On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars
In this study, we investigated the time-independent dynamics (disc structure, forces and torques) of a quasi-Keplerian disc around a millisecond pulsar (MSP) with an internal dynamo. We considered the disc around a MSP to be divided into the inner, middle and outer regions. By assuming that the di...
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Indian Academy of Sciences
2020
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| Online Access: | http://hdl.handle.net/20.500.12493/463 |
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| author | Isaac, Habumugisha Solomon, B. Tessema Edward, Jurua Simon, K. Anguma |
| author_facet | Isaac, Habumugisha Solomon, B. Tessema Edward, Jurua Simon, K. Anguma |
| author_sort | Isaac, Habumugisha |
| collection | KAB-DR |
| description | In this study, we investigated the time-independent dynamics (disc structure, forces and torques)
of a quasi-Keplerian disc around a millisecond pulsar (MSP) with an internal dynamo. We considered the
disc around a MSP to be divided into the inner, middle and outer regions. By assuming that the disc matter
flows in a quasi-Keplerian motion, we derived analytical equations for a complete structure (temperature,
pressure, surface density, optical depth and magnetic field) of a quasi-Keplerian thin accretion disc, and the
pressure gradient force (PGF). In our model, the MSP-disc interaction results into magnetic and material
torques, such that for a given dynamo ( ) and quasi-Keplerian (n) parameter, we obtained enhanced spin-up
and spin-down torques for a chosen star spin period. Results obtained reveal that PGF results into episodic
torque reversals that contribute to spinning-up or spinning-down of a neutron star, mainly from the inner
region. The possibility of a quasi-Keplerian disc is seen and these results can explain the observed spin
variations in MSPs like SAX J1808.4-3658 and XTE J1814-338. |
| format | Article |
| id | oai:idr.kab.ac.ug:20.500.12493-463 |
| institution | KAB-DR |
| language | en_US |
| publishDate | 2020 |
| publisher | Indian Academy of Sciences |
| record_format | dspace |
| spelling | oai:idr.kab.ac.ug:20.500.12493-4632024-01-17T04:50:48Z On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars Isaac, Habumugisha Solomon, B. Tessema Edward, Jurua Simon, K. Anguma 97.80.Jp X-ray binaries—97.60.Gb pulsars—97.10.Gz accretion and accretion discs In this study, we investigated the time-independent dynamics (disc structure, forces and torques) of a quasi-Keplerian disc around a millisecond pulsar (MSP) with an internal dynamo. We considered the disc around a MSP to be divided into the inner, middle and outer regions. By assuming that the disc matter flows in a quasi-Keplerian motion, we derived analytical equations for a complete structure (temperature, pressure, surface density, optical depth and magnetic field) of a quasi-Keplerian thin accretion disc, and the pressure gradient force (PGF). In our model, the MSP-disc interaction results into magnetic and material torques, such that for a given dynamo ( ) and quasi-Keplerian (n) parameter, we obtained enhanced spin-up and spin-down torques for a chosen star spin period. Results obtained reveal that PGF results into episodic torque reversals that contribute to spinning-up or spinning-down of a neutron star, mainly from the inner region. The possibility of a quasi-Keplerian disc is seen and these results can explain the observed spin variations in MSPs like SAX J1808.4-3658 and XTE J1814-338. Kabale University 2020-11-17T16:39:15Z 2020-11-17T16:39:15Z 2020 Article http://hdl.handle.net/20.500.12493/463 en_US application/pdf Indian Academy of Sciences |
| spellingShingle | 97.80.Jp X-ray binaries—97.60.Gb pulsars—97.10.Gz accretion and accretion discs Isaac, Habumugisha Solomon, B. Tessema Edward, Jurua Simon, K. Anguma On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title | On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title_full | On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title_fullStr | On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title_full_unstemmed | On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title_short | On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars |
| title_sort | on the structure of quasi keplerian accretion discs surrounding millisecond x ray pulsars |
| topic | 97.80.Jp X-ray binaries—97.60.Gb pulsars—97.10.Gz accretion and accretion discs |
| url | http://hdl.handle.net/20.500.12493/463 |
| work_keys_str_mv | AT isaachabumugisha onthestructureofquasikeplerianaccretiondiscssurroundingmillisecondxraypulsars AT solomonbtessema onthestructureofquasikeplerianaccretiondiscssurroundingmillisecondxraypulsars AT edwardjurua onthestructureofquasikeplerianaccretiondiscssurroundingmillisecondxraypulsars AT simonkanguma onthestructureofquasikeplerianaccretiondiscssurroundingmillisecondxraypulsars |