6,273 research outputs found
Time Domain Studies of X-ray Shot Noise in Cygnus X-1
We investigate the variability of Cygnus X-1 in the context of shot moise
models, and employ a peak detection algorithm to select individual shots. For a
long observation of the low, hard state, the distribution of time intervals
between shots is found to be consistent with a purely random process, contrary
to previous claims in the literature. The detected shots are fit to several
model templates and found to have a broad range of shapes. The fitted shots
have a distribution of timescales from below 10 milliseconds to above 1 second.
The coherence of the cross spectrum of light curves of these data in different
energy bands is also studied. The observed high coherence implies that the
transfer function between low and high energy variability is uniform. The
uniformity of the tranfer function implies that the observed distribution of
shot widths cannot have been acquired through Compton scattering. Our results
in combination with other results in the literature suggest that shot
luminosities are correlated with one another. We discuss how our experimental
methodology relates to non-linear models of variability.Comment: Accepted for publication in Astrophysical Journal on July 16, 200
Evolution of photon and particle spectra in compact, luminous objects
The physics of high energy photons and particles (especially electrons and positrons) in the compact, high-energy-density of galactic nuclei and quasars was investigated. A numerical code was developed which follows the nonlinear spectral evolution of a pair/photon plasma, due to two-body scattering and interaction process, in an unmagnetized system. The code was applied both to static plasmas and to relativistic expanding winds
Recommended from our members
Assessing high school students\u27 conceptions of the size, age, and distance of astronomical objects
The purpose of this research study is to identify student conceptions about the size, distance, and age of various objects associated with space science. After reviewing the literature related to this study, there seems to be a need for continued research at the high school level in the field of astronomy conceptualization
- …