Quick search Find article
Quick search
Find article

The Halo Beaming Model for Gamma-Ray Bursts

FREE

R. C. Duncan1 and Hui Li2

Show affiliations


We 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 phib 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 phib = 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 (lesssim2 σ).

The HBM makes the distinctive prediction that the galactocentric quadrupole moment langcos2 Θrang - \frac {1}{3} for bright, nearby GRBs is large, even though the dipole moment langcos Θrang 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 (phib ≈ 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.


Subject headings

Galaxy: halo; gamma rays: bursts; stars: magnetic fields; stars: neutron


Dates

Issue 2 (1997 August 1)

Received 1996 October 11, accepted for publication 1997 February 27



  1. The Halo Beaming Model for Gamma-Ray Bursts

    R. C. Duncan and Hui Li 1997 ApJ 484 720

  2. From spinning to non-spinning cosmic string spacetime

    V A De Lorenci et al 1999 Class. Quantum Grav. 16 3047

  3. Numerical Simulations of Equatorially Asymmetric Magnetized Supernovae: Formation of Magnetars and Their Kicks

    Hidetomo Sawai et al. 2008 ApJ 672 465

  4. Statistics of thermal to shot noise crossover in chaotic cavities

    Vladimir Al Osipov and Eugene Kanzieper 2009 J. Phys. A: Math. Theor. 42 475101

  5. The Initial Mass Function in the Taurus Star-forming Region

    César Briceño et al. 2002 ApJ 580 317

  6. The single-phase multiferroic oxides: from bulk to thin film

    W Prellier et al 2005 J. Phys.: Condens. Matter 17 R803

  7. Spitzer IRS Spectroscopy of Intermediate Polars: Constraints on Mid-Infrared Cyclotron Emission

    Thomas E. Harrison et al. 2007 ApJ 656 444

  8. Simultaneous particle image velocimetry and synthetic schlieren measurements of an erupting thermal plume

    Christian F Ihle et al 2009 Meas. Sci. Technol. 20 125402

  9. Nuclear Partition Functions at Temperatures Exceeding 1010 K

    T. Rauscher 2003 ApJS 147 403

  10. High-temperature structural studies of PbBi2M2O9 (M = Nb and Ta)

    Rene Macquart et al 2002 J. Phys.: Condens. Matter 14 7955

View by subject




Export








Please login to access our web services, or create an account if you don't yet have one.

You must have cookies enabled in your web browser to be able to login.

Username
Password

Forgotten your password? Get a new one here.