R. C. Duncan and Hui Li 1997 ApJ 484 720 doi:10.1086/304364
R. C. Duncan1 and Hui Li2
Show affiliationsWe consider a model for gamma-ray bursts (GRBs) from high-velocity neutron stars in the Galactic halo. In this model, bursters are born in the Galactic disk with large recoil velocities Vr, and GRBs are beamed to within emission cones of half-angle
b centered on Vr. We describe scenarios for magnetically channeled GRBs that have such beaming characteristics. We then make detailed comparisons of this halo beaming model (HBM) to data from the Third BATSE Catalog and from the Pioneer Venus Orbiter experiment, for both GRB intensity and angular position distributions. Acceptable fits to observations of over 1000 bursts are obtained for
b = 15°-30° and for a BATSE sampling depth of D ~ 180 kpc, which corresponds to a peak burst luminosity of ~1040 ergs s-1. Present data favor a truly isotropic (cosmological) model over the HBM but not by a statistically compelling margin (
2 σ).
The HBM makes the distinctive prediction that the galactocentric quadrupole moment
cos2 Θ
-
for bright, nearby GRBs is large, even though the dipole moment
cos Θ
remains near zero. Bursters born in nearby external galaxies, such as M31, are almost entirely undetectable in the HBM because of misdirected beaming. We analyze several refinements of the basic HBM: gamma-ray intensities that vary with angle from the beam axis; non-standard candle GRB luminosity functions; and models including a subset of bursters that do not escape from the Galaxy. We also discuss the energy budgets for the bursters, the origins of their recoils, and the physics of burst beaming and alignment. One possible physical model is based on the magnetar model of soft gamma repeaters (SGRs). Empirical bounds on the rate of formation and peculiar velocities of SGRs imply that there exist ~104 to ~107 aged SGRs in the Galactic halo within a distance ~100 kpc.
The HBM gives an acceptable fit to observations only if it satisfies some special conditions (
b ≈ 20°; uniform bursting rate) that are possible, but for which there are no clear and compelling theoretical justifications. The cosmological burst hypothesis is more generic and thus more attractive in this sense.
Galaxy: halo; gamma rays: bursts; stars: magnetic fields; stars: neutron
Issue 2 (1997 August 1)
Received 1996 October 11, accepted for publication 1997 February 27
R. C. Duncan and Hui Li 1997 ApJ 484 720
V A De Lorenci et al 1999 Class. Quantum Grav. 16 3047
Hidetomo Sawai et al. 2008 ApJ 672 465
Vladimir Al Osipov and Eugene Kanzieper 2009 J. Phys. A: Math. Theor. 42 475101
César Briceño et al. 2002 ApJ 580 317
W Prellier et al 2005 J. Phys.: Condens. Matter 17 R803
Thomas E. Harrison et al. 2007 ApJ 656 444
Christian F Ihle et al 2009 Meas. Sci. Technol. 20 125402
T. Rauscher 2003 ApJS 147 403
Rene Macquart et al 2002 J. Phys.: Condens. Matter 14 7955