8,617 research outputs found
Evidence for a Supernova in the Ic Band Light Curve of the Optical Transient of GRB 970508
Unique data on brightness curves of the OT of GRB 970508 obtained with
the 6-m telescope have been interpreted in the framework of the GRB-SN
(supernovae) connection. The effect must be maximal in the I_c band as OT GRB
970228. The peak absolute (M_B) magnitude of the suggested SN must be around
-19.5 for the OT of GRB 970508. If all or the main part of long GRBs are
associated with SNe, the GRB host galaxies (for ground-based observations, at
least) must be dimmer than the peak magnitude of the SN.Comment: 3 pages, 2 figures, oral presentation on 2nd Rome Workshop on
Gamma-Ray Bursts in the Afterglow Er
The gamma-ray bursts and core-collapse supernovae - global star forming rate peaks at large redshifts
This is a brief review on the first Gamma-Ray Bursts (GRB) optical
identifications - GRB host galaxies and Star Forming Rate (SFR) at relatively
small redshifts (z), on the metallicities of GRB hosts, the similarities and
differences between GRB hosts and galaxies at larger z, and on the SFR and GRB
rate (GRBR) at high z. Evidences of a direct connection between long-duration
GRBs and massive stars explosions (like Core-Collapse Super-Novae - CCSNe) are
presented. Is there a fast decrease in SFR up to z ~10? Some unsolved problems
related to GRBs are discussed: about the high-z GRB host galaxies, the high-z
CCSN-GRB connection, and possible new crucial cosmological tests at high z.Comment: 9 pages, 4 figures, to be published by "World Scientific" in
Proceedings of the XXIX International Workshop on High Energy Physics: New
Results and Actual Problems in Particle & Astroparticle Physics and Cosmology
(HEPFT2013), 26-28 June 2013, Protvino, Moscow region, Russi
On Construction of Recursion Operators From Lax Representation
In this work we develop a general procedure for constructing the recursion
operators fro non-linear integrable equations admitting Lax representation.
Svereal new examples are given. In particular we find the recursion operators
for some KdV-type of integrable equations.Comment: Latex File (AMS format), 23 pages, to be published in Journal of
Mathematical Physic
A Simple Mode on a Highly Excited Background: Collective Strength and Damping in the Continuum
Simple states, such as isobaric analog states or giant resonances, embedded
into continuum are typical for mesoscopic many-body quantum systems. Due to the
coupling to compound states in the same energy range, a simple mode acquires a
damping width ("internal" dynamics). When studied experimentally with the aid
of various reactions, such states reveal enhanced cross sections in specific
channels at corresponding resonance energies ("external" dynamics which include
direct decay of a simple mode and decays of intrinsic compound states through
their own channels). We consider the interplay between internal and external
dynamics using a general formalism of the effective nonhermitian hamiltonian
and looking at the situation both from "inside" (strength functions and
spreading widths) and from "outside" (S-matrix, cross sections and delay
times). The restoration of isospin purity and disappearance of the collective
strength of giant resonances at high excitation energy are discussed as
important particular manifestations of this complex interplay.Comment: 23 pages, LaTeX, 5 ps-figures included, to appear in PRC (Jule 1997
Integrable ODEs on Associative Algebras
In this paper we give definitions of basic concepts such as symmetries, first
integrals, Hamiltonian and recursion operators suitable for ordinary
differential equations on associative algebras, and in particular for matrix
differential equations. We choose existence of hierarchies of first integrals
and/or symmetries as a criterion for integrability and justify it by examples.
Using our componentless approach we have solved a number of classification
problems for integrable equations on free associative algebras. Also, in the
simplest case, we have listed all possible Hamiltonian operators of low order.Comment: 19 pages, LaTe
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