A study of recycled pulsars in globular clusters

[摘要] NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.We have performed a search for radio pulsars in 11 globular clusters visible from the 305 m Arecibo radio telescope. We have found 11 pulsars in the four clusters: M53, M13, NGC6760, and M15; each containing one binary pulsar: 1310+18A, 1639+36B, 1908+00A, and 2127+11C, respectively; as well as a total of seven isolated pulsars: 1639+36A, 2127+11B, 2127+11D, 2127+11E, 2127+11F[superscript 1], 2127+11G, 2127+11H[superscript 1].In this thesis we present the various search strategies employed and discuss the results of pulse time of arrival analysis for the seven isolated pulsars and the binary pulsar 2127+11C, as well as initial Doppler orbits for the binary pulsars 1310+18A and 1639+36B. The remaining pulsar 1908+00A is the subject of current research.The binary pulsar 2127+11C has been found to be in an 8 hour orbit about another degenerate star. The detection of a relativistic precession of the orbit and time dilation effects constrain the pulsar and companion star masses to be [massive pulsar] = 1.34 ± .23 [...] and [mass of companion] = 1.37 ± .23 [...].Study of the radial positions and anomalous spin period derivatives of the seven isolated pulsars in M15 has revealed otherwise unobtainable information on the structure of this post core collapsed globular cluster. From the observed spatial pulsar distribution of [...] it is inferred that the mass of isolated pulsars in M15 is approximately 1.4[...]. From the negative period derivative of PSR 2127+11A,D, it is inferred that the central mass-to-light ratio is > 1.9 [...] /[...] and the central mass density is > 2.7 x 10[superscript 6] [...]pc[superscript -3].From the observed isolated pulsar luminosity function in M15, [...] and an assumed minimum luminosity of 1.0 mJy kpc[superscript 2] it is inferred that the current population of observable isolated pulsars in M15 is [...](100).The observed dispersion measures towards the eight pulsars in M15 and their relative spatial positions indicate that the spectrum of inhomogeneities in the interstellar medium observed at smaller length scales, extends up to 10[superscript 17] cm.

[发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy

[关键词] Physics