Gamma-ray bursts from high-velocity neutron stars

Li, Hui; Dermer, C. D.

doi:10.1038/359514a0

Cited by 49 publications

(40 citation statements)

References 22 publications

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“…Cosmological models [4] are subject to a rather tight energy constraint at the burst sources 151. In the cosmological scenario, the deviation of the slope of from -1 (for a homogeneous distribution in the Euclidean space) or ( V/V,,, ) < 0.5 is naturally explained [6] while in the halo scenario some special radial distributions are required [3,7]. The lack of source identifications with counterparts is puzzling in the cosmological scenario since any sources residing in galaxies could have been identified with their hosts.…”

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confidence: 99%

Relativistic bulk motion and statistics of beamedγ-ray bursts

1993

Phys. Rev. D

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y-ray bursts may be from jetlike sources in relativistic bulk motion. In this case, the emisison of y rays is strongly beamed along the direction of the bulk motion. We analyze effects of the relativistic bulk motion and the resulting beamed emission on statistics of the y-ray bursts. PACS number(s1: 98.70.Rz, 98.62.Nx, 98.80.H~ The physical origin of y-ray bursts (GRB's) has remained elusive. Major difficulties are mainly due to lack of positive identifications of GRB's with known astrophysical counterparts and to uncertain distance scales. BATSE's (Burst and Transient Source Experiment's) relatively low detection threshold (F,,, = lo-' erg/s cm2) and homogeneous detection have facilitated meaningful statistical analyses [I]. The isotropy of G R B sky positions [2] poses a serious difficulty for galactic or extended halo models [3]. Cosmological models [4] are subject to a rather tight energy constraint at the burst sources 151. In the cosmological scenario, the deviation of the slope of from -1 (for a homogeneous distribution in the Euclidean space) or ( V/V,,, ) < 0.5 is naturally explained [6] while in the halo scenario some special radial distributions are required [3,7]. The lack of source identifications with counterparts is puzzling in the cosmological scenario since any sources residing in galaxies could have been identified with their hosts.If y-ray emission is isotropic, the luminosity L of a burst from a source at a redshift z,km/s Mpc (for our discussions, h =0.5), and a= 1-2 is the photon index [6]. Isotropic y-ray emission from a typical cosmological burst at z -1 roughly requires a total burst energy -10'' erg or a fluence > lo-' erg/cm2. This large energy with short emission time scales [min (duration, variability time scale)] implies that some physics is required for yray photoris to escape from the emission region at all [ S ] . However, if emission is from a jetlike source in relativistic bulk motion, this severe energy constraint could be and ( V/V,,, ) avoided [5,8]. Since no other models convincingly predict relativistically moving sources, plausible candidates could be rare jets with high Lorentz factors from faint unidentified extragalactic objects [quasistellar objects (QSO's) or active galactic nuclei (AGN)]. If extragalactic objects are indeed involved, identification of GRB's with (x-ray, optical, IR, or radio) counterparts is likely. The relativistic bulk motion motivates a physically meaningful G R B luminosity distribution [9], which is otherwise rather arbitrary and unconstrained. We consider effects of relativistic bulk motion and resulting beamed emission on G R B statistics. We assume that sources emit radiation isotropically in their comoving frames. Our statistical analysis is independent of any specific emission mechanisms whose details will be addressed in a separate paper.We assume that sources are described either by a "standard candle" (a standard luminosity with a spectral index) or by a "standard source" (a standard Lorentz factor, a standard intrinsic luminosity in...

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confidence: 99%

Relativistic bulk motion and statistics of beamedγ-ray bursts

1993

Phys. Rev. D

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“…Following the discovery by BATSE that the faint bursts are distributed isotropically on the sky, Galactic halo and corona models found new flavor (see, e.g., (9,(21)(22)(23)(24)) as an attractive way of reconciling all of the evidence about GRBs which favors Galactic neutron stars with isotropy. However, these models were considered somewhat ad hoc, particularly by advocates of cosmological models, because no means of producing large numbers of neutron stars in an extended Galactic halo was known [see, e.g.…”

Section: The Galactic Coronamentioning

confidence: 99%

“…Our detailed dynamical calculations of the Galaxy show that a distant corona of high velocity neutron stars can easily account for the isotropic angular distribution and the brightness distribution of GRBs ( Figure 2) [see also (23,29,30)]. …”

Section: Sky and Brightness Distributions Of Burstsmentioning

confidence: 99%

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Galactic models of gamma-ray bursts

Lamb¹,

Bulik²,

Coppi³

1996

AIP Conference Proceedings

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“…Burst sources in an extended Galactic corona may either be neutron stars born with high-velocity 600 800 km s ,1 in the disk 7,8 or an old population born in the halo. 1 At distances of 100 kpc, luminosities of 10 40 1 0 41 erg s ,1 are required, well above the Eddington luminosity of a neutron star.…”

Section: Gamma-ray Burstsmentioning

confidence: 99%

<title>Andromeda: a mission to determine the gamma-ray burst distance scale</title>

et al. 1995

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Andromeda is a wide-eld, imaging, hard X-ray soft gamma-ray instrument capable of detecting gamma-ray bursts GRBs a factor 20 times fainter than GRO BATSE. During 1-year of a two-year mission, it could determine whether GRBs are Galactic or cosmological in origin by searching for an excess of bursts towards the nearby Andromeda galaxy M31. As a pointed, imaging instrument with sensitivity in the 10|200 keV band signi cantly better than previous coded-aperture instruments, Andromeda is capable of carrying out important secondary science objectives: for example, studying the soft-gamma-repeater and X-ray transient populations of M31 and the Galactic bulge. Andromeda is a coded aperture gamma-ray telescope consisting of a hexagonal coded mask coupled to an alkalihalide imaging scintillation detector, a ight-proven technology adapted from the balloon-borne Caltech Gamma-Ray Imaging Payload GRIP. The new instrument is optimized for the 10 200 keV band and has 1:5 angular resolution ove r a 1 7 FWHM eld of view. Andromeda is designed to be a small, lowcost mission, and draws its design largely from existing instrumentation. Andromeda was submitted to the STEDI program, and will also be proposed as a NASA Small Explorer.

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Gamma-ray bursts from high-velocity neutron stars

Cited by 49 publications

References 22 publications

Relativistic bulk motion and statistics of beamedγ-ray bursts

Relativistic bulk motion and statistics of beamedγ-ray bursts

Galactic models of gamma-ray bursts

<title>Andromeda: a mission to determine the gamma-ray burst distance scale</title>

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