Gamma-Ray Bursts: The Biggest Explosions Since the Big Bang

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Gamma-Ray Bursts The Biggest Explosions Since
the Big Bang

• Kris Stanek
• The Ohio State University

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Outline

• Brief history
• Up close and personal with GRBs
• GRBs in Swift era
• Future directions

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Why do we care
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Killer GRBs!
The death of life on Earth?
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Brief History

• 1973 Discovery paper (Vela)
• 1992 BATSE showed that GRBs are isotropic on the
  sky, but with fewer faint GRBs
• 1995 Paczynski-Lamb debate
• 1997 Beppo-SAX finds first X-ray afterglows with
  accurate (few arcmin) localizations this leads
  to discovery of optical (GRB 970228) and radio
  (GRB 970508) afterglows and solves the distance
  problem
• 2003 GRB 030329/SN 2003dh-connection to SNe
• 2004-present Swift satellite has so far
  precisely localized more than 400 GRBs high
  redshift GRBs

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Brief History
Soviets? No!
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Brief History (cont.)
2704 BATSE Gamma-Ray Bursts
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Brief History (cont.)
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Classification
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Brief History (cont.)Nemiroff 1994118 models
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Beppo-SAX GRB 970228
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GRB 970228 Optical
Groot et al. 1997
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GRB 970508 Redshift!
Metzger et al. 1997z gt 0.835
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GRB 970508 Light curve
Galama et al. 1997
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Up close and personal with GRBs

• 1999 GRB 990510 jets in GRBs
• 2003 GRB 030329/SN 2003dh firm connection to
  core-collapse supernovae and death of massive
  stars
• 2006 No mass extinction on Earth due to GRBs

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GRB 990510
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GRB 990510 Light Curve
Stanek et al. 1999
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Theoretical Insight
z0.0335
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Internal-External Shock Model for Long GRBs
Internal collisions Internal Shocks
External Shocks
ISM

GRB
Afterglow
Stanek et al. 1999
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Afterglows broken light curves suggest jets
Edge effect
Sideways expansion
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GRB 030329 Light Curve
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GRB-SN Connection The Smoking gun GRB
030329/SN 2003dh
tSN-tGRB2days.
Stanek et al. (2003) Matheson et al. (2003)
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(No Transcript)
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Nature of GRB Progenitors
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GRB 060218/SN 2006aj (Modjaz et al. 2006)
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z0.0335
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GRB vs. SN Hosts with HST
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Fruchter et al. (2006)
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Local GRB Hosts
Stanek et al. (2006)
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Local GRB Hosts
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Stanek et al. (2006)
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Killer GRBs?
NO!
Ohio State University astrophysicist Kris Stanek
on extremely low probabilities of nearby massive
interstellar explosions Now we can conclusively
say there is a better chance you will get shot in
the face by Dick Cheney than Earth getting hit
with a gamma ray burst. SEED Magazine Dec/Jan
2007
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Stellar Evolution
GRB if Fe/H low
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Swift GRB Mission

• Launched in Nov. 2004. Spacecraft will have a
  lifetime to orbital decay of 8 yr.
• Instruments
• Burst Alert Telescope (BAT)(15-150kev)(1-4)
• X-ray Telescope (XRT) (0.2-10kev)(5)
• Ultraviolet/Optical Telescope (UVOT)
  (170-600nm)(0.3)

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Observing Strategy

• BAT triggers on GRB, calculates position to lt 4
  arcmin
• Spacecraft autonomously slews to GRB position in
  20-70 s
• XRT determines position to lt 5 arcseconds
• UVOT images field, transmits finding chart to
  ground

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Gamma-ray Coordinates Network
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LBT
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GRB 070125
Garnavich et al. (2007)
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GRB 070125
Garnavich et al. (2007)
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GRB 050904z6.295
The prompt optical/near-infrared flare of GRB
050904 the most luminous transient ever
detected Kann et al. (2007)
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z8.2
GRB 090423
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GRB 080318Bz0.937
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Classification Again
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The Consensus

• Short(-hard) Bursts
• Merger of compact objects (neutron stars, BHs)
• Found in old and young stellar population

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Future GRB Mysteries?
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