Title: Short-Duration Gamma-Ray Burst Central Engines
1Short-Duration Gamma-Ray Burst Central Engines
Brian Metzger
Princeton University
In collaboration with
Eliot Quataert (Berkeley) Todd Thompson (Ohio
State) Tony Piro (Berkeley) Niccolo Bucciantini
(Nordita) Almudena Arcones (MPIK) Gabriel
Martinez-Pinedo (MPIK)
Chandra / Einstein Fellows Symposium Harvard
CfA, October 27 2009
2 Gamma-Ray Bursts Long Short Duration
BATSE GRBs
Nakar 07
3 Gamma-Ray Bursts Long Short Duration
BATSE GRBs
Long
- High Redshift, zavg 2
- Large Energies (Eiso1052-54 ergs)
- Star-Forming Host Galaxies
- Type Ic Broad-Line Supernovae
Nakar 07
4 Gamma-Ray Bursts Long Short Duration
BATSE GRBs
Long
- High Redshift, zavg 2
- Large Energies (Eiso1052-54 ergs)
- Star-Forming Host Galaxies
- Type Ic Broad-Line Supernovae
Nakar 07
Nakar 07
Short
5Merging Compact Objects (NS-NS or BH-NS)
Paczynski 1986 Goodman 1986 Eichler1989
Narayan 1992,
t 0.7 ms
Inspiral Chirp Gravitational Waves
t 3 ms
Shibata Taniguchi 2006
- Target for Advanced LIGO
- Disk left behind w/ mass 10-3 - 0.1 M? size
10-100 km - ? cooling via
neutrinos (?? gtgt1, ?? 1 )
6Accretion-Induced Collapse (AIC)
- Binary Accretion or WD-WD Merger
- Failed Type Ia SN
- Collapse of rapidly-rotating WD ? Disk around
PNS Mdisk 10-2 - 0.3 M?
Circinus X-1 (Chandra)
Neutron Star Circinus X-1 ? gt 15 ! (Fender et
al. 2004)
7Similar Systems - Distinct Origins
NS-NS / BH-NS Mergers
BH
M 0.01-0.1 M? R 100 km
Accretion-Induced Collapse
NS
consistent with short GRB durations
8GRB050509b
Short GRB Host Galaxies
GRB050709
z 0.16 SFR 0.2 M? yr-1
Bloom 06
z 0.225 SFR lt 0.1 M? yr-1
KECK Bloom06
HUBBLE Fox05
GRB050724
Berger 05
z 0.258 SFR lt 0.03 M? yr-1
Berger05
9GRB050509b
Short GRB Host Galaxies
GRB050709
z 0.16 SFR 0.2 M? yr-1
Bloom 06
No Supernova!
z 0.225 SFR lt 0.1 M? yr-1
KECK Bloom06
HUBBLE Fox05
- Lower redshift (z 0.1-1)
- Eiso 1049-51 ergs
- Older Progenitor Population (Consistent with
being drawn from field galaxies Berger 09)
GRB050724
Berger 05
GRB050724
z 0.258 SFR lt 0.03 M? yr-1
Berger05
10Short GRBs with Extended X-Ray Emission
25 of Swift Bursts (2 classes?) Similarity
To GRB ? Ongoing Engine Activity EEE/EGRB 1-30
!
GRB050709
GRB080503
SEE/SGRB 30
Perley et al. 2008
BATSE Examples (Norris Bonnell 2006)
11Evolution of the Remnant Disk
Metzger, Piro, Quataert 2008, 2009 (see also
Beloborodov 2009 Lee et al. 2009)
Local Disk Mass ??r2 (M?)
1-D Time-Dependent Models (?
viscosity realistic ?-cooling)
12Late-Time Outflows
Metzger et al. 2008, 2009
At t 0.1-1 seconds R 500 km, M 0.3
Minitial, T 1 MeV
- ?-Particle Formation
- Thick Disks Marginally Bound
- (Narayan Yi 94 Blandford Begelman 99)
EBIND GMBHmn/2R 3 MeV nucleon-1
Powerful Winds Blow Apart Disk
?
?ENUC 7 MeV nucleon-1
BH
20-40 of the Initial Disk is Ejected Back into
Space!
13???
14Tidal Tails in NS-NS/NS-BH Mergers
Lee Ramirez-Ruiz 07
Tail(s) with 10 prompt disk mass
15Late-Time Fall-Back Accretion
(Rosswog 07 Faber06 Lee09)
a
Rosswog 07
16r - Process Heating (not included in present
simulations!)
Decompressing NS Matter ? A 100 Nuclei Free
Neutrons (Lattimer77 Meyer 89)
Protons
Neutrons
?Er 1-3 MeV nucleon-1 released over ?theat 1
second
17r-Process Network Calculations
Metzger, Arcones, Quataert, Martinez-Pinedo 2009
a
18Total r-Process Heating Along Fall-Back Orbits
Orbital Period
Binding Energy of Merger Ejecta
19theat gt 1 s
theat lt 1 s
a
a
torb 1 s
20theat gt 1 s
theat lt 1 s
a
a
torb 1 s
No Late Fall-Back
21theat gt 1 s
theat lt 1 s
a
a
torb 1 s
Gap
No Late Fall-Back
22The Effects of r-Process Heating on Fall-back
Accretion
Metzger, Arcones, Quataert, Martinez-Pinedo 2009
Either Complete Suppression of Fall-Back after t
1 sec OR Gap of ?t seconds opened
23???
24Magnetar Spin-Down
?
Following
- Accretion-Induced Collapse
- NS-NS Merger with long-lived NS remnant
NS
25Magnetar Spin-Down
?
Following
- Accretion-Induced Collapse
- NS-NS Merger with long-lived NS remnant
NS
High ?
Low ?
Internal Shock Emission
Power (1051 ergs s-1)
P0 1 ms
1016 G
GRB060614 Overlaid
3 1015 G
Metzger, Quataert Thompson 08
? ?
1015 G
26Conclusions
- Swift Revolution Afterglows and Host Galaxies
- ? long and short GRBs have distinct progenitors
- NS-NS/NS-BH Remains Promising Model
- ? consistent w/ host galaxies, durations,
energetics - accretion disk spreads, explodes at t 1 second.
- ? 100 second X-ray Emission Major Problem
- Oft-Discussed Explanation Fall-Back Accretion
- r-process heating must be taken into account
- ? either natural explanation or makes matters
worse - AIC Promising Alternative Model (NS Remains!)
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