Ay 123 Lecture 11 - Supernovae & Neutron Stars

Timescales for HS Burning

faster and faster..

Structure of Massive Star at End of HS Burning

Delayed Explosions

Neutrino Trapping

Neutrinos Arrive from SN1987A

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

Supernova Discovery Statistics - I

Zwicky + Amateurs

KAIT

High-Z Searches

SNf and SDSS & SNLS

Calán-Tololo Search

PTF, LSSN, CRTS (~700/yr)

Supernova Discovery Statistics - II

Supernovae Light Curves

II Plateau

II Linear

Ia

Doggett & Branch AJ 90, 2303 (1985)

Decay of Nuclei and SN II light curves

SN1987A: McCray ARAA 31, 175 (1993)

Ni56 t=6.1d

Co56 t=77d

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)

Routes to a SNeIa in degenerate C-O WD systems

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

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

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)