19,733 research outputs found
On the Kinematics of GRB980425 and its association with SN1998bw
In this paper I put forward a model in which GRB980425 is both associated
with SN1998bw and is also a standard canonical (long; ~seconds) gamma-ray
burst. Herein it is argued that if gamma-ray bursts are relativistic jets with
the fastest moving material at the core, then the range of observed jet
inclinations to the line-of-sight produces a range in the observed properties
of GRBs, i.e. the lag-luminosity relationship. In particular, if the jet
inclination is high enough, the observed emitter will move slowly enough to
render relativistic beaming ineffective, thus distinguishing the jet from
apparent isotropic emission. Thus we expect a break in the lag-luminosity
relationship. I propose that GRB980425 defines that break. The position of this
break gives important physical parameters such as the Lorentz factor
(\gamma_max ~ 1000), the jet opening angle (~1 degree), and thus the beaming
fraction (~10^-4). Estimates of burst rates are consistent with observation. If
correct, this model is evidence in favor of the collapsar mode as the
progenitor of cosmological, long gamma-ray bursts.Comment: 7 pages, including 1 figure. Submitted to ApJ Letter
Status of Matter-Gravity Couplings in the SME
Constraints on Lorentz violation in matter-gravity couplings are summarized
along with existing proposals to obtain sensitivities that exceed current
limits by up to 11 orders of magnitude.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 17-21, 201
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