Ay 123 Lecture 11 - Supernovae & Neutron Stars
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Transcript of Ay 123 Lecture 11 - Supernovae & Neutron Stars
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)