1,721,058 research outputs found
An analysis of the red noise in the power spectrum of X-ray binaries as a shot noise process.
No full textThe authors have simulated, using a Monte Carlo method, time series
representing the aperiodic variability typically observed in some X-ray
sources. They have supposed that such red-noise features are generated
by a shot noise process. The resulting time series have been analyzed by
fast Fourier transform techniques. Using different sets of parameters
they have been able to generate power spectra of different shapes. Some
preliminary results of these simulations are discussed
Numerical simulations of X-ray binary pulse profiles.
No full textThe authors investigate the physical features of the accretion process
in magnetic X-ray binaries. The characteristics of the accretion column
and the geometrical modulation effects due to the neutron star spin
determine the shape of the pulse profile. In order to constrain the
possible scenarios, the authors produce numerical simulations of the
X-ray pulse profile, in different energy bands. As an example they
reproduce the pulse profile and hardness ratio curve of X Per. Fan
emission from a hollow section of cone, along with a non-thermal
component can reproduce the observed data of this source
High resolution and broad band spectra of low mass X-ray binaries: a comparison between black holes and neutron stars
No full textA common question about compact objects in high energy astrophysics is whether it is possible to distinguish black hole from neutron star systems with some other property that is not the mass of the compact object. Up to now a few characteristics have been found which are typical of neutron stars (like quasi periodic oscillations at kHz frequencies or type-I X-ray bursts), but in many respects black hole and neutron star systems show very similar behaviors. We present here a spectral study of low mass X-ray binaries containing neutron stars and show that these systems have spectral characteristics that are very similar to what is found for black hole systems. This implies that it is unlikely we can distinguish between black holes and neutron stars from their X-ray spectra, except for the fact that black hole systems show sometimes a more extreme behavior with respect to neutron star systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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