant
promise for improving reddening estimates of SNe II-P
NIR Light Curves of a Plateau SN II
SNe II-P are relatively
bright in the NIR, with
maximum occurring
typically 2 months after
explosion
Hamuy et al. (2001)
Comparison of B-V and V-I Color Evolution:
SN 1999gi
SNreddening
1999ee
Color
curvesvs.
and
Av=0.85
color
Av=0.50
B-V
V-I
time since explosion (days)
Hamuy (2002)
Comparison of B-V and V-I Color Evolution:
SN
1999cr
SNreddening
1999ee
Color
curvesvs.
and
Av=0.10
B-V
V-I
color
Av=-0.75
time since explosion (days)
Hamuy (2002)
Comparison of B-V and V-I Reddening
Reddening
Estimates
Determinations
(Relative
to SN 1999em)
•
In many cases, values
based on B-V are
negative – differing
metallicities may be
responsible for this
•
Values based on V-I
appear to be better
behaved
•
V-NIR colors may give
best estimates of all
Hamuy (2002)