INTEGRAL/RossiXTE high-energy observation of a state transition of GX 339-4
(2006)
A link between radio loudness and X-ray/optical properties of AGN
International Conference Recent Advances in Natural Language Processing, RANLP (2006)
Abstract:
We have found empirically that the radio loudness of AGN can be understood as function of both the X-ray and optical luminosity. This way of considering the radio loudness was inspired by the hardness-intensity diagrams for X-ray binaries, in which objects follow a definite track with changes to their radio properties occurring in certain regions. We generalize the hardness-intensity diagram to a disk-fraction luminosity diagram, which can be used to classify the accretion states both of X-ray binaries and of AGN. Using a sample of nearly 5000 SDSS quasars with ROSAT matches, we show that an AGN is more likely to have a high radio: optical flux ratio when it has a high total luminosity or a large contribution from X-rays. Thus, it is necessary to take into account both the optical and the X-ray properties of quasars in order to understand their radio loudness. The success of categorizing quasars in the same way as X-ray binaries is further evidence for the unification of accretion onto stellar-mass and supermassive compact objects.Monitoring LMXBs with the faulkes telescope
International Conference Recent Advances in Natural Language Processing, RANLP (2006)
Abstract:
The Faulkes Telescope Project is the educational arm of the Las Cumbres Observatory Global Telescope Network (LCOGT). It currently has two 2-metre robotic telescopes, located at Haleakala on Maui (FT North) and Siding Spring in Australia (FT South). It is planned to increase this to six 2-metre telescopes in the future, complemented by a network of 30-40 smaller (0.4 - 1 metre) telescopes providing 24 hour coverage of both northern and southern hemispheres. We are undertaking a monitoring project of 10 low-mass X-ray binaries (LMXBs) using FT North to study the optical continuum behaviour of X-ray transients in quiescence. The introduction of FT South in September 2006 allows us to extend this monitoring to include 17 southern hemisphere LMXBs. With new instrumentation, we also intend to expand this monitoring to include both infrared wavelengths and spectroscopy.Astrophysics and space science: From X-ray binaries to quasars: Black holes on all mass scales
, 2005
Abstract:
This volume brings together contributions from many of the world's leading authorities on black hole accretion. The papers within represent part of a new movement to make use of the relative advantages of studying stellar mass and supermassive black holes, and to bring together the knowledge gained from the two approaches. The topics discussed include observational and theoretical work-variability, spectroscopy, disk-jet connections, and multi-wavelength campaigns on black holes. © Springer 2005. All Rights Reserved.The Growth, Polarization, and Motion of the Radio Afterglow from the Giant Flare from SGR 1806–20
The Astrophysical Journal American Astronomical Society 634:1 (2005) l93-l96