The Central Engines of Short Duration
Gamma-Ray Bursts
NS⇔NSNS⇔

BH

Brian Metzger
Columbia University
In Collaboration withEdo Berger, Wen-Fai Fong (Harvard), Tony Piro, Dan Perley (Caltech)
Almudena Arcones, Gabriel Martinez-Pinedo (Darmstadt), Todd Thompson (OSU)
Rodrigo Fernandez, Eliot Quataert, Dan Kasen, Geoﬀ Bower (UC Berkeley)
Indrek Vurm, Romain Hascoet, Andrei Beloborodov (Columbia), N. Bucciantini (INAF)“Gamma-Ray Bursts” November 14, 2013 - YITP, Kyoto, JapanNeutron Star Binary Mergers“Advanced” LIGO/Virgo (>2016)
Range ~ 200-500 Mpc
Detection Rate ~ 1-100 yr-1

Ω
NSNSBHNSSky Error Regions ~ 10-100 deg2

LIGO (North America)⇒ ~ 103-104 galaxies

Nissanke et a. 2011

Virgo (Europe)Astrophysical Origin of R-Process Nuclei
Core Collapse Supernovae or NS Binary Mergers?
Galactic r-process rate:#7-1
˙M~5"10M
yrA >130!
(Qian et al. 2000)

Requires (e.g. Hoffman et al. 1997)(1) low Ye (2) high entropy (3) fast expansion

Fraction of r-Processfrom NS Mergers:# N˙ merge&# M ej&fR ~ %("4-1 (%"210 yr '$ 10 M!'$Numerical Simulation - Two 1.4 M NSs
Courtesy M. Shibata (Tokyo U)

Electromagnetic Counterparts of NS-NS/NS-BH Mergers
Afterglow

Short
GRB
‘Kilonova’Metzger & Berger 2012Electromagnetic Counterparts of NS-NS/NS-BH Mergers
Afterglow

Short
GRB
‘Kilonova’Metzger & Berger 2012

Numerical Simulation - Two 1.4 M NSs
Courtesy M. Shibata (Tokyo U)

Remnant Accretion Disk(e.g. Ruffert & Janka 1999; Shibata & Taniguchi 2006; Faber et al. 2006; Chawla et al. 2010; Duez et al. 2010; Foucalt 2012; Deaton et al. 2013)

Lee et al. 2004••••

Disk Mass ~0.01 - 0.1 M & Size ~ 10-100 km
Hot (T > MeV) & Dense (ρ ~ 108-1012 g cm-3)
Neutrino Cooled: (τν ~ 0.01-100)
Equilibrium e + + n " # e + p vs. e" + p # $ e + n ⇒ Ye ~ 0.1
˙ ~ 10 "2 "10M! s-1
Accretion Rate M
1/ 2)1

3/2" M• % " ( % " Rd % " H /R %t visc ~!0.1 $' $'' $ ' $ !
# 3M! & # 0.1& #100 km & # 0.5 &!

)2s

Short GRBEngine?

Relativistic Jets and Short GRBs

ν PoweredOR

Aloy et al. 2005

Rezzolla et al. 2010

MHD PoweredRelativistic Jets and Short GRBs

woHB]
leac d?
Sge rater
La ene[is Gν Powereddle
i-F

OR-ra

X
(!

ciffe
Intnieyralfe)?
sAloy et al. 2005

Rezzolla et al. 2010

MHD PoweredθjSwift Short
GRBs
Metzger & Berger 2012

Detection Rate >z (yr -1)

Short GRBs Rare within aLIGO/Virgo Volume!!!

Redshift z2%($j$jf" ~ 3.4 # 2 ~ 0.07' *& 0.2 )2

Detectable fraction by all sky γ-ray telescope

Relativistic Blastwave

Zhang & MacFadyen 2009

Electromagnetic Counterparts of NS-NS/NS-BH Mergers
Afterglow

ShortGRB‘Kilonova’Metzger & Berger 2012

ModelNeutron-Rich Ejecta(e.g. Janka et al. 1999; Lee & Kluzniak 1999; Ruffert & Janka 2001; Rosswog et al. 2004; Rosswog 2005; Shibata &Taniguchi 2006; Giacomazzo et al. 2009; Duez et al. 2010; East et al. 2012; Hotokezaka et al. 2013; Bauswein+13)

Full GR / Simple EOS / Circular

Mej ~ 10-4 - 0.1 M

npYe "# 0.05n p + nn

Newtonian / Realistic EOS / Eccentric!

Hotokezaka et al. 2013

Dynamical Tidal Tails

Mej (10-3 M)ModelNeutron-Rich Ejecta(e.g. Janka et al. 1999; Lee & Kluzniak 1999; Ruffert & Janka 2001; Rosswog et al. 2004; Rosswog 2005; Shibata &Taniguchi 2006; Giacomazzo et al. 2009; Duez et al. 2010; East et al. 2012; Hotokezaka et al. 2013; Bauswein+13)

Full GR / Simple EOS / Circular

Mej ~ 10-4 - 0.1 M

npYe "# 0.05n p + nn

Newtonian / Realistic EOS / Eccentric

Disk Outflows!
Neutrino-Powered (Early)(e.g. McLaughlin & Surman 05; Surman+08; BDM+08; Dessart+09; Wanajo & Janka 12)

Recombination-Powered (Late)(e.g. Beloborodov 08; BDM+08,BDM+08, 09; Lee+09; Fernandez & BDM 13)

Ye ~ ???

Mej = fwMd ~ 10-3-10-2 (fw/0.1) M
!

Hotokezaka et al. 2013

Dynamical Tidal Tails

Mej (10-3 M)as used in Metzger et al. 2010 (movie courtesy A. Arcones & G. Martinez-Pinedo)

R-Process Network (neutron captures, photo-dissociations, α- and β-decays, fission)

Radioactive Heating of Merger Ejecta(BDM et al. 2010; Roberts et al. 2011; Goriely et al. 2011; Korobkin et al. 2012; Bauswein et al. 2013)

Ye = 0.1

Dominant β-Decays at t ~ 1 day: 132,134,135 I, 128,129Sb,129Te,135Xe
Relatively insensitive to details (Ye, expansion history, NSE or not)BDM et al. 2010

∝ t-1.3

Bolometric Luminosity“kilo-nova”

Color Evolution
Fe Opacity
BDM et al. 2010Blackbody Model

High Opacity of the Lanthanides(Kasen et al. 2013; Tanaka & Hotokezaka 2013)

Kasen et al. 2013

lanthanides“Fe”
Tanaka & Hotokezaka 2013Bolometric Luminosity“kilo-nova”

Color Evolution
Fe Opacity
BDM et al. 2010Blackbody ModelFe Opacity
BDM et al. 20100.
3e <Y0.
3Blackbody Modele >“kilo-nova”

Color Evolution

Y

Bolometric LuminosityModelNeutron-Rich Ejecta(e.g. Janka et al. 1999; Lee & Kluzniak 1999; Ruffert & Janka 2001; Rosswog et al. 2004; Rosswog 2005; Shibata &Taniguchi 2006; Giacomazzo et al. 2009; Duez et al. 2010; East et al. 2012; Hotokezaka et al. 2013)

Full GR / Simple EOS / Circular

Mej ~ 10-4 - 0.1 M

Ye " 0.05Newtonian / Realistic EOS / Eccentric

Disk Outflows!
Neutrino-Powered (Early)(e.g. McLaughlin & Surman 05; Surman+08; BDM+08; Dessart+09)

Recombination-Powered (Late)

Ye ~ ???

(e.g. Beloborodov 08; BDM+08,BDM+08, 09; Lee+09; Fernandez & BDM 13)

Mej = fwMd ~ 10-3-10-2 (fw/0.1) M
!

Hotokezaka et al. 2013

Dynamical Tidal Tails

Mej (10-3 M)Numerical Simulation - Two 1.4 M NSs
Courtesy M. Shibata (Tokyo U)

Two Component
Light CurveBlue

RedBarnes & Kasen 2013
See also Grossman+13
tidal tail:r-processordisk winds:
r-process or Fe?

!

!

Metzger, Piro & Quataert 2008, 2009

Angular Momentum("# 3 " % 1/ 2 "1/ 2=r($#r )*)"t r "r '& "rEntropy

Local Disk Mass Σπr2 (M)

Viscous Evolution of theRemnant Disk

BHdS
T= q˙ visc " q˙#dt
t = 0.01 s
Heating

Cooling

Nuclear Composition,&1 % X f )/dYe
= ( "e + n # p$ + "e % p # n$ ) .1 % Ye % (+1dt' 2 *0-t=1s

Delayed Disk Winds (‘Evaporation’)
After t ~ 1 seconds, R ~ 300 km & T < 1 MeV• Recombination: n + p ⇒ He
EBIND ~ GMBHmn/2R ~ 5 MeV nucleon-1
ΔENUC ~ 7 MeV nucleon-1• Thick Disks Marginally BoundDelayed Disk Winds (‘Evaporation’)
After t ~ 1 seconds, R ~ 300 km & T < 1 MeV• Recombination: n + p ⇒ He
EBIND ~ GMBHmn/2R ~ 5 MeV nucleon-1
ΔENUC ~ 7 MeV nucleon-1• Thick Disks Marginally Bound}⇒ Disk BlowsApart

BH

Sizable Fraction of Initial Disk Unbound!

Axisymmetric Torus Evolution(Fernandez & Metzger 2012, 2013)• P-W potential with MBH = 3,10 M• hydrodynamic α viscosity• NSE recombination 2n+2p ⇒ 4He

Equilibrium Torus
Mt ~ 0.01-0.1 M
R0 ~ 50 km
uniform Ye = 0.1• run-time Δt ~ 1000-3000 torb
• neutrino self-irradiation: “light bulb”+ optical depth corrections:angular emission
patternpeak emission

R ∈ [2,2000] Rg
Nr = 64 per decadeNθ = 56

Late Disk Outflows (Evaporation)
˙ out (with " recombination)
M

˙ BHM

˙ out (NO " recombination)
M!
!

!
Time (s)• unbound outflow poweredby α recombination andviscous heating• neutrino heating
subdominantLate Disk Outflows (Evaporation)
˙ out (with " recombination)
M

˙ BHM

˙ out (NO " recombination)M!
!

!

• unbound outflow poweredby α recombination andviscous heating• neutrino heating
subdominantTime (s)outflow robust}

Mej ~ 0.05 - 0.2 Mt
Vej ~ 0.1 c

Ye Freeze Out
t = 0.3 st=3st = 0.03 s

Mass per bin (M)

Outflow Composition
entropyYe# S & "3 / 2&"1/ 2 # tfX He~ 10 "2 %(1 " 2Ye ) % 0.1exps (-1 ($'$ k b nuc '‘seed’ nuclei form (T<5×109 K)!

then α-process (Woosley & Hoffman 92)
n> 100 " A > 130seed⇒ r-process (including lanthanides)!

texpXHeComposition (Preliminary)Implications of Neutron-Rich Outflows• Robust heavy r-process source (distinct from dynamical ejecta)#7-1
˙ AGalacticM>130 ~ 5 " 10 M ! yr(Qian 2000)• Disk outflow emission hard to distinguish from tidal taildisk windtidal tailBarnes & Kasen 2013

Grossman et al. 2013

! and long (~WEEK) kilonova– High opacity of lanthanides ⇒ both produce RED(cf. Berger+13; de Ugarte Postigo+13 ; Fong+13 )0.1 M

0.01 MIf true, confirms association of short GRBs and NS-NS mergers

(see also Berger+13; de Ugarte Postigo+13; Fong+13 )Implications (if true)• confirms association of shortGRBs with NS mergers

0.1 M

• counterpart would ~21-22
mag at 200 Mpc (detectablewith big glass)• minimum r-processcontribution from NS mergers
RSGRB " M ejn gal
10 #8 Mpc -3 yr -1 " 0.03M!
~0.03 gal Mpc -3
˙ MW~ 10 #8 M! yr -1 gal-1 ~ 0.02 M
˙r ~M

0.01 MTwo Component
Light Curve

Blue



RedBarnes & Kasen 2013
Grossman+13








tidal tail:r-process

ordisk winds:
r-process or Fe?

Two Component
Light Curve

Blue



Red

Barnes & Kasen 2013
Grossman+13








tidal tail:r-processdisk winds:
r-process or Fe ?

Two Component
Light CurveBlue



RedBarnes & Kasen 2013
Grossman+13








tidal tail:r-processordisk winds:
r-process or Fe ?

Two Component
Light CurveBlue



RedBarnes & Kasen 2013
Grossman+13νννNStidal tail:r-processdisk winds:
r-process or Fe ?

ν" e + n #e $ + p

Neutrino Luminosity (erg s-1)

Neutrinos from NS Remnant
Prompt BH(Fernandez & BDM 13)

Cooling NS
Disk outflow composition
0.4

Ye

0.3

Time after merger (s)0.2

See talk by Albino Perego~ms~100 ms

NS Lifetime∞

Indefinitely Stable Neutron Star Remnant?
(e.g. BDM+08; Ozel et al. 2010; Bucciantini et al. 2012; Zhang 13; Giacomazzo & Perna 13; Falcke & Rezzolla 13; Kiziltan 2013)• Requires: low total mass binary, stiff EOS*, and/or mass loss during merger*supported by recent discovery of 2M NS by Demorest et al. 2011

• Rotating near centrifugal break-up with spin period P ~ 1 ms
• Magnetic field amplified by rotational energy ⇒ “Magnetar” ?
(e.g. Thompson & Duncan 92; Price & Rosswog 2006; Zrake & MacFadyen 2013)

Giacomazzo & Perna 2013

Short GRBs with Extended Emission
 1/5 Swift Short Bursts have X-ray Tails
GRB 050709

 Rapid Variability ⇒ Ongoing Engine Activity
 Energy up to ~30 times Burst Itself!

Extended Emission

GRB080503
SEE/SGRB ~ 30

Perley, BDM et al. 2009

BATSE Examples (Norris & Bonnell 2006)

Magnetar Spin-Down Powered Extended Emission(BDM et al. 2008; Bucciantini, BDM et al. 2012; cf. Gao & Fan 2006 )Magnetar wind confined by merger ejecta

Theoretical Light Curves
vs. observed X-ray tails

Bucciantini et al. 2011

(magnetar outflow model from Metzger et al. 2011)

JetMergerEjecta

P0 = 1.5 ms,Bdip = 2×1015 G

MagnetarWind

Jet may continue to inject energy into forward shock or
produce lower level prompt emission(Zhang & Meszaros 2001; Dall’Osso et al. 2011; Rowlinson et al. 2013; Gompertz et al. 2013)

Millisecond Magnetar Wind Nebula
Metzger & Piro, submitted (see also Yu et al. 2013)

time for jet toescape envelope
Bromberg et al. 2011

jet power ∝ pulsar luminosity!

µ 2" 4
L j ~ Lsd = 3c

⇒ Jet ‘choked’ behind ejecta at late times

Millisecond Magnetar Wind Nebula
Metzger & Piro, submitted (see also Yu et al. 2013)

time for jet toescape envelope
Bromberg et al. 2011

jet power ∝ pulsar luminosity!

µ 2" 4
L j ~ Lsd = 3c

⇒ Jet ‘choked’ behind ejecta at late times
1.

2.

Evolution Model for Millisecond Pulsar Wind Nebulae(BDM, Vurm, Hascoet & Beloborodov 2013; BDM & Piro 2013)

Non-Thermal (UV / X-rays)
Source: cooling e+/- pairs (pulsar)
Sinks: PdV work, absorption by ejecta walls

Thermal Bath (Optical)
Source: re-emission of X-rays by ejecta walls
Sinks: PdV work, radiative diffusion
Fe1+Fe2+

Fe3+

Ejecta Ionization State- Balance photo-ionization with recombination inionized layer(s)- Sets ejecta albedo (thermalization efficiency)

Example (Mej=10-2 M; Bd =1015 G)

Optical [Solid], X-ray [Dashed] Light Curves

Example (Mej=10-2 M; Bd =1015 G)?

Optical [Solid], X-ray [Dashed] Light Curves

Example (Mej=10-2 M; Bd =1015 G)

Optical [Solid], X-ray [Dashed] Light Curves?

Peak Luminositye+/-$ pairs"#$ ejt peakτ! ejpeak,2 / 3
5/6& Bd ) ,2 / 3 & M ej ) & v ej )% 2.7( 15 + ( ,2+ ( +'10 G * ' 10 M! * ' c *!

τpairsLopt,peak " # $3 / 2 Lsd t

χ > 1 ⇒ X-rays lose most of their energy to P dV
work before reaching ejecta walls to be absorbed

X-ray Excesses in Kilonova Candidates
GRB 130603B

Fong et al. 2013

GRB 080503

Perley et al. 2009

See also Zhang 2013, Gao et al. 2013

(BDM & Bower 2013)• Rotational energy

eventually transferred to ISM⇒ bright radio emission (cf. Gao+13)• Observed 7 short GRBs with VLA
on timescales ~1-3 years after burst• NO DETECTIONS ⇒ rules out
stable NS remnant in 2 GRBs withknown high ISM densities• Upcoming radio surveys (e.g.
ASKAP) will strongly constrain
population of stable NS merger
remnants ⇒ indirectly probes EoS

Rest-Frame Time Since GRB (years)

Radio survey
constraints
10-4 yr-1 gal-1

Frail et al. 2012

• Additional JVLA observations now
much more constraining

1.4 GHz Luminosity (erg s-1)

Radio constraints on long-lived NS merger remnants

Timeline of Binary NS Mergers
1.

Chirp enters LIGO Bandpasst (minus) ~ mins

2.

Last Orbit, Plunge & Dynamical Ejectat ~ ms3.

BH Formation~ ms - ∞4.

Accretion of Remnant Disk, Jet Formation (GRB)~ 0.1-1 s

5.

He-Recombination + Disk Evaporation~ 0.3-3 s⇒ outflow Ye depends on NS collapse time

6. R-Process in Merger Ejecta~ few s7. Jet from Magnetar (X-rays)~ min (or longer)

8. Disk Wind Kilonova⇒ prompt BH formation Ye < 0.25 (NIR, L ~ 1041 erg s-1)
⇒ delayed BH formation Ye > 0.3 (Optical, L ~ 1042 erg s-1)
⇒ stable magnetar (Optical, L ~ 1044 erg s-1)

~ week~ day~ day9.

Tidal Tail Kilonova (IR)~ week10.

Ejecta ISM Interaction (Radio)~ years⇒ Much brighter if stable magnetar

Workshop: March 10 - April 17, 2014

Conference: March 24 - 28, 2014

• Equation of state of dense matter, including hyperon,kaon and quark degrees of freedom• Neutrino emission and cooling of compact stars• Constraints from EM observations• Gravitational wave sources• Models for Supernovae and for Gamma Ray Bursts• Magnetarsorganizers:
Fiorella Burgio
Allessandro Drago
Ian Jones
Brian Metzger
Pierre PizzocheroAnna Watts

Registration Deadline: December 15, 2013
http://indico.cern.ch/e/NS2014