We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar ... more We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar Mkn 421, based on data obtained with the Rossi X-ray Timing Explorer (RXTE) satellite. The QPO is seen prominently in the ASM data (at least 15 cycles), due to the fact that it has had near-continuous sampling for more than a decade. The PCA data, where the sampling is not uniform and shows many large gaps, provide supporting evidence at lower significance. QPOs are an important observable in accretion disks, can be modulated by various orbital timescales, and may be generated by a number of mechanisms. They have been studied extensively in X-ray binaries, and should be present in active galactic nuclei (AGN) if they are governed by a common set of physical principles. In jetted sources, QPOs can probe jet-disk interactions or helical oscillations. This QPO previously has been claimed intermittently in X-ray, radio and gamma-ray data, but the continuous, 15-year extent (1996-2011) of the ASM observations (in which Mkn 421 is the brightest AGN observed) provides a unique window. The QPO appears present for nearly the entire extent of the ASM observations. We explore various physical origens and modulating mechanisms, particularly interpretations of the QPO as a result of disk-jet interactions, either due to an accretion disk limit cycle, jet instabilities or helical motions. Limit-cycle related oscillations would not interact with either Keplerian or Lense-Thirring modulated oscillations, however those associated with jet instabilities or helical motions in the jet would likely be modulated by Lense-Thirring precession.
We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar ... more We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar Mkn 421 based on data obtained with the Rossi X-ray Timing Explorer satellite. The QPO is seen prominently in the ASM data (at least 15 cycles) due to the fact that it has had near-continuous sampling for more than a decade. The PCA data, where the sampling is not uniform and shows many large gaps, provide supporting evidence at lower significance. The QPOs are an important observable in accretion disks, can be modulated by various orbital timescales, and may be generated by a number of mechanisms. They have been studied extensively in X-ray binaries and should be present in active galactic nuclei (AGN) if they are governed by a common set of physical principles. In jetted sources, QPOs can probe jet–disk interactions or helical oscillations. This QPO has previously been claimed intermittently in X-ray, radio, and gamma-ray data, but the continuous, 15 yr extent (1996–2011) of the ASM ob...
This work proposes a methodology for testing phenomenologically motivated emission processes that... more This work proposes a methodology for testing phenomenologically motivated emission processes that account for the flux and polarization distribution and global structure of the 230 GHz sources imaged by the Event Horizon Telescope (EHT): Messier (M)87* and Sagittarius (Sgr) A*. We introduce into general relativistic magnetohydrodynamic (GRMHD) simulations some novel models to bridge the largely uncertain mechanisms by which high-energy particles in jet/accretion flow/black hole (JAB) system plasmas attain billion-degree temperatures and emit synchrotron radiation. The “Observing” JAB Systems methodology then partitions the simulation to apply different parametric models to regions governed by different plasma physics—an advance over methods in which one parametrization is used over simulation regions spanning thousands of gravitational radii from the central supermassive black hole. We present several classes of viewing-angle-dependent morphologies and highlight signatures of piecew...
We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar ... more We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar Mkn 421, based on data obtained with the Rossi X-ray Timing Explorer (RXTE) satellite. The QPO is seen prominently in the ASM data (at least 15 cycles), due to the fact that it has had near-continuous sampling for more than a decade. The PCA data, where the sampling is not uniform and shows many large gaps, provide supporting evidence at lower significance. QPOs are an important observable in accretion disks, can be modulated by various orbital timescales, and may be generated by a number of mechanisms. They have been studied extensively in X-ray binaries, and should be present in active galactic nuclei (AGN) if they are governed by a common set of physical principles. In jetted sources, QPOs can probe jet-disk interactions or helical oscillations. This QPO previously has been claimed intermittently in X-ray, radio and gamma-ray data, but the continuous, 15-year extent (1996-2011) of the ASM observations (in which Mkn 421 is the brightest AGN observed) provides a unique window. The QPO appears present for nearly the entire extent of the ASM observations. We explore various physical origens and modulating mechanisms, particularly interpretations of the QPO as a result of disk-jet interactions, either due to an accretion disk limit cycle, jet instabilities or helical motions. Limit-cycle related oscillations would not interact with either Keplerian or Lense-Thirring modulated oscillations, however those associated with jet instabilities or helical motions in the jet would likely be modulated by Lense-Thirring precession.
We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar ... more We report a 325(−7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar Mkn 421 based on data obtained with the Rossi X-ray Timing Explorer satellite. The QPO is seen prominently in the ASM data (at least 15 cycles) due to the fact that it has had near-continuous sampling for more than a decade. The PCA data, where the sampling is not uniform and shows many large gaps, provide supporting evidence at lower significance. The QPOs are an important observable in accretion disks, can be modulated by various orbital timescales, and may be generated by a number of mechanisms. They have been studied extensively in X-ray binaries and should be present in active galactic nuclei (AGN) if they are governed by a common set of physical principles. In jetted sources, QPOs can probe jet–disk interactions or helical oscillations. This QPO has previously been claimed intermittently in X-ray, radio, and gamma-ray data, but the continuous, 15 yr extent (1996–2011) of the ASM ob...
This work proposes a methodology for testing phenomenologically motivated emission processes that... more This work proposes a methodology for testing phenomenologically motivated emission processes that account for the flux and polarization distribution and global structure of the 230 GHz sources imaged by the Event Horizon Telescope (EHT): Messier (M)87* and Sagittarius (Sgr) A*. We introduce into general relativistic magnetohydrodynamic (GRMHD) simulations some novel models to bridge the largely uncertain mechanisms by which high-energy particles in jet/accretion flow/black hole (JAB) system plasmas attain billion-degree temperatures and emit synchrotron radiation. The “Observing” JAB Systems methodology then partitions the simulation to apply different parametric models to regions governed by different plasma physics—an advance over methods in which one parametrization is used over simulation regions spanning thousands of gravitational radii from the central supermassive black hole. We present several classes of viewing-angle-dependent morphologies and highlight signatures of piecew...
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Papers by Lani Oramas