Dissertation > Excellent graduate degree dissertation topics show

Research on the Influence Factors of Pulsar Timing Residuals

Author: DuanMaoCheng
Tutor: CaiHongBing
School: Graduate School , Chinese Academy of Sciences ( National Time Service Center )
Course: Electronics and Communication Engineering
Keywords: pulsar timing residuals parameters error white noise
CLC: P145.6
Type: Master's thesis
Year: 2013
Downloads: 19
Quote: 0
Read: Download Dissertation

Abstract

Pulsar time-frequency standard is potential to be the astronomical time standard, theresearch on pulsar timing and navigation is more and more intensive and broad, the importantthing of which is to do timing residuals analysis. We can obtain the influence factors of thepulsar timing residuals according to the analysis in the time-domain and frequency-domain. Thenwe avoid or eliminate the errors influence to whiten residuals, to fit for the precise timing modeland to refine the timing model parameters and ground for the pulsar’s research.This thesis introduce the timing process circuit and fitting for timing model, then investigatethe influence of parameters errors and non-white noise on the timing residuals, in additionelaborate and verify the conclusion by theory and data analysis.To pulsar timing process, I combine data and replicate, eliminate dispersion, get highsignal-noise rate pulse profile and obtain the time of arrival(TOA). TOA is corrected bysubtracting delays and coordinate time, then I subtract timing pre-model with the TOA to get thetiming residuals, and I use the fitting routines, which are based on a linear singular-valuedecomposition, weighted least-squares algorithm, to search for optimal timing model, minimizethe residuals.Owing to the errors of the pulsar timing parameters, the precision of timing model will beinfluenced, and this canbe shown in the residuals. we illustrate influence of the errors of pulsar’srotation parameters, astrometric parameters and binary parameters on the timing residuals viadifferent residuals tendency, I find that rotation frequency, right ascension, declination andbinary orbital period will influent residuals evidently, so we should measure these parametersmore accurate. Simultaneously we can conjecture parameters errors by residuals tendenc y, thenremove them.Final we discuss whiten the residuals with timing noise. It’s to do spectrum analysis withfirst or second difference pre-whitening in residuals containing red noise, fit a spectral model tothe above spectral estimate and get combined covariance function by Fourier transform, thenobtain the Cholesky transform matrix to whiting residuals repeatedly. Second we discuss how towhiten residuals for which the red noise is comparable with the white noise. It’s to estimate thecovariance function directly, and whiting residuals by Cholesky solution. The research indicatethat Cholesky method white the residuals with red noise well. And comparing with the residualsbefore whiting, we can get the more precise parameters by fitting for the whited residuals.

Related Dissertations

CLC: > Astronomy,Earth Sciences > Astronomy > Astrophysics > Stellar physics > Pulsars ( neutron stars )
© 2012 www.DissertationTopic.Net Mobile