10,405 research outputs found
Convergence on Gauss-Seidel iterative methods for linear systems with general H-matrices
It is well known that as a famous type of iterative methods in numerical
linear algebra, Gauss-Seidel iterative methods are convergent for linear
systems with strictly or irreducibly diagonally dominant matrices, invertible
matrices (generalized strictly diagonally dominant matrices) and Hermitian
positive definite matrices. But, the same is not necessarily true for linear
systems with nonstrictly diagonally dominant matrices and general matrices.
This paper firstly proposes some necessary and sufficient conditions for
convergence on Gauss-Seidel iterative methods to establish several new
theoretical results on linear systems with nonstrictly diagonally dominant
matrices and general matrices. Then, the convergence results on
preconditioned Gauss-Seidel (PGS) iterative methods for general matrices
are presented. Finally, some numerical examples are given to demonstrate the
results obtained in this paper
Detectable MeV neutrinos from black hole neutrino-dominated accretion flows
Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black
holes (BHs) have been theorized as the central engine of relativistic jets
launched in massive star core collapse events or compact star mergers. In this
work, we calculate the electron neutrino/anti-neutrino spectra of NDAFs by
fully taking into account the general relativistic effects, and investigate the
effects of viewing angle, BH spin, and mass accretion rate on the results. We
show that even though a typical NDAF has a neutrino luminosity lower than that
of a typical supernova (SN), it can reach
peaking at MeV, making them potentially detectable with the upcoming
sensitive MeV neutrino detectors if they are close enough to Earth. Based on
the observed GRB event rate in the local universe and requiring that at least 3
neutrinos are detected to claim a detection, we estimate a detection rate up to
(0.10-0.25) per century for GRB-related NDAFs by the Hyper-Kamiokande
(Hyper-K) detector if one neglects neutrino oscillation. If one assumes that
all Type Ib/c SNe have an engine-driven NDAF, the Hyper-K detection rate would
be (1-3) per century. By considering neutrino oscillations, the
detection rate may decrease by a factor of 2-3. Detecting one such event would
establish the observational evidence of NDAFs in the universe.Comment: 7 pages, 2 figures, 2 tables, accepted for publication in PR
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