Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRBs, Fireballs and Precessing Gamma Jets   Fireballs are huge isotropic explosions models widely believed to explain
Gamma Ray Burst, GRBs (Piran,1999); ever-new versions consider wide beamed
(10^o) Jet explosions hitting external shells. On the contrary, since
1994-1998, we argued (Fargion 1995-2000; see also Blackman et all.1996) that
GRBs (as well as Soft Gamma Repeaters SGR) are spinning and precessing Gamma
Jets, produced by collimated e^+,e^- Jet via Inverse Compton Scattering, in a
very narrow (0.1^o) angles, blazing and flashing the observer. The Jet arises
in Super-Nova (SN) explosions; its energy decays slowly from earliest SN powers
(corresponding to GRB) toward lower stable power as Soft Gamma Repeaters (SGR)
regimes. GRBs and SGRs shared (sometimes) same spectra and time structure: then
SGRs are low-power GRBs, but without SN relics (or GRB afterglows, signatures
of Jets in SN-GRBs). Moreover weak isolated X-ray precursor signals,(such as
GRB980519, GRB981226,GRB000131), corresponding to huge isotropic, sim 10^{47}
erg s^{-1}, followed by the extreme GRB, sim {10^{52}} erg s^{-1} powers,
disagree with any Fireball explosive scenarios. We naturally interpret these
X-Ray precursors as rare earliest marginal blazes of outlying X conical
precessing Jet tails, surrounding the gamma Jet, later hitting in-axis as a
GRB.

2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th