GRB a New Tool for the Study of the Universe Expansion

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GRB a New Tool for the Study of the Universe
Expansion

• Guido Barbiellini and Francesco Longo
• University and INFN, Trieste
• In collaboration with A.Celotti and Z.Bosnjak
  (SISSA)

Venice 24th February 2005
XI International Workshop on "Neutrino
Telescopes"
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Outline

• Introduction
• GRB phenomenology
• Prompt Emission and Afterglow
• GRB standard fireball model
• GRB engine
• Energetics and Collimation
• Source models
• The fireworks model
• Spectral Energy correlations
• Peak Energy vs Total energy correlations
• Reproducing the BATSE fluence distribution
• GRB environment
• SN GRB connection
• The Compton tail
• Recent experimental evidences

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CGRO-BATSE (1991-2000)
CGRO/BATSE (25 keV10 MeV)
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Gamma-Ray Bursts
Temporal behaviour
Spectral shape
Spatial distribution
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BeppoSAX and the Afterglows

• Good Angular resolution (lt arcmin)
• Observation of the X-Afterglow

Costa et al. (1997)

• Optical Afterglow (HST, Keck)
• Direct observation of the host galaxies
• Distance determination

Kippen et al. (1998)
Djorgoski et al. (2000)
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The Fireball Model
Cartoon by Piran (1999)
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GRB progenitors
GRB 020813 (credits to CXO/NASA)
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Afterglow Observations
Harrison et al (1999)
Achromatic Break
Woosley (2001)
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Jet and Energy Requirements
Frail et al. (2001)
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Jet and Energy Requirements
Bloom et al. (2003)
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Collapsar model
Woosley (1993)

• Very massive star that collapses in a rapidly
  spinning BH.
• Identification with SN explosion.

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B field Vacuum Breakdown
Blandford Znajek (1977) Brown et al.
(2000) Barbiellini Longo (2001) Barbiellini,
Celotti Longo (2003)
Blandford-Znajek mechanism
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Vacuum Breakdown
The GRB energy emission is attributed to an high
magnetic field that breaks down the vacuum
around the BH and gives origin to a e? fireball.
Polar cap BH vacuum breakdown
Pair production rate
Figure from Heyl 2001
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Two phase expansion
The first phase of the evolution occurs close to
the engine and is responsible of energizing and
collimating the shells. It ends when the external
magnetic field cannot balance the radiation
pressure.

• Phase 1 (acceleration and collimation) ends when
  
• Assuming a dependence of the B field
• this happens at
• Parallel stream with
• Internal temperature

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Two phase expansion
The second phase of the evolution is a radiation
dominated expansion.

• Phase 2 (adiabatic expansion) ends at the radius
• Fireball matter dominated
• R2 estimation
• Fireball adiabatic expansion

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Jet Angle estimation
The fireball evolution is hypothized in analogy
with the in-flight decay of an elementary
particle.

• Lorentz factors
• Opening angle
• Result

Figure from Landau-Lifšits (1976)
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Energy Angle relationship
The observed angular distribution of the fireball
Lorentz factor is expected to be anisotropic.
Predicted Energy-Angle relation
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Spectral Energy correlations
Amati et al. (2002) Ghirlanda et al. (2004)
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GRB for Cosmology
Ghirlanda et al. (2004)
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GRB for Cosmology
Ghirlanda et al. 2005
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Testing the correlations
(Band and Preece 2005)
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GRB fluence distribution
GRB RATE?SFR
Madau Pozzetti 2000
FLUENCE DISTRIBUTION USING AMATI RELATION
By random extraction of Epeak (Preece et al.
2000) and GRB redshift for a sample of GRBs we
reproduce bright GRB fluence distribution.
Bosnjak et al. (2004)
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Testing the correlations
Bosnjak et al. astro-ph/0502185
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Testing the correlations
Bosnjak et al. astro-ph/0502185
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Testing the correlations
Ghirlanda et al. astro-ph/0502186
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SN- GRB connection
SN evidence
SN 1998bw - GRB 980425 chance coincidence
O(10-4) (Galama et al. 98)
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GRB 030329 the smoking gun?
(Matheson et al. 2003)
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Bright and Dim GRB

• (Connaughton 2002)

Q cts/peak cts

• BRIGHT GRB
• ? DIM GRB

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GRB tails

• Connaughton (2002), ApJ 567, 1028
• Search for Post Burst emission in prompt GRB
  energy band
• Looking for high energy afterglow (overlapping
  with prompt emission) for constraining
  Internal/External Shock Model
• Sum of Background Subtracted Burst Light Curves
• Tails out to hundreds of seconds decaying as
  temporal power law ? 0.6 ? 0.1
• Common feature for long GRB
• Not related to presence of low energy afterglow

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GRB tails
Sum of 400 long GRB bkg subtracted peak alligned
curve
Connaughton 2002
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GRB tails
Dim Bursts
Bright Bursts
Connaughton 2002
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Bright and Dim Bursts

• 3 equally populated classes
• Bright bursts
• Peak counts gt1.5 cm-2 s-1
• Mean Fluence 1.5 ? 10-5 erg cm-2
• Dim bursts
• peak counts lt 0.75 cm-2 s-1
• Mean fluence 1.3 ? 10-6 erg cm-2
• Mean fluence ratio 11

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Bright and Dim GRB
Q cts/peak cts

• BRIGHT GRB
• ? DIM GRB

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The Compton Tail
Barbiellini et al. (2004) MNRAS 350, L5
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The Compton tail

• Prompt luminosity
• Compton Reprocessed luminosity
• Q ratio

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Bright and Dim Bursts

• Bright bursts (tail at 800 s)
• Peak counts gt1.5 cm-2 s-1
• Mean Fluence 1.5 ? 10-5 erg cm-2
• Q 4.0 ? 0.8 10-4 (5 ?) fit over PL
• ? 1.3
• Dim bursts (tail at 300s)
• peak counts lt 0.75 cm-2 s-1
• Mean fluence 1.3 ? 10-6 erg cm-2
• Q 5.6 ? 1.4 10-3 (4 ?) fit over PL
• ? 2.8
• Mean fluence ratio 11
• Compton correction
• Corrected fluence ratio 2.8 (z or Epeak?)

R 1015 cm ?R R ? 0.1
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Recent evidences
GRB 011121
Piro et al. (2005)
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Recent evidences
GRB 011121
Piro et al. (2005)
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Effect of Attenuation
Epeak
Preliminary
Ep Eg0.7
Ep Eg
Tau 1.5 - 0.5 Caution scaling fluence and
Epeak
Egamma
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Effects on Hubble Plots
Preliminary
Luminosity distance
Reducing the scatter
Redshift
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Effects on Hubble Plots
Luminosity distance
Preliminary
Redshift
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Conclusions

• Cosmology with GRB requires
• Spectral Epeak determination
• Measurement of Jet Opening Angle
• Evaluation of environment material
• Waiting for Swift results