Browsing by Author "Coriat, M"

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    Accretion and outflow in black-hole x-ray binaries
    (2015) Dusoye, Avishek; Coriat, M; Woudt, Patrick Alan
    Black hole X-ray binaries (BHXBs) are stellar binary systems consisting of a black hole (BH) and a companion star. They are known to produce X-ray emission through the accretion of mass from the companion star onto the black hole via an accretion disc, as well as radio emission originating from their jets. My thesis splits into two projects. On one hand, I focus on the connection between the X-ray emitting accretion disc and the radio jets of BHXBs in general, by studying the quasi-simultaneous evolution of the radio fluxes and the X-ray fluxes from 17 BHXBs. This connection, also known as the radio/X-ray correlation has been studied and updated over the past years. New observations of new and known sources have shown that another population of X-ray binaries exists (referred to as outliers), lying below the standard radio/X-ray correlation. I investigate whether the mass of the black hole component of BHXBs can explain the existence of these outliers. In my second project, I focus on an exotic source, known as SS433. It has a supercritical accretion disc and displays precessing relativistic jets. I investigate whether these jets are made up of proton-electron plasma or electron-positron plasma. Circular polarization (CP) is a good diagnostics for understanding the particle composition of radio jets. Therefore we have observed the circular polarized flux densities of SS433 using the Australia Telescope Compact Array (ATCA) for a broad range of frequencies between 1:4 - 10 GHz. From those observations, a CP spectrum can be constructed and the spectral index can be estimated. There are 4 ways of producing CP emission and the spectral index helps us to constrain the CP production mechanism. In addition, the kinematics of propelling a proton-electron plasma in a jet is different from that of electronpositron plasma. I simulate various plausible models for the energy content of the jets and thereby aim to constrain the particle composition of the jets. Black hole X-ray binaries (BHXBs) are stellar binary systems consisting of a black hole (BH) and a companion star. They are known to produce X-ray emission through the accretion of mass from the companion star onto the black hole via an accretion disc, as well as radio emission originating from their jets. My thesis splits into two projects. On one hand, I focus on the connection between the X-ray emitting accretion disc and the radio jets of BHXBs in general, by studying the quasi-simultaneous evolution of the radio fluxes and the X-ray fluxes from 17 BHXBs. This connection, also known as the radio/X-ray correlation has been studied and updated over the past years. New observations of new and known sources have shown that another population of X-ray binaries exists (referred to as outliers), lying below the standard radio/X-ray correlation. I investigate whether the mass of the black hole component of BHXBs can explain the existence of these outliers. In my second project, I focus on an exotic source, known as SS433. It has a supercritical accretion disc and displays precessing relativistic jets. I investigate whether these jets are made up of proton-electron plasma or electron-positron plasma. Circular polarization (CP) is a good diagnostics for understanding the particle composition of radio jets. Therefore we have observed the circular polarized flux densities of SS433 using the Australia Telescope Compact Array (ATCA) for a broad range of frequencies between 1:4 - 10 GHz. From those observations, a CP spectrum can be constructed and the spectral index can be estimated. There are 4 ways of producing CP emission and the spectral index helps us to constrain the CP production mechanism. In addition, the kinematics of propelling a proton-electron plasma in a jet is different from that of electron-positron plasma. I simulate various plausible models for the energy content of the jets and thereby aim to constrain the particle composition of the jets.
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    Open Access
    Radio monitoring of the hard state jets in the 2011 outburst of MAXI J1836−194
    (2015) Russell, T D; Miller-Jones, J C A; Curran, P A; Soria, R; Altamirano, D; Corbel, S; Coriat, M; Moin, A; Russell, D M; Sivakoff, G R; Slaven-Blair, T J; Belloni, T M; Fender, R P; Heinz, S; Jonker, P G; Krimm, H A; Körding, E G; Maitra, D; Markoff, S; Middleton, M; Migliari, S; Remillard, R A; Rupen, M P; Sarazin, C L; Tetarenko, A J; Torres, M A P; Tudose, V; Tzioumis, A K
    MAXI J1836-194 is a Galactic black hole candidate X-ray binary that was discovered in 2011 when it went into outburst. In this paper, we present the full radio monitoring of this system during its 'failed' outburst, in which the source did not complete a full set of state changes, only transitioning as far as the hard intermediate state. Observations with the Karl G. Jansky Very Large Array (VLA) and Australia Telescope Compact Array (ATCA) show that the jet properties changed significantly during the outburst. The VLA observations detected linearly polarised emission at a level of ~1% early in the outburst, increasing to ~3% as the outburst peaked. High-resolution images with the Very Long Baseline Array (VLBA) show a ~15 mas jet along the position angle -21 ± 2o, in agreement with the electric vector position angle found from our polarisation results (-21 ± 4o), implying that the magnetic field is perpendicular to the jet. Astrometric observations suggest that the system required an asymmetric natal kick to explain its observed space velocity. Comparing quasi-simultaneous X-ray monitoring with the 5 GHz VLA observations from the 2011 outburst shows an unusually steep hard-state radio/X-ray correlation of LR ∝ LX1.8±0.2, where LR and LX denote the radio and X-ray luminosities, respectively. With ATCA and Swift monitoring of the source during a period of re-brightening in 2012, we show that the system lay on the same steep correlation. Due to the low inclination of this system, we then investigate the possibility that the observed correlation may have been steepened by variable Doppler boosting.