Multi-Messenger
GRB
Astrophysics
Michael Stamatikos
Center for Cosmology and AstroParticle
Physics (CCAPP) Fellow
The Ohio State University (OSU)
Michael.Stamatikos-1@nasa.gov
GSFC
The Inaugural CCAPP Symposium 2009
The Ohio State University
Department of Physics
October 12, 2009
Overview
I. GRB Electromagnetic Emission
A. Prompt
B. Afterglow
II. GRB Satellite Missions
A. Swift (BAT, XRT & UVOT)
B. Fermi (LAT & GBM)
C. Correlative observations of GRBs
III. Neutrino Astronomy
A. Fireball phenomenology & GRB Neutrinos
B. Discrete Neutrino flux
C. IceCube/ANTARES/NESTOR/KM3NET
IV. Summary & Future Outlook
A. Decade of science synergy
Gamma-Ray Bursts (GRBs): Prompt Emission
• GRBs are unique, varying from burst to burst and class to class (short, long, X-ray rich, non-triggered).
• Super-Eddington luminosities imply relativistic expansion.
• Millisecond temporal
variability implies compact
objects R ≤ 2G2cDt.
• Compactness problem
resolved via ~100 ≤ GBulk ≤
~1000, ensuring transparent
optical depth to observed gray photons, i.e. tgg ≤ 1.
AMANDA-II
IceCube
ANTARES /NESTOR
KM3NET
Number of Bursts
Briggs et al., ApJ 459: 40 (1996)
T90 (seconds) ≡ Time
required to accumulate
from 5% to 95% of total
counts in 50-350 keV band.
Durations
span 6 orders
of magnitude!
dng
d g
for  g   gb
for  g   gb
 Spectral number density
 ,   Spectral indices
Eo   gb  Break energy
“Short”
GRBs
~0.02 s
Kouveliotou et al., ApJ 413: 101 (1993)
T90 (seconds)
“Long”
GRBs
~1301 s
Number of Bursts
Number of Bursts
BATSE GRBs
 g dng  g
 
d g
 g
“Short”
GRBs
are
“hard”
“Long”
GRBs
are
“soft”
GRBs: Multi-Wavelength EM Afterglows
Spectroscopically
observed Doppler
redshifts from optical
transient (OT)
afterglows.
Isotropic Emission
Beamed Emission
Isotropic Emission: ~ 1 GRB/Day → RGRBiso ~ 0.5 GRB/(Gpc3·yr).
Beamed (Jet) Emission: Corrections → RGRBiso·(4/Ωb) sr and
Egiso· (Ωb/4) sr. Where: Wb ≡ Beaming solid angle (sr).
f b  1  cos  jet  Beaming fraction
1
 jet  1 GBulk
GBulk 
1 v2 / c2
“Swifts fly expertly on their first
try. Regardless of their
introduction to flight, all young
are adept at it soon after they
take their initial leap.”
– National Geographic Society
Boeing Delta II expendable launch vehicle
ignition blasted NASA's Swift spacecraft
from Complex 17A, Cape Canaveral Air
Force Station, FL on Nov. 20 at
12:16:00.611 p.m. EST in 2004.
The Swift MIDEX Mission
The Swift MIDEX Mission
•
Burst Alert Telescope (BAT) 15-150 keV
– Coded array of 32,768 CdZnTe detectors.
– Sensitivity~ 10-8 ergs/cm2/sec
– Detects ~100 GRBs per year
– Energy resolution ~7 keV
– PSF = 17’, 1-4 arcmin positions
•
X-Ray Telescope (XRT) 0.2-10 keV
– Arcsec positions 23.6”x 23.6” FOV
– Sensitivity ~2x10-14 ergs/cm2/s
– 1 mcrab in 104 sec
– CCD spectroscopy
•
BAT
UVOT
(UVOT) UV/Optical Telescope
– Sub-arcsec imaging, 17”x17” FOV
– Grism spectroscopy
– 24th mag sensitivity (1000 sec)
– 170 nm - 600 nm, 6 colors
– Sensitivity~ B=24 in white light in 1000 s
XRT
Autonomous re-pointing, DQ = 50 < ~75 s, Orbit of 600 km x 21 inclination.
XRT Image < 90 s
UVOT Image
GRB Triggers BAT
T < 10 sec
sR < ~4 arcmin
T< 300 sec
BAT Error Circle
Temporal Decay of Afterglows: XRT & UVOT GRB 050525A
Fluxes decrease
by orders of
magnitude in
first hours!
UVOT
XRT
~400 Swift GRBs
95% with XRT @ T < 200 ks
~60% with optical (UVOT + ground)
~10% Short GRBs
• Afterglow Curves, Breaks, Flares, etc.
• SGRB Redshift within elliptical galaxy
• SGRB with extended soft emission
• Over 133 Swift GRBs have redshifts.
• GRB 090423 z ~ 8.0! (GCN 9215), i.e.
~85 Gpc or ~ 13 Gyr look back time.
Over ¾ of all GRB x-ray afterglows and
redshift are based upon Swift bursts!
Number
Gehrels et al., New Journal of Physics 9:37 (2007)
0.001
< z > = 2.3
0.01
0.1
Redshift
1
10
Fermi (LAT & GBM)
• Large Area Telescope (LAT)
- < 20 MeV to > 300 GeV
- Field of View (FOV) ~ 2.5 sr
• GLAST Burst Monitor (GBM)
- 8 keV – 30 MeV
• 12 Sodium Iodide (NaI)
Scintillation Detectors
– Energy Range:
• 8 keV – 1 MeV
– Wide FOV (~8 sr)
– Onboard Burst Trigger
• 2 Bismuth Germanate (BGO)
Scintillation detectors
– Energy Range:
• 0.15 – 30 MeV
– Provides important overlap
with LAT energy range.
Large Area Telescope
(LAT)
GLAST Burst Monitor
(GBM)
Correlative Observations: Mutual Science Benefit!
Comparison of Effective Areas
BATSE Epeak Distribution
12 NaI (8 keV to 1 MeV)
2 BGO (0.15 to 30 MeV)
LAT (20 MeV to >300 GeV)
Stamatikos arXiv:0904.2755
•
•
•
•
•
Y. Kaneko et al 2006, ApJS 166, 298
BAT increases GBM’s ~20-100 keV effective area by a factor of ~ 3.
Most GRBs have Epeak above BAT energy range. BAT-GBM GRBs↑ Epeaks.
BAT localization precision ~2-3 orders of magnitude better, ↑ follow-up (z).
Test validity of Epeak-Eiso redshift relationships (~35% Swift GRBs have z).
Broad-band spectral/temporal evolution ~ 6 energy decades (keV-GeV) for BATGBM, and ~11 energy decades for UVOT/XRT/BAT/GBM/LAT!! Has been realized
in GRB 090510: LAT/GBM (GCN 9334/9336) and BAT/XRT/UVOT (GCN 9331).
BAT-GBM Joint Spectral Fit of GRB 080810
Left plate: Swift-BAT light curve for GRB 080810 with T0 = 13:10:12.3 UTC. Blue
line indicates Swift slew-time. Red and green lines indicate 1st and 2nd joint fit
interval, respectively. Center plate: Joint Swift-BAT/Fermi-GBM energy spectral
fit for 1st interval, with fit parameters of α ~ 0.94 (+0.13, -0.15) and Epeak ~ 674
(+493, -237) keV (χ2/dof~1.33). Right plate: Joint fit for 2nd interval, resulting in fit
parameters of α ~ 1.15 (+0.09, -0.10) and Epeak ~ 406 (+189, -106) keV (χ2/dof~1.15).
Both intervals were best fit via a Comptonized model. Although consistent within
their error bars, the 2nd (brighter) interval provides a better Epeak constraint .
BAT-GBM Inter-calibration has ~50 common GRBs. Joint analysis is in preparation.
The Fireball Phenomenology: GRB-n Connection
GRB Prompt Emission
(Temporal) Light Curve
Electron
---
Low-Energy
Photon
g-ray
Electron
g-ray
Synchrotron Radiation
Self-Compton Scattering
Prompt g-ray emission of GRB is due to non-thermal processes such as
electron synchrotron radiation or self-Compton scattering.
Counts/sec
Magnetic Field
• Shock variability is a
unique “finger-print”
reflected in the
complexity of the GRB
time profile.
• Implies compact object.
Time (seconds)
External Shocks
Multi-wavelength Afterglows Span EM Spectrum
Internal Shocks
g-ray
Optical
X-ray
Radio
ep+
E  1051 – 1054 ergs
Prompt GRB
Emission
R < 108 cm
R  1014 cm
T  3 x 103 seconds
Afterglow
Spatial & temporal
coincidence with
prompt GRB
emission
R  1018 cm
T  3 x 1016 seconds
pγ
Ecm
 pγ center of mass energy & ETh
 Δ  threshold energy.
Δ
pg
If Ecm
 EDTh  p   g  D  n    n     n   e n e n 
Photomeson interactions involving relativistically (G 300) shock-accelerated
protons (Ep  1016 eV) and synchrotron gamma-ray photons (Eg  250 keV) in
the fireball wind yield high-energy muonic neutrinos (En  1014 – 1015 eV).
Optical Afterglow
Radio Afterglow
Spectral Fit Parameters
Ag, , , gb, gP
Prompt GRB Photon
Energy Spectrum –
Characterized by the
“Band Function”
Fireball Phenomenology: GRBs & n’s
• Fireball Phenomenology + Relativistic Hadronic Acceleration  Neutrinos.
n (eV)
Arrival Astrophysical Mechanism/Comments
107
Before
Progenitor Collapse/Merger
109 – 1010
Before
Baryonic (n, p) Longitudinal decoupling
1012 - ≤ 1014 Before
“Precursor” (pp/pg)
1014 – 1015
During
Prompt (Photomeson/internal shocks)
1017-1018
After
Afterglow (Photomeson/External shocks)
TeV-PeV muon neutrinos  spatio-temporal coincidence
“Background free” search
Razzaque, Meszaros & Waxman PRD 69 023001 (2004)
Stamatikos, M. et al., AIP Conference Proceedings 727, 146-149 (2004)
• “Smoking gun” signature of hadronic acceleration  cosmic rays
Waxman, E. Physical Review Letters 75, 386-389 (1995)
Stamatikos et al. astro-ph/0510336
• Assuming GRBs were CR accelerators  Diffuse flux prediction.
Waxman & Bahcall, Phys. Rev. D 59 023002
• AMANDA 1 PeV Diffuse Flux Upper Limits:
Achterberg et al., ApJ 664: 397 (2007)
Achterberg et al., ApJ 674: 357 (2008)
Motivation for Discrete Approach
• Diffuse flux methodology  All GRBs described by same energy spectrum
• Based upon average values for observables  contradicts observations.
• Distributions:
1. Span orders of magnitude,
5 orders of magnitude
2. Differ from burst to burst
3. Class to class, and are
4. Effected by selection effects.
• Fluctuations enhance neutrino
production, e.g. GRB 941017.
Few GRBs
produce
detectable
signal
Halzen & Hooper ApJ 527, L93-L96 (1999)
• EM variance  neutrino variance.
Alverez-Muniz, Halzen & Hooper Phys. Rev. D 62, (2000)
• GRB030329  Case study.
Stamatikos et al. astro-ph/0510336
Guetta et al., Astroparticle Physics 20 (2004) 429-455
Parameterization of Muon Neutrino Spectrum
  1

 n  
 b 

n   nb



 n 
 1




n

nb  n    b
n2 n   An     b 
 n 

    1     2
n    b
 n    n  
 nb    b 

Fg f
An  
 Normalizat ion
8 e ln 10T90




f  0.2 

Lg ,52

G t
4
b
2.5 v, 2 g , MeV

1  z 
1
max
g , 52 v,2 g , MeV
G ~ 276 L
t













 Proton effeciency
1  z 
1
6
Neutrino Flux Models
 Bulk Lorentz Boost Factor
 7 105 G22.5 
n  
 GeV  Neutrino break energy
2
b



1

z

g , MeV 

b
Model 1: Discrete Isotropic
Model 2: Discrete Jet
Model 3: Average Isotropic
Neutrino spectrum is expected
to trace the photon spectrum.
n    p   g1
 108 12 12

1
b
  
e B Lg ,52  2 G24.5 t v,2  GeV  Synchrotro n break energy
 1  z 

Stamatikos et al. astro-ph/0510336
Lg ,52 
Lg
52
10 ergs s
G
G2.5  2.5
10
t
t v,2  v2
10 s
 gb, MeV 
 gmax
, MeV 
 gb
1 MeV
g
100 MeV
Guetta et al., Astroparticle Physics 20, 429-455 (2004)
Conclusions
 Science Synergy: Swift-Fermi
affords spectral & temporal
evolution analysis over an
unprecedented 11 energy decades
(UVOTLAT)!
 Expect ~1-3 BAT-GBM GRBs/month (~3217/year).
 Can constrain/determine Epeak for all coincident bursts, use
redshift to determine burst luminosity and test empirical
redshift relations.
 Facilitate multi-messenger searches, e.g. neutrino astronomy
via IceCube/ANTARES/NESTOR and KM3NET. (See
Stamatikos et al 2009, Astro2010 Decadal Whitepaper.)