Ay 123: Supernovae contd..

Nucleosynthesis - revisited

Hydrostatic equilibrium slowly builds up He4 through Fe56

Equilibrium `e-process’ postulated to explain `Fe peak’ abundances: more stable = more abundant

Z

N

Z

Fe peak

A

Decay of Nuclei and SN II light curves

SN1987A: McCray ARAA 31, 175 (1993)

Ni56 t=6.1d

Co56 t=77d

The Ring Around SN1987A

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

Original FOC image (1990)

Post-repair image

Panagia et al Ap J 380, L29 (1991)

1.66”

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 CorrelationReduces scatter on `Hubble diagram’

Phillips 1993 Ap J 413, L105; Riess et al 1995 Ap J 438, 17

No correction

Correction

Host Galaxy Dependence of SNe Ia Properties

Ia rate

SFR/mass

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)

Width of light curve

Routes to a SNeIa in single degenerate C-O WD systems (Nomoto et al astro-ph/9907386)

WD + red giant

Wind reduces rate

Short time delay

WD + MS in common envelope

AGB with C+O core

RG+He core

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 AccelerationImplications of Cosmic Acceleration

Perlmutter et al 1999Why not ? two puzzles:

• expect = 8GmP4

(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)

Riess et al Ap J 659, 98 (2007)

Deep HST Survey

First Year Results from CFHT SNLSAstier et al A&A 447, 31 (2006)

71 homogenously studied SNe Ia

w = -1.023 ± 0.090

i.e. equivalent to Cosmological Constant