the structure and dynamics of relativistic jets
TRANSCRIPT
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The Structure and Dynamics of Relativistic Jets
Image credit: AURA / Lynette Cook
Tanmoy Laskar Jansky Fellow
NRAO / UC Berkeley
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Relativistic jets in Astrophysics
NASA and The Hubble Heritage Team (STScI/AURA)
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Relativistic jets in Astrophysics
AGN Mergers GRBs TDFs
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Relativistic Jets in Gamma-ray bursts
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Gamma-ray Bursts: two classes
LongShort
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Long-duration Gamma-ray Bursts
• Located in star forming regions of galaxies
• Associated with supernovae • Most energetic explosions in the
universe: Eγ,iso ~ 1054 ergVisible to high redshifts (z ~ 9, and beyond!)
• Short durations (minutes) → Relativistic expansion
• Powered by compact central engine
Catastrophic death of a massive star
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The Fireball model
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GRBs: The Radiation Mechanism
Sari, Piran & Narayan (1998)
Energy, EK Density, n Shock physics (𝜺e, 𝜺B)
Flux
den
sity
Frequency
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The Structure & Dynamics of Relativistic Jets
• What is the central engine (NS? BH?)
• What is the energy extraction mechanism?
• What is the jet launching mechanism?
• How are the jets collimated?
Measure fundamental quantities: Lorentz factor, energy, magnetization, collimation
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The Reverse Shock
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The Reverse Shock
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Then Reverse ShockIf baryonic ejecta,
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GRBs: Relativistic Transients
Radi
o
Opt
ical
X-ra
ys
Mill
imet
er
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Multi-wavelength follow-up
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The GRB Afterglow Multi-wavelength Modeling Application
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Multi-wavelength modelling
• Full broadband spectral evolution • RS + FS • Jet breaks (radio to X-rays) • Non-relativistic transition (radio) • Inverse Compton cooling (X-rays) • Effects of dust (optical) • IGM absorption (optical) • Interstellar scintillation (radio)
GAMMA
+ Robust statistical framework
Intri
nsic
Extri
nsic
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The hunt for reverse shocks
⌫m,RS =⌫m,FS
�2
⌫c,RS = ⌫c,FS
F⌫,m,RS = �F⌫,m,FS
The Reverse shock
Optical
Radio
GRB 990123
Radi
owav
e
Opt
ical
X-ra
ys
Mill
imet
erw
ave
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980703
980329
Chandra & Frail (2012)
Radio Observations of GRBs
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A Reverse shock in GRB 130427A
Radi
o
Opt
ical
X-ra
ys
Mill
imet
er
TL+13, ApJ, 776, 119
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RS FSFS
RS
X-ray
Optical
Radio
RS FSInfra-red
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A Reverse shock in GRB 130427A
RS and FS parameters independently derived, yet consistent: imply Γ~ 130
⌫m,RS =⌫m,FS
�2
⌫c,RS = ⌫c,FS
F⌫,m,RS = �F⌫,m,FS
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A Reverse shock in GRB 160509AΔt = 1.1d
Radi
o
Opt
ical
X-ra
ys
Mill
imet
er
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A Reverse Shock in
GRB 160509A
TL+16, ApJ, 833, 88
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A Reverse shock in GRB 160509A
• Γ~ 330
• Ejecta kinetic energy, EK ~ 4 x 1050 erg
• Low circumburst density, n ~ 10-3 cm-3
⌫m,RS =⌫m,FS
�2
⌫c,RS = ⌫c,FS
F⌫,m,RS = �F⌫,m,FS
TL+16, ApJ, 833, 88
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A Reverse Shock in GRB 161219B The First ALMA GRB Light Curve!
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X-ra
yU
VO
ptic
alin
frare
dRa
dio
TL+18, submitted
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Reverse Shocks require low circumburst density
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The Structure and Dynamics of Relativistic Jets