Ay 123 Lecture 11 - Supernovae & Neutron Stars

Timescales for HS Burning

faster and faster..

Structure of Massive Star at End of HS Burning

Neutrinos Arrive from SN1987A

Hirata et al Phys. Rev. Lettt 58, 1490 (1987)

Neutrino Trapping

Supernova Discoveries

Supernovae Light Curves

II Plateau

II Linear

Ia

Doggett & Branch AJ 90, 2303 (1985)

Supernovae Spectra

Thermonuclear:

Type Ia: Si, no H

Core Collapse:

Type II: H emission

Type Ib: He, weak H

Type Ic: no H, no He

Review: Filippenko, ARAA 35, 309 (1997)

Origin of `P Cygni’ Profile

P Cygni: luminous blue variable with blue-shifted (absorbing) outflow against core emission

Delayed Explosions

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 Correlation

Reduces 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 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