13,002 research outputs found
Mass of the black hole in the Seyfert 1.5 galaxy H 0507+164 from reverberation mapping
We present the results of our optical monitoring campaign of the X-ray source
H 0507+164, a low luminosity Seyfert 1.5 galaxy at a redshift z = 0.018.
Spectroscopic observations were carried out during 22 nights in 2007, from the
21 of November to the 26 of December. Photometric observations in the R-band
for 13 nights were also obtained during the same period. The continuum and
broad line fluxes of the galaxy were found to vary during our monitoring
period. The R-band differential light curve with respect to a companion star
also shows a similar variability. Using cross correlation analysis, we
estimated a time delay of 3.01 days (in the rest frame), of the response of the
broad H-beta line fluxes to the variations in the optical continuum at 5100
angstroms. Using this time delay and the width of the H-beta line, we estimated
the radius for the Broad Line Region (BLR) of 2.53 x 10^{-3} parsec, and a
black hole mass of 9.62 x 10^{6} solar mass.Comment: 7 pages, 8 figures, Accepted for publication in MNRA
The Density Matrix Renormalization Group and the Nuclear Shell Model
We summarize recent efforts to develop an angular-momentum-conserving variant
of the Density Matrix Renormalization Group method into a practical truncation
strategy for large-scale shell model calculations of atomic nuclei. Following a
brief description of the key elements of the method, we report the results of
test calculations for Cr and Ni. In both cases we consider
nucleons limited to the 2p-1f shell and interacting via the KB3 interaction.
Both calculations produce a high level of agreement with the exact shell-model
results. Furthermore, and most importantly, the fraction of the complete space
required to achieve this high level of agreement goes down rapidly as the size
of the full space grows
Zeta-like Multizeta Values for higher genus curves
We prove or conjecture several relations between the multizeta values for
positive genus function fields of class number one, focusing on the zeta-like
values, namely those whose ratio with the zeta value of the same weight is
rational (or conjecturally equivalently algebraic). These are the first known
relations between multizetas, which are not with prime field coefficients. We
seem to have one universal family. We also find that interestingly the
mechanism with which the relations work is quite different from the rational
function field case, raising interesting questions about the expected motivic
interpretation in higher genus. We provide some data in support of the guesses.Comment: Expository revisions plus appendices containing proofs of more cases
of conjecture
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