2026-09-21T14:42:14Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/18855 2023-07-10 col_2142_8859 col_2142_5131 com_2142_8858 com_2142_234 com_2142_5130

Lamb, Frederick K. Daumerie, Pascal R. 2011-04-21T13:35:05Z 2011-04-21T13:35:05Z 10000-01-01 1996 Binary X-ray pulsars are strongly magnetic neutron stars accreting matter from a companion star. The strong magnetic fields of the neutron stars guide the accreting plasma to the magnetic poles, and X-ray pulsations result from the rotation of the beamed emission at the magnetic poles through the line of sight. In many systems, accretion proceeds via a Keplerian accretion disk. The differential rotation of the disk and star creates magnetic stresses that disrupt the Keplerian flow, and bring the plasma into corotation with the neutron star well above the stellar surface. We report the results of a detailed numerical study of the interaction of a slim Keplerian accretion disk with the magnetic field of an aligned rotator. We show that the accretion flow generally exhibits a sonic point because of the large radial velocity the disk plasma acquires following the loss of centrifugal support caused by magnetic braking of the plasma in the accretion disk. Our model includes, for the first time, the effect of the rotation of the neutron star on the disk flow, and allows us to compute the location of the inner edge of the Keplerian flow and the torque on the neutron star as functions of the stellar spin frequency. In a preliminary calculation, we assume that the poloidal component of the magnetic field interacting with the disk is dipolar; in an improved treatment, we include the screening effect of the electrical currents induced in the disk. We model the field-aligned flow of plasma from the inner disk to the magnetic poles of the neutron star. vVe calculate the electrical current density in this region, and we estimate the screening effect of these currents. We discuss the implications of our results for the spin frequency behavior of X-ray pulsars accreting from disks. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-04-21T13:35:05Z No. of bitstreams: 1 1996_daumerie.pdf: 3479852 bytes, checksum: cf274db54427da3d1985f71776350e79 (MD5) Made available in DSpace on 2011-04-21T13:35:05Z (GMT). No. of bitstreams: 1 1996_daumerie.pdf: 3479852 bytes, checksum: cf274db54427da3d1985f71776350e79 (MD5) Previous issue date: 1996 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-04-21T13:35:05Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:09:44-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 4011032 http://hdl.handle.net/2142/18855 en 1996 Pascal R. Daumerie binary X-ray pulsars neutron stars Keplerian accretion disk x-rays disk-magnetosphere interaction Disk-magnetosphere interaction in X-ray binaries Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.