Pulsars, transients and relativistic astrophysics

Abstract:

We present an internal shocks model to investigate particle acceleration and radiation production in microquasar jets. The jet is modelled with discrete ejecta at various time intervals. These ejecta (or 'shells') may have different properties including the bulk velocity. Faster shells can catch up and collide with the slower ones, thus giving rise to shocks. The particles are accelerated inside the shocked plasma. Each collision results in a new shell, which may take part in any subsequent collisions as well as radiate due to synchrotron radiation. Almost continuous energy dissipation along the jet can be obtained with a large number of shell collisions. We investigate the spectral energy distribution of such jets as well as the physical significance of various parameters (e.g. the time interval between ejections and the shell size). © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

Abstract:

The Faulkes Telescope Project is an educational and research arm of the Las Cumbres Observatory Global Telescope Network (LCOGTN). It has two 2-metre robotic telescopes, located at Haleakala on Maui (FT North) and Siding Spring in Australia (FT South). It is planned for these telescopes to be complemented by a research network of eighteen 1-metre telescopes, along with an educational network of twenty-eight 0.4-metre telescopes, providing 24 hour coverage of both northern and southern hemispheres. We have been conducting a monitoring project of 13 low-mass X-ray binaries (LMXBs) using FT North since early 2006. The introduction of FT South has allowed us to extend this to monitor a total of 30 LMXBs (see target list, Section 4). New instrumentation will allow us to expand this project to include both infrared wavelengths (z and y band) and spectroscopy. Brighter targets (∼ 16 - 18 mag.) are imaged weekly in V, R and i' bands (SNR ∼ 50), while fainter ones (> 18 mag.) are observed only in i' band (SNR ∼ 20). We alter this cadence in response to our own analysis or Astronomers Telegrams (ATels). © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

Abstract:

We present a multiwavelength analysis of the outbursts from the neutron star X-ray binary Aql X-1. We focus on three outbursts for which quasi-simultaneous data in radio, optical and Xray bands exist. We find evidence that the disc/jet coupling in Aql X-1 is similar to the one documented for black hole X-ray binaries, at least from the point of view of the general behaviour revealed during outbursts. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

Abstract:

The GlobalJetWatch project (www.globaljetwatch.net) will place small (0.5-metre) commerical telescopes in four schools around the world. Each telescope will be equipped with a custom designed spectrograph, currently being built by the Astrophysics sub-department of the University of Oxford. The scientific goal of the project is to provide continual monitoring of a rosetta stone object, the micro-quasar SS433. In addition,the project has a significant out-reach element, aiming to involve school children on four-continents in front-line astronomical research. The spectrograph is a fibre-fed fixed format cross-dispersed echellete design providing R 6000 spectra from 4300-8500Å in a single exposure. The spectrograph is built almost entirely from off-the-shelf components. The four GlobalJetWatch sites (Australia, India, South Africa,Chile) will be commissioned in 2008/09. Here we present the baseline design of the spectrograph, and initial results from the prototype on-sky commissioning in Oxford.