236 research outputs found
THE BOGOLYUBOV-KRYLOV AVERAGING
International audienceWe present the modified approach to the classical Bogolyubov-Krylov averaging , developed recently for the purpose of PDEs. It allows to treat Lipschitz perturbations of linear systems with pure imaginary spectrum and may be generalized to treat PDEs with small nonlinearities
On Bounds of Eigenvalues of Complex Sturm-Liouville Boundary Value Problems
The paper is concerned with eigenvalues of complex Sturm-Liouville boundary value problems. Lower bounds on the real parts of all eigenvalues are given in terms of the coefficients of the corresponding equation and the bound on the imaginary part of each eigenvalue is obtained in terms of the coefficients of this equation and the real part of the eigenvalue
Unshifted Metastable He I* Mini-Broad Absorption Line System in the Narrow Line Type 1 Quasar SDSS J080248.18551328.9
We report the identification of an unusual absorption line system in the
quasar SDSS J080248.18551328.9 and present a detailed study of the system,
incorporating follow-up optical and NIR spectroscopy. A few tens of absorption
lines are detected, including He I*, Fe II* and Ni II* that arise from
metastable or excited levels, as well as resonant lines in Mg I, Mg II, Fe II,
Mn II, and Ca II. All of the isolated absorption lines show the same profile of
width km s centered at a common redshift as that of
the quasar emission lines, such as [O II], [S II], and hydrogen Paschen and
Balmer series. With narrow Balmer lines, strong optical Fe II multiplets, and
weak [O III] doublets, its emission line spectrum is typical for that of a
narrow-line Seyfert 1 galaxy (NLS1). We have derived reliable measurements of
the gas-phase column densities of the absorbing ions/levels. Photoionization
modeling indicates that the absorber has a density of and a column density of , and is located at
pc from the central super-massive black hole. The location of the absorber, the
symmetric profile of the absorption lines, and the coincidence of the
absorption and emission line centroid jointly suggest that the absorption gas
is originated from the host galaxy and is plausibly accelerated by stellar
processes, such as stellar winds \zhy{and/or} supernova explosions. The
implications for the detection of such a peculiar absorption line system in an
NLS1 are discussed in the context of co-evolution between super-massive black
hole growth and host galaxy build-up.Comment: 28 pages, 16 figures; accepted for publication in Astrophysical
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