Gamma-Ray Bursts...
Phase 3
Add Transient Buffer Board
Dispersion delay helps catching up with
the burst
At 150 MHz, simultaneous with GRB if
DM > 265 for 48.8 s delay after burst
184 ms/DM @ 150 MHz
1660 ms/DM @ 50 MHz
Theory perspective
“True” prompt emission (Macquart
2007)
Precursor emission (Hansen &
Lyutikov 2001)
y
e
0:1
D
100 Mpc
22
B2=3
15
a25=2
7
:
6
n the range of the larger radio telescopes operating
gh somewhat less than the sensitivities of current
nt searches.
everal complications that may preclude generation of
on. If the neutron star is moving through a pre-
ma generated by the previous orbital cycles the
may be quenched, there will be no need to accelerate
les and the beam luminosity may drop to zero. In
formation of positronium in the magnetic fields
4 Â 1012 G (Usov & Melrose 1996; Arons 1998) may
the radio emission.
re, the generated radio emission may be absorbed in
rsphere. We expect that non-resonant Thomson
the low frequency
n ! nB
radio emission will not
because of the strong suppression s sT
n=nB
2
ering cross-section by the magnetic field at low
PAI R P LAS M A
Most of the energy liberated by the strong electric fields of
Section 2 is not radiated, but is instead released into the
magnetosphere of the slowly rotating magnetar in the form of
Alfve
Ân waves and a dense pair plasma. The energy release (see
equation 5) is a significant fraction of the local magnetic energy
density. In such a case, a wind, driven either by hydromagnetic or
plasma pressure is likely to result (Paczynski 1986, 1990; Melia &
Fatuzzo 1995; Katz 1996) while some will remain trapped, in a
fashion similar to that of the Soft Gamma Repeater picture of a
magnetically confined pair plasma (Thompson & Duncan 1995).
We envisage that the plasma released into regions of decreasing
field strength powers the wind while plasma released into regions
of increasing field strength will be trapped. Fig. 1 shows a
schematic version of our scenario.
Let us consider first the case of the wind. A release of energy at
the rate given by equation (5) results in a compactness parameter
h L=ac , 107B2
15
a27
: Thus, this is the same situation envisaged
in cosmological models for gamma-ray bursts (Goodman 1986;
ematic version of the energy extraction process. The motion of the companion through the magnetar field induces a plasma flow from the
o the magnetosphere. The pressure of this flow will drive a relativistic wind in those regions where the flow moves into a regime of weaker
plasma remains trapped in the case when it flows into a stronger field regime. The hot pair plasma will ablate some baryons off the surface of
r, providing a baryon-loaded sheath which regulates the cooling of the trapped plasma.
MNRAS 322, 695±701
Hansen & Lyutikov 2003
Motivation to use the TBB
transientskp
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