Gamma Ray Bursts, Supernovae, and the Gamma Ray Bursts, Supernovae, and the Origin of Cosmic RaysOrigin of Cosmic Rays

Charles Dermer (Naval Research Laboratory)Erice

June, 2002

James Chiang (NASA/GSFC and UMBC) Markus Böttcher (Rice University)

Edison Liang (Rice University) Chris Fryer (Los Alamos National Laboratory)

Reinhard Schlickeiser (Bochum University) Mayer Humi (Worcester Polytechnic Institute)

Progress in the solution of one astronomical mystery – Gamma Ray Bursts – is leading to the solution of the mystery of Cosmic Ray Origin

OutlineOutline

GRBs

Cosmological Origin

Star-Forming Galaxies /Highly Beamed

Rare Type of Supernova

Cosmic Rays

Supernova Origin Hypothesis

High-Energy CosmicRays / Lack of ObservationalConfirmation

Fireball/Blast Wave Model

GRB statistics

Power Requirements

Acceleration Theory

Argument for the Supernova Origin of Cosmic Rays: PowerArgument for the Supernova Origin of Cosmic Rays: Power

• Local energy density of CR– uCR 1 eV cm-3 10-12 ergs cm-3

• Cosmic ray power requirements– LCR uCRVgal/tesc

51040 ergs s-1

• Galactic volume – Vgal (15 kpc)2200 pc 41066 cm3

• Cosmic ray escape time from galaxy – tesc c 10 gm-cm-2 / (mp 1 cm-3 c)

6106 yr– (information from 10Be used to determine mean density smaller and larger Vgal)

• Galactic SN luminosity: 1 SN/ 30 yrs ~1051 ergs in injection energy – LSN 1042 ergs/s

Knee

AnkleGeV/nucleon

Argument for the Supernova Origin of Cosmic Rays: Acceleration Argument for the Supernova Origin of Cosmic Rays: Acceleration

• Particle acceleration at astrophysical shocks

• Power-law particle energy spectrum with number index 2

• Maximum particle energy

• BISM 3 Gauss. What is R?

• Particle acceleration suppressed when

RZeBrFE

BqEBc

vqF

ISM

max

)(

eVn

m

G

BZE

MMmnMcmn

mR

ISM

oISM

opISMupsweptISM

oS S

3/116max

exp33/118

)()3

(10

1013

4,)(106.6

Emax near knee energy

Proton Larmor radius:

rL 3 pc /BG at E =3 1015 eV (knee)

Prediction to Confirm Supernova Origin of Cosmic Rays Prediction to Confirm Supernova Origin of Cosmic Rays

• o gamma-ray bump near 70 MeV, as seen in Solar flares

(Ginzburg and Syravotskii 1964; Hayakawa 1969)

2 XNp oISM

Evidence for nonthermal electron acceleration in SN 1006

• Unidentified EGRET sources are not firmly associated with SNRs and do not display 0 features; now appear more likely to be associated with pulsars

However…No Observational Evidence for However…No Observational Evidence for Hadronic CR Component in Galactic Supernova RemnantsHadronic CR Component in Galactic Supernova Remnants

pp 30 mb

100 MeV - TeV 100 MeV - TeV Rays not detected at expected levels Rays not detected at expected levels

12211

2

51

)4.3

()1.0

(107

4

/10

scmergskpc

dn

d

ncefficiencySNergs

ISMp

ISMppp

Cassopeia A; VLA Radio Image

Aharonian et al. 2001

Upper limits on TeV fluxes fromWhipple observations of SNRs(Buckley et al. 1997)

Cas A

Hunter et al. (1997)

Spectrum of Diffuse Galactic Spectrum of Diffuse Galactic –Ray Background Harder–Ray Background Harderthan Expected from Locally Observed Cosmic Raysthan Expected from Locally Observed Cosmic Rays

(calls into question power estimate)

• Neither nonrelativistic or relativistic first-order shock-Fermi mechanism is capable of accelerating particles to the ankle (~10 19 eV) of the cosmic ray spectrum

v0 = 0c is initial speed of supernova remnant shell

0 is its Lorentz factor

• Obtain higher maximum particle energies for supernova remnants with faster initial speeds• What are speeds of supernova ejecta?

Origin, Composition, and Spectrum of Cosmic Rays above Knee of Origin, Composition, and Spectrum of Cosmic Rays above Knee of thethe

Cosmic Ray Spectrum unexplainedCosmic Ray Spectrum unexplained

eVn

mZBE

ISM

oGI

3/103/20

16max, )(10

• Predict a cutoff above 1020 eV due to p + 0,+ interactions with Cosmic Microwave Background radiation (Greisen, Zatsepin, Kuzmin, or GZK effect)

• AGASA observations show no cutoff (HiRes observations disagree with AGASA; Hamburg ICRC 2001)

Mystery of the Ultra-High Energy Cosmic RaysMystery of the Ultra-High Energy Cosmic Rays

Observations show no cutoff

White Dwarf Detonation

Supernova Ia: 0 = v0/c 0.02-0.1

Core Collapse Supernova

Supernova II: 0 0.005-0.05

Supernova Ib: 0 0.03-0.1 (no H)

Supernova Ic: 0 0.05-0.5 (no H, He)

GRBs: 0 1, 0 100-1000

Different Types of Supernovae

Type I: no H lines in spectra, Type II: H lines

Burrows (2000)

GRB 990123GRB 990123

BATSEBATSE

Backgrounds:Diffuse X-ray backgroundInternal radiation backgrounds

BATSE triggering: 64, 256, 1024 ms> 0.5 ph cm-2 s-1 in 50-300 keV band

sensitivity 10-7 ergs cm-2 s-1

BATSE Evidence for Cosmological Origin of GRBsBATSE Evidence for Cosmological Origin of GRBs

N p-3/2

Implied geometry: We are at the center of a spherical, bounded distribution.

Most natural geometry is entire universe, with reduction of faint GRBs due to cosmological effects

GRB Peak Count Rate Distribution

• No evidence for anisotropy in GRB directions (Meegan et al. 1992)

• Peak count size distribution deviates from -3/2 size distribution

Directional Distribution

0 2 4 6 8

GRBs: Light Curves, Durations and Peak Energy GRBs: Light Curves, Durations and Peak Energy DistributionsDistributions

t (s)

Sample of Different GRB Light Curves

GRB Duration Distribution

Epk = Peak energy of F DistributionSpectraPeak Energy Distribution

Epk Epk

Kouveliotou et al. (1993)

Schaefer et al. (1998)

Mallozzi

et al.

(1997)

Beppo-SAXBeppo-SAX

Gamma Ray Burst Monitor: 60-600 keV; sensitivity 10-6 ergs cm-2 s-1 Wide Field X-ray Camera: 2-30 keV; sensitivity ~10-8 – 10-10 ergs cm-2 s-1

Narrow Field Instruments: 0.1-300 keV; sensitivity ~10-12 – 10-14 ergs cm-2 s-1

GRB 970228

X-ray Afterglow X-ray Afterglow observationsobservations

• Beppo-Sax X-ray discovery of fading X-ray afterglows: “all” long-duration GRBs have X-ray afterglows

• Power law decay ~t-, ~ 1.1 – 1.5

• X-ray lines and absorption edges: – Fluorescence Fe K lines

– Fe absorption feature in prompt phase

– Variable X-ray absorption (variations in NH)

Costa et al. (1999)

Large amounts of Iron in the vicinityof a GRB

Optical transient discovery Optical transient discovery imageimage

van Paradijs et al. (1997)

(see van Paradijs, Kouveliotou, and Wijers 2000 for review)

Optical spectrum Optical spectrum of GRB 970508of GRB 970508

•17+/- (1-2) GRBs with measured redshifts

Redshift and Apparent Isotropic Energy Redshift and Apparent Isotropic Energy DistributionDistribution

L = 4dL2(ergs cm-2 s-1)(1+z) t L

Rest mass energy of the Sun

GRB Host GRB Host GalaxiesGalaxies

• Nonthermal optical radiation: – Power-law (not thermal) emission

– Bluish host galaxies

– 1/3 dark bursts Dusty media Regions of active star formation

Radio scintillationRadio scintillation

• Nonthermal Radio Emission – ~ 25% of GRBs show delayed radio emission

– Scintillation effects at early times and at low frequencies

(Frail et al. 1997)

High-energy radiation from High-energy radiation from GRBsGRBs

Hurley et al. 1994

• 100 MeV radiation observed from 6 GRBs with EGRET onboard CGRO

• TeV radiation (Milagrito) Atkins et al. (2000) Nonthermal processes

Fireball/Blast wave model for Fireball/Blast wave model for GRBsGRBs

External MediumUnshocked shell

GRB source

Shocked shell

*

Cloud Forward Shock

Reverse Shock

0

Captured particle

Simple blastwave model

1. Spherical, uncollimated explosion2. Uniform surrounding medium3. Blast wave approximated as a

uniform thin shell 4. Particle acceleration at forward

shock only

Doppler factor:

Three frames of references:

Stationary frame dt*

Proper (comoving) frame dt’

Observer frame dt

Kinematics of relativistic Kinematics of relativistic systemssystems

cdxzdt

dtdtz

Pcdtcdtcdtdx

2

*

/)1(

)cos1(')1(

''

icrelativist

isticnonrelativ

xcmndtdE p

,

,2/

)(4'/'

22

22

223*

Blandford and McKee (1976)

x

1)]cos1([

nCBM

Relativistic blast wave shell closely follows photon shell

Energy swept into blast wave shell:

Initial blast wave momentum Po = oo , Blast wave momentum P = Deceleration radius

Deceleration time

Spherical Spherical blast-wave blast-wave evolutionevolution

in adiabatic in adiabatic regimeregime

2/3

30000 ][)]([

x

xkMxMMM su

sn

E

cP

xt

cmn

E

ncm

Ex

dd

p

d

3/28

300*

52

000

3/22

300*

52163/12

0*20

)(10

)(106.2)4

3(

3

0

)/(1)(

dxx

PxP

Dermer and Humi (2001)

Recover Sedov solution when P0 0

5/35/2

2/3

,

)(

tvtxvtx

xxv

Relativistic (>>1) behavior:

8/34/1

321

2/3

,

/

ttx

xdxdxct

x

GRBs are like supernovae with relativistic ejecta

Blast wave sweeps up both mass and energy

Elementary Elementary Blast Wave Blast Wave

TheoryTheory

• Nonthermal synchrotron radiation in shocked fluid– Joint normalization to power and number gives

• Magnetic field parametrized in terms of equipartition field

• Injection of power-law electrons downstream of forward shock

• Maximum injection energy: balancing losses and acceleration rate

• Cooling electron break: balance synchrotron loss time with adiabatic expansion time

)/(;))(1

2(min tdEdeE

m

m

p

pe ee

e

pe

BncmeB

pB )(48

2*

22

3/4

)(,)(3

2min

xnN

comovingNN

exte

eep

eee

)(/104 72 GB

tcmne

m

cm

ucttcxt

TpB

ec

ce

BTcadi

3*

12

16

3

)3

4(/

8/18/3min , tt c

Comoving Comoving NonthermNonthermal al Electron Electron SpectrumSpectrum

Transition from fast to slow cooling – if parameters ee, eB, p stay constant

21)1(

111

101

,)/()(

,)(

ep

ess

ooeee

es

es

oeee

NN

NN

minc

t

Fast cooling

s = 2

F

= c

= min

abs

4/3

Slow cooling

s = p

F

= c

= min

abs

4/3

1/2 (2-p)/2 (2-p)/2(3-p)/2

SSC

• p > 2• SSC important when eB << ee

• Uniform (not wind) geometry

)]1(2/[2 zcmeB eii

3 3

Numerical Simulation Model of GRB RadiationNumerical Simulation Model of GRB Radiation

• F spectra shown at observer times 10i seconds after GRB event• Primary radiation processes: nonthermal synchrotron and synchrotron self-Compton

Most common Most common prompt GRB light prompt GRB light

curvecurve

• Reproduces generic temporal behavior of smooth GRB profiles• Synchrotron-shock model reproduces time-averaged gamma-ray spectra of GRBs

Dermer, Böttcher, and Chiang (2000)

Short Timescale Variability due to inhomogeneities in Short Timescale Variability due to inhomogeneities in surrounding mediumsurrounding medium• Clouds with thick columns (> 4x1018 cm-2)

– Total cloud mass still small (<<10-4 Mo)• Cloud radii << R/ Dermer, and Mitman (2000)

Dirty and Clean Fireballs: Dirty and Clean Fireballs: strong GeV/TeV sourcesstrong GeV/TeV sources

Observed properties most sensitive to initial Lorentz factor of outflow (or baryon loading)

Severe instrumental selectionbiases against detecting fireballswith << 100 and >> 1000

Cosmological Statistics of GRBs in the External Shock Model

• Assume that distribution of GRB progenitors follows star formation history of universe Trigger on 1024 ms timescale using BATSE trigger efficiencies (Fishman et al. 1994)

• Broad distributions of baryon-loading 0 and directional energy releases are required. Assume power laws for these quantities.– 10-6 < E54< 1; N(E54) E54

-1.52; 0 < 260; N(0) 0 -0.25

Data: Meegan

et al. 1996Data: Mallozzi

et al. 1997

Data: Kouveliotou et al. 1993

Böttcher & Dermer (ApJ, 2000, 529, 635)

(Madau et al. 1998)

• Galaxy-averaged power associated with stars that collapse to form GRBs is at the level of ~1040 ergs s-1

• Inferred local power could be larger due to – Temporal stochastic variations– Enhancements due to preferential location

• Implied GRB progenitor rate in Milky Way from fits to statistics of BATSE data is ~1 GRB /(5000 yrs)

Gamma-Ray Bursts: Sources of Hadronic Cosmic Rays?Gamma-Ray Bursts: Sources of Hadronic Cosmic Rays?

Are Gamma-Ray Bursts Jetted?Are Gamma-Ray Bursts Jetted?

Beaming break when

8/1

52

8/33/83/152

8/3

)()(12

)/(/1

E

ntdays

n

Et

tt

CBMbr

CBMbr

dbro

Detailed multiwavelength afterglow modelingDetailed multiwavelength afterglow modeling

Analysis of 4 GRBs (Panaitescu and Kumar 2001): GRB 980703, GRB 990123, GRB 990510, GRB 991216

Beaming angle ~ 1o-4o : beaming factor = 13,000/ (o)2

Evidence for Evidence for constant energy constant energy

reservoir reservoir

)(4

1 2 isoEEtot ergsEGRB50105)

3(3

GRB event rate > 500 x observed rate

Frail et al.(2001)

Connection of GRBs to Star Forming Regions and SupernovaeConnection of GRBs to Star Forming Regions and Supernovae

• Blue excesses in GRB host galaxies

• GRB optical counterparts coincident with center or spiral arms of galaxy hosts

• X-ray afterglows with no optical counterparts (due to extinction)• Weak evidence for Fe K line in X-ray afterglow spectra

• Spatial and temporal coincidence of GRB 980425 with SN 1998bw (Type Ic)

• Reddened supernova emission in late time optical afterglow spectra• Energy release in constant energy reservoir is comparable to SN energy

Host galaxy of SN 1998bw

Galama et al.

Source ModelsSource Models• Hypernova/Collapsar Model

– Massive Star Collapse to Black Hole– Energy released at rotation axis– Two orders of magnitude more energy available;

no prediction of constant energy reservoir – Requires active central engine– Does not admit (?) two-step collapse– Available number of sources

• Coalescing Compact Objects– Binary neutron stars known in

Galaxy (Hulse-Taylor pulsar)– Coalescence by gravitational

radiation– Expect ~1 coalescence event

per Myr per MW Galaxy (too few given beaming fraction)

– Prompt collapse– Expected to be found in

elliptical/non star-forming galaxies

(Eichler et al. 1989; Janka, Ruffert et al.)

(Woosley et al.; Paczynski; Meszaros and Rees)

X-ray features and the Supranova X-ray features and the Supranova modelmodel

• Supranova model (Vietri and Stella 1999)– Two-step collapse to black hole– Super-Chandresekhar mass neutron star stabilized against prompt

collapse by rotation– Supernova shell of enriched material – In dusty, star-forming regions– Standard energy reservoir– Prompt collapse following long quiescenceSupranova model more easily explains Iron absorption and fluorescence line observations

Rate and Power of GRBs into Millky-Way--Type (L*) Rate and Power of GRBs into Millky-Way--Type (L*) GalaxiesGalaxies

• BATSE observations imply ~ 1 GRB/day over the full sky

• Beaming factor increases that rate by factor ~500

• Volume of the universe ~ 4(4000 Mpc)3 /3

• Density of L* galaxies ~ 1/(200-500 Mpc3)

)3000/(105.3

)3

()6/1

(

10003651

)4000(3

4*/500

343

33

3

yrsfyr

fKSFR

KSFRfyrdayMpc

LMpc

FT

FT

Rate per L* galaxy

Time-averagedpower per L* galaxy

3/1;)3

)(6/1

(102

1032600

105.1)

3()

6/1(

140

7

51

sergs

KSFR

yrs

ergsKSFR

FT

FT

KFT correction factor for clean and dirty fireballs

Rates of various types of SNeRates of various types of SNe

~0.05Milky-Way type:

amultiply by factor of ~2 to get the SN rate per century in the Milky Way

Particle Acceleration at Astrophysical ShocksParticle Acceleration at Astrophysical Shocks

Combined 1st and 2nd order Fermi acceleration

2nd order Fermi acceleration: stochastic energy gains with Alfven turbulence, as in impulsive Solar flares

)3/5(),2/3()2/(1]9/2/32[

3/10

6/12/120max,

3/103/20

16max,

30

20

)(108

)(10

vvvfoBevK

oextBvII

ext

oGI

eVmfneZKE

eVn

mZBE

Fermi processes in relativistic flows formed by stellar collapse (either one- or two-step) events power the cosmic rays from the knee to ultra-high energies

Maximum Particle Acceleration at Maximum Particle Acceleration at Nonrelativistic and Relativistic ShocksNonrelativistic and Relativistic Shocks

• Typical fluence and rate of BATSE GRBs:– F 10-6 ergs cm-2 ; NGRB 1/day

• If weakest GRBs at z ~ 1, then d 1028 cm – E 4d2 F 1051 ergs; EGRB 1052 ergs

• UHECRs lose energy due to photomeson processes with CMB– p + p + 0 , n + – GZK Radius x1/2 (1020 eV) 140 Mpc

• Energy density within GZK Radius:– uUHECR GRB (x1/2 /c) EGRB (140 Mpc/c) 510-22 ergs/cm3

UHECRs from GRBsUHECRs from GRBsWaxman (1995); Vietri (1995)

Stanev et al. (2000)

.

day(4/3)(1028cm)3

____________________

Synchrotron and Compton Neutron-Decay HalosSynchrotron and Compton Neutron-Decay Halos

• Neutrons formed through photomeson processes during cosmic ray acceleration escape from blast wave n p + e- + e

• Decay of neutrons occurs at n

– Produce nonthermal synchrotron radiation, depending on strength of halo magnetic field– Produce nonthermal rays from Compton scattering of CMB

• rays materialize through e+e-

• form extended pair and gamma-ray halo

• Relative strengths of synchrotron and Compton halos give strength of galactic halo magnetic field

• If GRBs signal birth event of a black hole, then > 2106 black holes with masses > 1-30 Mo are formed during the age of the Galaxy

• Gravitational deflection will increase their scale heights• Isolated accreting black holes that accrete from ISM could be cause of

unidentified EGRET -ray sources (Dermer 1997, 2000; Armitage and Natarjan 1999)

Black Holes from GRBsBlack Holes from GRBs

Low and mid-latitude unidentified -ray sources accrete from molecular clouds and dilute ISM, respectively.

Credit: R. C. Hartman and EGRET team

ConclusionsConclusions

• SN origin-hypothesis for cosmic rays meets with serious difficulties– Lack of confirmation of gamma-ray predictions– Theoretical difficulties to accelerate particles above the knee of the cosmic ray spectrum– Does not explain ultra-high energy cosmic rays

• GRBs are now thought to be rare type of SN– Forming relativistic, highly collimated ejecta– Possibly formed in two-step collapse prccess to black hole

• Time and space-averaged power of relativistic flows into Milky Way from GRB events that accompany supernovae is ~1040 ergs s-1

• GRB events accompanying SNe occur at a rate of 1 per 2-4 millenia throughout the Milky Way • Relativistic flows accelerate particles to > 1020 eV (through 2nd order processes)

– Can accelerate cosmic rays at energies between knee and ankle– Look for beamed signatures in galactic SNe; hadronic signatures in 1 out of ~20 SNRs– GRBs potentially power the UHECRs

• Thus the hypothesis that CRs originate from particle acceleration in SNRs powered by SNe in the galaxy, is suggested to be replaced with the hypothesis that

Cosmic Rays originate from the stars that produce the subclass of SNe whose core collapses a second time to a black hole which powers relativistic flows and GRBs