recent grb results from swift
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John Cannizzo/UMBC/Goddard LSC Meeting, Hanford, WA August 16, 2005 LIGO-G050431-00-Z. Recent GRB Results from Swift. GRBs Trace Comoving Volume. dV/dz = 4πD 2 (z) dD(z)/dz. 36 pre-Swift: =1.4, σ(z)=1.0 7 Swift + 2 other: =2.3, σ(z)=1.3. GRB Rate:. - PowerPoint PPT PresentationTRANSCRIPT
G O D D A R D S P A C E F L I G H T C E N T E R1
Recent GRB Results from Swift
John Cannizzo/UMBC/GoddardLSC Meeting, Hanford, WA
August 16, 2005
LIGO-G050431-00-Z
G O D D A R D S P A C E F L I G H T C E N T E R2
GRBs Trace Comoving Volume
dV/dz = 4πD2(z) dD(z)/dz
36 pre-Swift: <z>=1.4, σ(z)=1.0 7 Swift + 2 other: <z>=2.3, σ(z)=1.3
G O D D A R D S P A C E F L I G H T C E N T E R3
Frail et al. (2001)
[1] V(z<10) = 4x103 Gpc3
GRB Rate:
[2] Luminosity Density (V band) = 2x1017 L° Gpc-3
=> about 1010 galaxies
[3] Rate(BATSE) ~103 yr-1
So, rate per galaxy is about 1 in 107 yr.
G O D D A R D S P A C E F L I G H T C E N T E R4
Long GRBs: Jet from a Collapsar(Weiqun Zhang - Stanford)
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G O D D A R D S P A C E F L I G H T C E N T E R5
Short GRBs: NS-NS Merger (Max Ruffert - University of Edinburgh)
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G O D D A R D S P A C E F L I G H T C E N T E R6
BAT+XRT 2-10 keV Decay; f=f0t-α
Barthelmy et al. (2005)
G O D D A R D S P A C E F L I G H T C E N T E R7
Interpretation: “Curvature Effect”
Kumar & Panaitescu (2000):
G O D D A R D S P A C E F L I G H T C E N T E R8
First Localization of a Short GRB
• GRB050509b: 40 ms duration (BAT), soft part of the short/hard population
• XRT: 11 photons (10σ sig.)
• z=0.225 elliptical galaxy
• chance probability ~10-4
• Eiso=1.1x1048 erg (15-150 keV)
• ~102 E(2004 Dec 27 SGR flare)
• --> supports NS-NS merger
Gehrels et al. (2005)
G O D D A R D S P A C E F L I G H T C E N T E R9
Summary
• GRBs trace comoving volume of the Universe, which exhibits a maximum at z~1-2.
• In two cases, the prompt emission seen in BAT+XRT forms a continuous decay with t-α, where α~3, consistent with “curvature radiation” effect.
• Localization of one short GRB appears to be in a luminous, non-star forming elliptical galaxy, consistent with NS-NS merger theory.