Gamma-Ray Bursts: 2. Long GRBs Brian Metzger, Columbia University - PowerPoint PPT Presentation

Gamma-Ray Bursts: 2. Long GRBs Brian Metzger, Columbia University

Gamma-Ray Burst Durations long short Duration BATSE Bursts (from Nakar 2007)

GRB 030329 and the Supernova Connection Exploding “Wolf-Rayet” Star radius R~10 11 cm (3 light-seconds).

GRB 030329 and the Supernova Connection ⇒ Long GRBs come from the deaths of massive Stars Exploding “Wolf-Rayet” Star radius R~10 11 cm Gamma-Ray Burst Galaxies (3 light-seconds). (courtesy A. Fruchter)

The ‘Collapsar’ Model (Woosley 1993) “GRBs are powered by accretion onto a new formed black hole”

Bl Black Ho Hole Model (Woosley 93; MacFadyen & Woosley 1999) Zhang, Woosley & Heger 2004 MacFadyen & Woosley 1999 % ( E ~ " j M # c 2 ~ 10 51 ergs " j % ( * M # M ! ' * • Energy Energy - Accretion Power ' 10 $ 3 & ) & ) 1/ 2 % ( • Duration Duration - Collapse Time of Star t ff ~ 3 " 32 G # $ ' * ~ 100 s & )

L j < 10 " 3 ˙ c 2 M Generally inefficient:

MHD Powered Jets (e.g. Blandford & Znajek 1978) Rezzolla et al. 2010 How is magnetic field generated?

credit: Stan Woosley

Mi Millisecond Ma Magnetar Mo Model (e.g. Usov 1992; Metzger et al. 2011) Bucciantini, Metzger et al. 2011 Ω Surrounding Star Magnetar Wind $ 2 E rot ~ 12 I " 2 ~ 3 # 10 52 ergs P 1 ms ( ) • Energy Energy - Rotation 2 + 4 % ( L sd = µ 2 " 4 B dip % ( P # 6 $ 10 49 erg s -1 • Luminosity - Luminosity - Dipole Radiation ' * ' * c 3 10 15 G & 1 ms ) & ) -2 2 $ ' B dip $ ' " sd = E rot P • Duration Duration - Spin-Down Time 0 # 10 min & ) & ) 10 15 G L sd 1 ms % ( % (

Magnetars: Super-Magnetized Neutron Stars  Surface Magnetic Field 10 14 -10 15 G (would erase your credit card at distance of Sun).  Observationally classified as “soft gamma- ray repeaters” and “anomalous X-ray pulsars” SGR1806-20 Giant γ -Ray  “Giant Flares” every Flare in December 2004 ~10-100 years.  12 in Milky Way  Age: 10 3 -10 4 yrs  rotation period P ~ secs

What Produces Magnetar Fields? ΔΩ All neutron stars form as hot, differentially-rotating ‘proto-neutron stars’ Dessart et al. 2006 V c rotational * 2 $ ' E rot = 1 P 2 I " 2 ~ 3 # 10 52 ergs & ) energy: % 1 ms ( 2 - 2 " E rot = B 2 ' * ' * 8 # $ 4 # 3 % B eq ~ 10 17 "& P 3 R ns G ) , ) , ( & /2 + ( 1 ms + Field amplification: • Shear instabilities (talk by Zrake) Magnetic activity of late type stars • Magneto-rotational instability Pizzolato et al. 2003 • α - Ω dynamo (Thompson & Duncan 1993) " ~ 4 # R 2 $ V c 3 , l P ~ 0.1 R NS L 1/ 3 , 1/ 3 & ) 5/ 3 & ) & ) l P + R NS & ) L $ % c ~ l P V c ~ 1 ms " ( + ( ( + ( + 10 14 g cm -3 10 52 erg s -1 0.1 R NS ' 12 km * ' * ' * ' * Ro ~ 1 for P ~ 1 ms Log ( Ro " P # c ) Rossby Number

Core Collapse with Magnetic Fields & Rotation (e.g. LeBlanc & Wilson 1970) “Failed Collapsar” Neutron Star Mass ˙ M OUT ˙ M IN Time

Neutrino Driven Wind Neutrinos heat proto-NS atmosphere ( e.g. ν e + n ⇒ p + e - ) ⇒ drives wind behind outgoing supernova shock (e.g. Qian & Woosley 96) Burrows, Hayes, & Fryxell 1995 5/ 3 10/ 3 $ ' $ ' L * # ⇒ crucial to baryon loading ˙ M ~ 10 " 4 M ! s " 1 # & ) & ) 10 52 erg s -1 % 10 MeV ( % (

Neutrino Driven Wind Neutrinos heat proto-NS atmosphere ( e.g. ν e + n ⇒ p + e - ) ⇒ drives wind behind outgoing supernova shock (e.g. Qian & Woosley 96) Before SN Shock Launch After Shock Launch Neutrino-Heated Wind Burrows, Hayes, & Fryxell 1995 5/ 3 10/ 3 $ ' $ ' L * # ⇒ crucial to baryon loading ˙ M ~ 10 " 4 M ! s " 1 # & ) & ) 10 52 erg s -1 % 10 MeV ( % (

Effects of Strong Magnetic Fields • Microphysics (EOS, ν Heating & Cooling) “Helmet - Streamer” – Important for B ≥ 10 16 G (Duan & Qian 2005) Ω

Effects of Strong Magnetic Fields • Microphysics (EOS, ν Heating & Cooling) “Helmet - Streamer” – Important for B ≥ 10 16 G (Duan & Qian 2005) • Magneto-Centrifugal Slinging (Weber & Davis 1967; Thompson, Chang & Quataert 2004) Ω Outflow Co-Rotates with Neutron Star when B 2 8 " > 12 # v r 2 R A R heat ⇒ Magneto-Centrifugal Acceleration (“Beads on a Wire”) Top View

Regimes of Magnetized PNS Winds (B = 3 × 10 14 G) Metzger, Thompson, Quataert 2007 Neutrino Luminosity (10 51 erg s -1 ) Thermally-Driven Magnetically-Driven, Mildly Relativistic Magnetically-Driven, Ultra-Relativistic Rotation Period (ms)

Regimes of Magnetized PNS Winds (B = 3 × 10 14 G) Metzger, Thompson, Quataert 2007 Thermally-Driven Neutrino Luminosity (10 51 erg s -1 ) t ~ 1 s Magnetically-Driven, Mildly Relativistic Magnetically-Driven, Ultra-Relativistic t ~ 100 s Rotation Period (ms)

Regimes of Magnetized PNS Winds (B = 3 × 10 14 G) Metzger, Thompson, Quataert 2007 Thermally-Driven Neutrino Luminosity (10 51 erg s -1 ) t ~ 1 s Magnetically-Driven, Mildly Relativistic Magnetically-Driven, Ultra-Relativistic t ~ 100 s Rotation Period (ms)

Evolution of Proto-Magnetar Outflows (BDM et al. 2007, 2011) Neutrino Cooling Evolution NS Cooling Luminosity Roberts 2012 3D Magnetosphere Geometry (e.g. Bucciantini et al. 2006; Spitkovsky 2006) Wind Power ˙ (t), Mass Loss Rate ˙ E M (t), Calculate: " 'Magnetization' # (t) ~ ˙ E ˙ c 2 = $ max (t) M In terms of Initial rotation period P 0 , dipole field B dip & obliquity θ dip

Example Solution magnetization " 0 ~ # max spin - down power ˙ iso /10 50 erg s -1 E ˙ B 2 % 4 E " 0 ~ # c 2 $ max = increases as magnetar cools ˙ 5/3 T 10/3 M L &

Collimation via Stellar Confinement Multi-Wavelength Crab Nebula PWN OPTICAL RADIO X-RAYS SNR PULSAR 3C58 (Chandra)

Collimation via Stellar Confinement Multi-Wavelength Crab Nebula PWN OPTICAL RADIO X-RAYS Ω SNR PULSAR Ω Supernova remnant elongated by anisotropic magnetic stresses in pulsar nebula? (Begelman & Li 1992) 3C58 (Chandra)

Outgoing SN shock V SN ~ 0.1 c

Outgoing SN shock V SN ~ 0.1 c Fast Magnetar Wind V w ~ c

Outgoing SN shock V SN ~ 0.1 c

Outgoing SN shock V SN ~ 0.1 c

Jet Formation via Stellar Confinement (Bucciantini et al. 2007, 08, 09; cf. Uzdensky & MacFadyen 07; Komissarov & Barkov 08) Zoom Out Kink Instability Jet power & mass-loading 2D 3D Porth, Komissarov, & Keppens 13 match (on average) outflow from central magnetar

Non-Relativistic ( σ 0 < 1) Relativistic ( σ 0 > 1) Jet Break-Out " 0 ˙ iso /10 50 erg s -1 E Outflow becomes relativistic at t ~ 2 seconds; Jet breaks out of star at t bo ~ R  / β c ~ 10 seconds

Non-Relativistic ( σ 0 < 1) Relativistic ( σ 0 > 1) Jet Break-Out Jet Break-Out ← GRB → " 0 ˙ iso /10 50 erg s -1 E Outflow becomes relativistic at t ~ 2 seconds; Jet breaks out of star at t bo ~ R  / β c ~ 10 seconds

GRB Em GRB Emissi ssion on - What hat, Where, here, How? How? Relativistic Outflow ( Γ >> 1) Photospheric IC ~ 10 7 cm Central Engine GRB / Flaring Afterglow 1. What is jet’s composition? (kinetic or magnetic?) 2. Where is dissipation occurring? (photosphere? deceleration radius?) 3. How is radiation generated? (synchrotron, IC, hadronic?)

Time-Averaged Light Curve Metzger et al. 2011 ˙ E jet Optically-Thick Optically-Thin Jet Break-Out Photospheric Dissipation (IC)

Time-Averaged Light Curve Metzger et al. 2011 ˙ E jet Optically-Thick Optically-Thin Jet Break-Out Spectral Snapshots E F E (10 50 erg s -1 ) IC Tail BB Synch t ~ 15 s t ~ 30 s Hot Electrons ⇒ IC Scattering ( γ -rays) and Synchrotron (optical) E (keV)

End of the GRB = Neutrino Transparency? Ultra High- σ Outflows baryons e - /e + pairs ⇒ - Acceleration is Inefficient ← GRB → (e.g. Tchekhovskoy et al. 2009) - Internal Shocks are Weak " 0 (e.g. Kennel & Coroniti 1984) - Reconnection is Slow (e.g. Drenkahn & Spruit 2002) ˙ iso /10 50 erg s -1 E T GRB ~ T ν thin ~ 20 - 100 s

End of the GRB = Neutrino Transparency? Ultra High- σ Outflows baryons e - /e + pairs ⇒ - Acceleration is Inefficient ← GRB → (e.g. Tchekhovskoy et al. 2009) - Internal Shocks are Weak " 0 (e.g. Kennel & Coroniti 1984) - Reconnection is Slow (e.g. Drenkahn & Spruit 2002) ˙ iso /10 50 erg s -1 E Steep Decline T GRB ~ T ν thin ~ 20 - 100 s Low plateau efficiency consistent with Lu & Zhang 2014

← GRB → Late-Time Spin-Down τ SD ˙ iso /10 50 erg s -1 E e.g. Zhang & Meszaros 2001; Troja et al. 2007; Yu et al. 2009; Lyons et al. 2010

← GRB → X-ray Afterglow Late-Time Spin-Down Willingale et al. 2007 `Plateau’ τ SD ˙ iso /10 50 erg s -1 E e.g. Zhang & Meszaros 2001; Troja et al. 2007; Time after trigger (s) Yu et al. 2009; Lyons et al. 2010; Rowlinson et al. 2010, 2013; Gompertz et al. 2013

A Diversity of Magnetar Birth Classical GRB E γ ~10 50-52 ergs, τ jet < 1, Γ ~ 10 2 -10 3 B dip (G) P 0 (ms)