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On the Dramatic Spin-Up/Spin-Down Torque Reversals in BATSE Observations of Accretion Powered Pulsars

Nelson, Robert W. and Vaughan, Brian A. and Bildsten, Lars and Chakrabarty, Deepto and Koh, Danny T. and Prince, Thomas A. and Finger, Mark H. and Wilson, Robert B. and Rubin, Bradley C. (1997) On the Dramatic Spin-Up/Spin-Down Torque Reversals in BATSE Observations of Accretion Powered Pulsars. In: Accretion Phenomena and Related Outflows. IAU Symposium Proceedings Series. No.163. Astronomical Society of the Pacific , San Francisco, CA, pp. 256-265. ISBN 9781886733411. http://resolver.caltech.edu/CaltechAUTHORS:20181115-131341275

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Abstract

X-ray pulsars are the only accreting magnetic stars where rotation torques induced by accretion are large enough to be measured on short timescales ~ days. They are thus unique laboratories for studying the interaction between an accretion disk and a stellar magnetosphere. We describe 5 years of continuous pulsar timing observations by the BATSE instrument on GRO which paint a strikingly different picture of pulsar spin behavior than understood from the previous 20 years of sparse observations. In particular, we find that more than half of the persistent pulsars we observe undergo dramatic torque reversals, switching suddenly between extended periods of steady spin-up and steady spin-down. Moreover, variations in pulsed flux are anticorrelated with torque in at least one system undergoing secular spin-down, GX1+4. This behavior contradicts standard accretion torque theory (Ghosh and Lamb 1979). A simple – albeit unconventional – hypothesis which naturally explains these observations is that the disks in these systems somehow alternate between epochs of prograde and retrograde rotation.


Item Type:Book Section
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https://doi.org/10.1017/s025292110004272xDOIArticle
ORCID:
AuthorORCID
Prince, Thomas A.0000-0002-8850-3627
Additional Information:© Astronomical Society of the Pacific 1997.
Group:Space Radiation Laboratory, TAPIR
Record Number:CaltechAUTHORS:20181115-131341275
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181115-131341275
Official Citation:Nelson, R., Vaughan, B., Bildsten, L., Chakrabarty, D., Koh, D., Prince, T., . . . Rubin, B. (1997). On the Dramatic Spin-Up/Spin-Down Torque Reversals in BATSE Observations of Accretion Powered Pulsars. International Astronomical Union Colloquium, 163, 256-265. doi:10.1017/S025292110004272X
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90922
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:16 Nov 2018 19:03
Last Modified:16 Nov 2018 19:03

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