20,275 research outputs found
Methods for detection and characterization of signals in noisy data with the Hilbert-Huang Transform
The Hilbert-Huang Transform is a novel, adaptive approach to time series
analysis that does not make assumptions about the data form. Its adaptive,
local character allows the decomposition of non-stationary signals with
hightime-frequency resolution but also renders it susceptible to degradation
from noise. We show that complementing the HHT with techniques such as
zero-phase filtering, kernel density estimation and Fourier analysis allows it
to be used effectively to detect and characterize signals with low signal to
noise ratio.Comment: submitted to PRD, 10 pages, 9 figures in colo
Complex Visibilities of Cosmic Microwave Background Anisotropies
We study the complex visibilities of the cosmic microwave background
anisotropies that are observables in interferometric observations of the cosmic
microwave background, using the multipole expansion methods commonly adopted in
analyzing single-dish experiments. This allows us to recover the properties of
the visibilities that is obscured in the flat-sky approximation. Discussions of
the window function, multipole resolution, instrumental noise, pixelization,
and polarization are given.Comment: 22 pages, 1 figure include
Robust Gravitational Wave Burst Detection and Source Localization in a Network of Interferometers Using Cross Wigner Spectra
We discuss a fast cross-Wigner transform based technique for detecting
gravitational wave bursts, and estimating the direction of arrival, using a
network of (three) non co-located interferometric detectors. The performances
of the detector as a function of signal strength and source location, and the
accuracy of the direction of arrival estimation are investigated by numerical
simulations.Comment: accepted in Class. Quantum Gravit
Orthogonal sets of data windows constructed from trigonometric polynomials
Suboptimal, easily computable substitutes for the discrete prolate-spheroidal windows used by Thomson for spectral estimation are given. Trigonometric coefficients and energy leakages of the window polynomials are tabulated
Supermassive Black Hole Mass Estimates Using Sloan Digital Sky Survey Quasar Spectra at 0.7 < z < 2
We present MgII-based black hole mass estimates for 27,602 quasars with
rest-frame UV spectra available in the Sloan Digital Sky Survey Data Release
Three. This estimation is possible due to the existence of an empirical
correlation between the radius of the broad line region and the continuum
luminosity at 3000 Angstroms. We regenerate this correlation by applying our
measurement method to UV spectra of low-redshift quasars in the HST/IUE
databases which have corresponding reverberation mapping estimates of the Hbeta
broad line region's radius. Our mass estimation method uses the line dispersion
rather than the full width at half maximum of the low-ionization MgII emission
line. We measure MgII line dispersions for quasars whose spectra have been
reconstructed using the most significant eigenspectra produced through
Principal Component Analysis. We have tested the reliability of using
reconstructed spectra in black hole mass estimation using a Monte Carlo
simulation and by comparing the results from original and reconstructed Data
Release Three spectra. We show that using reconstructed spectra not only makes
bias-free mass estimation possible for quasars with low spectroscopic
signal-to-noise ratio, but also reduces the intrinsic scatter of the
distribution of the black hole masses to lower than 0.15 dex.Comment: 38 Pages, 12 figures, 3 Tables, 1 hyperlink to catalogue data.
Accepted for publication in ApJ
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