The Nature of Cosmic Explosions
Avishay Gal-Yam, Caltech 2007
Cosmic Explosions
Type II Supernova
Type Ia Supernova
SN 1994D, Challis
Short GRB
SN 1987A
A singular,
catastrophic stellar
event
Long GRB
?
SHB 050709, Fox et al. 2005
GRB 980425, Galama et al. 1998
Type Ia Supernovae:
what we know
Old stellar populations: progenitors
are not young/massive
Sollerman et al. 2004
No signatures of H, He: evolved
Total energy consistent with a ~1.4
Mo WD (E=Enuc-Ebind)
Spectra and light curves well fit by
WD models
Homogeneity naturally explained
by critical Chandrasekhar mass
“Smoking gun” evidence: -rays
requires NUSTAR+luck …
Sauer et al. 2005
Gal-Yam
Immler etetal.
al.2006
2003
SNe Ia are most likely thermonuclear explosions of WDs
Type Ia Supernovae:
main puzzle
SD
DD
Donor ?
Strong motivation from cosmology
Type Ia Supernovae:
observational handles
Direct progenitor detection: unlikely – maybe in our galaxy
Indirect methods:
SN remnants: a promising approach
SN Rates: the progenitor delay time
Progenitor mass loss
Type Ia Supernovae:
remnants
Ruiz Lapuente et al.
Schmidt et al,
Gal-Yam et al.
Galactic type Ia SNRs are well
observed
Models claim to constrain SN
Ia explosion mechanism
Ruiz Lapuente 2004
These conclusions depend on:
(1) Tycho was a Ia and
(2) complex models
Badanes et al. 2005,2006,2007
Search for Tycho’s companion
is ongoing
SNRs in the LMC provide an
exciting prospect
Type Ia Supernovae:
rates
Comparison of SN rates with
star formation rates constrains
progenitor lifetime
Most SNe Ia are young!
There are probably two
populations (young and old)
SN Ia rates in galaxy clusters
probe the old component
This is complicated and model
dependent
Mannucci et al. 2005
Gal-Yam, Maoz & Sharon 2002;
Sharon et al. 2007; Sharon, GalYam in prep (HST cycles 14,15)
Sullivan et al. 2006,
also: Mannucci et al.,
Scannapieco & Bildsten
Type Ia Supernovae:
progenitor mass loss
Single degenerate models: accretion leads to mass loss
Limits/detection will provide a strong indication for SD/DD
- Radio (Panagia et al. 2006): < 3 x 10-8 solar/year
- X-ray (Immler et al. 2006): < 10-6 solar/year
- Optical lines (H, He; Mattila et al. 2005): < 10-5 solar/year
Type Ia Supernovae:
absorption spectroscopy
SN 2006X in M100: variable
Sodium absorption (VLT, Keck)
Calcium lines are unchanged:
change not due to line of sight
Photoionzation+recombination+
interaction model proposed
Additional examples?
Aspherical model: 20-30% cover
Patat et al., Science
SN 2007af
Gal-Yam, Simon,
Penprase, Sargent
Ongoing Keck investigation
Single degenerate model put to the test
Type Ia Supernovae:
bottom line
This is a difficult problem, but we are getting there
Core Collapse Supernovae:
what we know
Type II-P
SN 1987A, LMC, White & Malin
Fe core
Exploding massive stars
-flash as expected from Fe
core-collapse models
Extreme heterogeneity
SN 1987A
(faint, slow)

Type IIn
(dense CSM)

Type IIL/IIb
(little H)

Type Ib
(H, He)
Type Ic (He)
GRB/XRF
Core Collapse Supernovae:
main puzzles:
(1) Relate SN to progenitor
Redthey all fundamentally the same?
(2) Are
Type II-P
Supergiant
Blue
Supergiant
SN 1987A
(faint, slow)
Luminous
Blue
Variables
Early W-R
(He, N)
Type IIn
(dense CSM)
Late W-R
(C, O)
Type Ib
(H, He)
Massive
Binaries
Type IIL/IIb
(little H)
Type Ic (He)
GRB/XRF
Core Collapse Supernovae:
progenitor hunting
LGS, Kp, Nov. 10, 2005
Observing SN progenitors requires:
(1) Luck: deep pre-explosion images
(2) Precise SN localization (HST)
We can do (better) with AO
F547M SNe per year
About HST,
2 nearby
(Gal-Yam et al. 2005; 2007, Leonard
et al. 2007)
SN 2004gt; Gal-Yam et al. 2005
The Progenitor – SN Map
Red
Supergiant
Type II-P
Blue
Supergiant
SN 1987A
(faint, slow)
LBV
( Car)
SN 2005gl
Gal-Yam et al. 2007
Type IIn
(dense CSM)
Late W-R
(WN)
Type IIL/IIb
(little H)
Early W-R
(WC/WO)
Type Ib
(H, He)
Massive
Binaries
Type Ic (He)
Core Collapse Supernovae:
are they all the same?
Jets?
Acoustic oscillations?
Pair-production SNe?
SN inner workings are hidden
from EM eyes – but visible in
other ways
The nearest SNe: Neutrinos
and gravitational Waves
Nearby SNe are strong  sources
Precise timing can push SN
detection out to a few Mpc with
future facilities (perhaps even
Super-K; Ando et al.)
Some (controversial) models
predict similar prospects for
LIGO
Again, timing can help a lot
Burrows et al. 2006
NO SWEAT
Neutrino-Oriented SN Whole-Earth Telescope
ANU
?
Wise Observatory
ROTSE III
KAIT
PAIRITEL
Israel
(Australia, Texas,
Lick Observatory
Mt. Hopkins, Arizona
Namibia, Turkey)
California
?
Core Collapse Supernovae:
something new?
Most nearby SNe are found in
targeted searches of luminous
galaxies
Blind surveys find new types of
supernovae in faint hosts
Are these fundamentally new?
Yes! (Smith et al. 2007; PP)
Maybe (Ofek et al. 2007)
The SN factory gives interesting
clues …
Ofek et al. 2007
?
The PTF
There is nothing like searching, if you want to find something.
You usually find something, if you search,
but it is not always quite the something you were after.
Thorin Oakenshild
Gamma-Ray Bursts:
What do we know?
Observationally split into shorthard and long-soft
Similar high energy properties
suggest similar physics at work
(e.g., review by Nakar 2007)
Attractive possibility: accretion
onto black holes
Different time scales determined
by mass sources: NS (short) vs.
stellar fallback (collapsar, long)
(Narayan, Piran & Kumar 2001)
Gamma-Ray Bursts:
what we know
Long GRBs come from massive
stars going SN
Short GRBs are not associated
with massive stars
Looks good. All done?
Gamma-Ray Bursts:
not done yet
GRB 060614 was a long GRB (100s),
with no SN, and probably not associated
with massive stars similar to other long
events (Gal-Yam et al. 2006, Nature)
“GRB 060614 requires a novel
explosive mechanism” (long-short? SNless long? Something else?)
?
You usually find something, if you search,
but it is not always quite the something you were after.
Thanks