Transcript Ay123 Lecture I - Physical Properties

Ay 123: Supernovae contd..
Nucleosynthesis - revisited
Fe
peak
Z
Z
N
Hydrostatic equilibrium slowly builds
up He4 through Fe56
Equilibrium `e-process’ postulated
to explain `Fe peak’ abundances:
more stable = more abundant
A
Decay of Nuclei and SN II light curves
Ni56 t=6.1d
Co56 t=77d
SN1987A: McCray ARAA 31, 175 (1993)
The Ring Around SN1987A
Original FOC image (1990)
Post-repair image
1.66”
IUE observes a brightening in UV emission
lines 413d after SN explosion - pre-SN ejecta
is being illuminated by the explosion.
Resolving the diameter of the ring gives its
size and an absolute distance to the LMC
Panagia et al Ap J 380, L29 (1991)
Cosmological Distances from SN II P
Flux, temperature & expansion velocity during `plateau phase’
Hubble Diagram for SNe IIP
scatter = 0.26 mag
(for Ia scatter~0.20)
Could detect acceleration with present technology (~15 SNIIP)
More effectively probe to high z with JWST/TMT (Nugent et al 2006)
SN Ia Light Curve Shape - Luminosity Correlation
Reduces scatter on `Hubble diagram’
No correction
Correction
Phillips 1993 Ap J 413, L105; Riess et al 1995 Ap J 438, 17
Host Galaxy Dependence of SNe Ia Properties
Ia rate
SFR/mass
Width of light curve
SN Ia rate correlates with specific SFR of host galaxy
Light curve `stretch’ likewise correlates
SN properties depend on mix of stellar population
Sullivan et al Ap J 648, 868 (2006)
Routes to a SNeIa in single degenerate C-O WD systems
(Nomoto et al astro-ph/9907386)
AGB with
C+O core
RG+He
core
WD + MS in
common
envelope
WD + red giant
Wind reduces
rate
Short time delay
Significant time delay
Cosmic Acceleration From SNe Ia
Perlmutter et al 1999
• Light curve corrected peak luminosities give luminosity distance
• Redshifts give cosmic expansion velocities
• SNe Ia are too faint for a given redshift c.f. decelerating models!
Implications of Cosmic Acceleration
Why not ? two puzzles:
• expect =
8GmP4
Perlmutter et al 1999
(10120 larger)
• Why acceleration now?
M  R-3 (matter)
vac = const (vacuum)
Alternative: new physics - “dark energy”:
quintessence: equation of state p = w ;  R-3(1+w)
dynamical scalar field w = w(t)
Deep HST Survey
Riess et al Ap J 659, 98 (2007)
First Year Results from CFHT SNLS
Astier et al A&A 447, 31 (2006)
71 homogenously studied SNe Ia
w = -1.023 ± 0.090
i.e. equivalent to Cosmological
Constant