Ay 123 Lecture 11 - Supernovae & Neutron Stars Timescales for HS Burning faster and faster..
Jan 17, 2016
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