{"id":{"repo_id":"soton","oai_identifier":"oai:eprints.soton.ac.uk:161189"},"canonical_url":"https://search.dev.ndltd.org/etd/soton/oai:eprints.soton.ac.uk:161189","repository":{"repo_id":"soton","name":"University of Southampton","base_url":"https://eprints.soton.ac.uk/cgi/oai2"},"display":{"title":"A theoretical study of relativistic jets and accretion processes","abstract":"The following work explores different aspects of the disc:jet connection in X-ray binaries. There is a detailed description of a new jet model (iShocks) that is used, firstly, to address the re-energization problem in the conical jet geometries. The adiabatic energy losses suffered by conical jets are successfully countered to reproduce the canonical flat/inverted synchrotron spectrum associated with compact radio jets.
The iShocks model uses discrete packets of plasma, or shells, to simulate a jet. The shell collisions give rise to the shocks that are used to re-energize the emitting electrons. Multiple internal shocks, all along the jet, are shown to be necessary to achieve sufficient re-acceleration. The flat/inverted spectrum (ranging from the infra-red to the radio) is successfully reproduced and the high frequency break for such a spectrum is shown to be correlated with the jet power: vb ~ L0.6W. While the flat-spectrum synchrotron flux is also correlated with the jet power via: Fv ~ L1.4W. Both these correlations are in agreement with the previous analytical predictions. The model is also used to explore themassive ejections scenario in the source GRS 1915+105. Various iShocks set-ups are used to model the data that display the flaring behaviour observed in different frequencies (IR-mm-radio).
The X-ray binary timing properties are also investigated with the aide of the iShocks model. In particular, the optical/X-ray correlations are the focus of the present study. These correlations have been observed to show some interesting behaviours, such as: the optical lagging the X-rays, and the optical emission showing awareness of the X-ray emission in the form of pre-cognition dips. A number of these correlations are successfully reproduced by translating the simulated X-ray light curves into the jet parameters used as the input for the iShocks model.
In addition to relativistic jets, a study of the electron-positron pair processes is also included in the present work. The electron-positron pair annihilation is implemented in an existing Comptonization code (simulating the corona) to explore the possibility of masking an annihilation line from the X-ray binary sources. The results show that radiative processes such as inverse Compton scattering and bremsstrahlung radiation, in addition to thermal line broadening, can be very effective in making the e-/e+ annihilation line indistinguishable from the rest of the high energy spectrum.","abstract_html":"The following work explores different aspects of the disc:jet connection in X-ray binaries. There is a detailed description of a new jet model (iShocks) that is used, firstly, to address the re-energization problem in the conical jet geometries. The adiabatic energy losses suffered by conical jets are successfully countered to reproduce the canonical flat/inverted synchrotron spectrum associated with compact radio jets.<br/><br/>The iShocks model uses discrete packets of plasma, or shells, to simulate a jet. The shell collisions give rise to the shocks that are used to re-energize the emitting electrons. Multiple internal shocks, all along the jet, are shown to be necessary to achieve sufficient re-acceleration. The flat/inverted spectrum (ranging from the infra-red to the radio) is successfully reproduced and the high frequency break for such a spectrum is shown to be correlated with the jet power: v<sub>b</sub> ~ L<sup>0.6</sup><sub>W</sub>. While the flat-spectrum synchrotron flux is also correlated with the jet power via: F<sub>v</sub> ~ L<sup>1.4</sup><sub>W</sub>. Both these correlations are in agreement with the previous analytical predictions. The model is also used to explore themassive ejections scenario in the source GRS 1915+105. Various iShocks set-ups are used to model the data that display the flaring behaviour observed in different frequencies (IR-mm-radio).<br/><br/>The X-ray binary timing properties are also investigated with the aide of the iShocks model. In particular, the optical/X-ray correlations are the focus of the present study. These correlations have been observed to show some interesting behaviours, such as: the optical lagging the X-rays, and the optical emission showing awareness of the X-ray emission in the form of pre-cognition dips. A number of these correlations are successfully reproduced by translating the simulated X-ray light curves into the jet parameters used as the input for the iShocks model.<br/><br/>In addition to relativistic jets, a study of the electron-positron pair processes is also included in the present work. The electron-positron pair annihilation is implemented in an existing Comptonization code (simulating the corona) to explore the possibility of masking an annihilation line from the X-ray binary sources. The results show that radiative processes such as inverse Compton scattering and bremsstrahlung radiation, in addition to thermal line broadening, can be very effective in making the e<sup>-</sup>/e<sup>+</sup> annihilation line indistinguishable from the rest of the high energy spectrum.","abstract_has_math":false,"creators":["Jamil, Omar"],"institution":"University of Southampton","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Fender, Rob"],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-02","date_published":"2010-02","updated_at":"2026-07-24T04:36:14Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Fender, Rob"]},{"key":"dc:creator","label":"Author","values":["Jamil, Omar"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-02-23"]},{"key":"dc:date.issued","label":"Date","values":["2010-02"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Physics & Astronomy (pre 2011 reorg)","School of Physics and Astronomy"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Southampton"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.soton.ac.uk/161189/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.soton.ac.uk/161189/1/Omar_Jamil_thesis.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The following work explores different aspects of the disc:jet connection in X-ray binaries. There is a detailed description of a new jet model (iShocks) that is used, firstly, to address the re-energization problem in the conical jet geometries. The adiabatic energy losses suffered by conical jets are successfully countered to reproduce the canonical flat/inverted synchrotron spectrum associated with compact radio jets.
The iShocks model uses discrete packets of plasma, or shells, to simulate a jet. The shell collisions give rise to the shocks that are used to re-energize the emitting electrons. Multiple internal shocks, all along the jet, are shown to be necessary to achieve sufficient re-acceleration. The flat/inverted spectrum (ranging from the infra-red to the radio) is successfully reproduced and the high frequency break for such a spectrum is shown to be correlated with the jet power: vb ~ L0.6W. While the flat-spectrum synchrotron flux is also correlated with the jet power via: Fv ~ L1.4W. Both these correlations are in agreement with the previous analytical predictions. The model is also used to explore themassive ejections scenario in the source GRS 1915+105. Various iShocks set-ups are used to model the data that display the flaring behaviour observed in different frequencies (IR-mm-radio).
The X-ray binary timing properties are also investigated with the aide of the iShocks model. In particular, the optical/X-ray correlations are the focus of the present study. These correlations have been observed to show some interesting behaviours, such as: the optical lagging the X-rays, and the optical emission showing awareness of the X-ray emission in the form of pre-cognition dips. A number of these correlations are successfully reproduced by translating the simulated X-ray light curves into the jet parameters used as the input for the iShocks model.
In addition to relativistic jets, a study of the electron-positron pair processes is also included in the present work. The electron-positron pair annihilation is implemented in an existing Comptonization code (simulating the corona) to explore the possibility of masking an annihilation line from the X-ray binary sources. The results show that radiative processes such as inverse Compton scattering and bremsstrahlung radiation, in addition to thermal line broadening, can be very effective in making the e-/e+ annihilation line indistinguishable from the rest of the high energy spectrum."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["A theoretical study of relativistic jets and accretion processes"]}]}],"canonical_facts":{"dc:contributor.advisor":["Fender, Rob"],"dc:creator":["Jamil, Omar"],"dc:date":["2010-02-23"],"dc:date.issued":["2010-02"],"dc:description.abstract":["The following work explores different aspects of the disc:jet connection in X-ray binaries. There is a detailed description of a new jet model (iShocks) that is used, firstly, to address the re-energization problem in the conical jet geometries. The adiabatic energy losses suffered by conical jets are successfully countered to reproduce the canonical flat/inverted synchrotron spectrum associated with compact radio jets.
The iShocks model uses discrete packets of plasma, or shells, to simulate a jet. The shell collisions give rise to the shocks that are used to re-energize the emitting electrons. Multiple internal shocks, all along the jet, are shown to be necessary to achieve sufficient re-acceleration. The flat/inverted spectrum (ranging from the infra-red to the radio) is successfully reproduced and the high frequency break for such a spectrum is shown to be correlated with the jet power: vb ~ L0.6W. While the flat-spectrum synchrotron flux is also correlated with the jet power via: Fv ~ L1.4W. Both these correlations are in agreement with the previous analytical predictions. The model is also used to explore themassive ejections scenario in the source GRS 1915+105. Various iShocks set-ups are used to model the data that display the flaring behaviour observed in different frequencies (IR-mm-radio).
The X-ray binary timing properties are also investigated with the aide of the iShocks model. In particular, the optical/X-ray correlations are the focus of the present study. These correlations have been observed to show some interesting behaviours, such as: the optical lagging the X-rays, and the optical emission showing awareness of the X-ray emission in the form of pre-cognition dips. A number of these correlations are successfully reproduced by translating the simulated X-ray light curves into the jet parameters used as the input for the iShocks model.
In addition to relativistic jets, a study of the electron-positron pair processes is also included in the present work. The electron-positron pair annihilation is implemented in an existing Comptonization code (simulating the corona) to explore the possibility of masking an annihilation line from the X-ray binary sources. The results show that radiative processes such as inverse Compton scattering and bremsstrahlung radiation, in addition to thermal line broadening, can be very effective in making the e-/e+ annihilation line indistinguishable from the rest of the high energy spectrum."],"dc:format":["text"],"dc:identifier.uri":["https://eprints.soton.ac.uk/161189/1/Omar_Jamil_thesis.pdf"],"dc:publisher.department":["Physics & Astronomy (pre 2011 reorg)","School of Physics and Astronomy"],"dc:publisher.institution":["University of Southampton"],"dc:relation.isreferencedby":["https://eprints.soton.ac.uk/161189/"],"dc:title":["A theoretical study of relativistic jets and accretion processes"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T04:36:14Z"}