Pulsars, transients and relativistic astrophysics

Abstract:

The compelling evidence for a connection between SS 433 and W50 has provoked much imagination for decades. There are still many unanswered questions: What was the nature of the progenitor of the compact object in SS 433? What causes the evident re-collimation in SS 433's jets? How recent is SS 433's current precession state? What mass and energy contributions from a possible supernova explosion are required to produce W50? Here we comment on two of our 53 models: (i) featuring the SNR evolution alone, and (ii) the SNR combined with a simple jet model. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

Abstract:

A succession of near-IR spectroscopic observations, taken nightly throughout an entire cycle of SS 433's orbit with UKIRT, reveal (i) the persistent signature of SS 433's accretion disc, having a rotation speed of ∼ 500 kms-1and (ii) confirms the presence of the circumbinary disc recently discovered at optical wavelengths by Blundell, Bowler & Schmidtobreick (2008) and (iii) detects a much faster outflow than has previously been measured from the disc wind. Our relatively high spectral resolution at these near-IR wavelengths has enabled us to deconstruct the different components, and their physical origins, that comprise the Brackett-γ line in this binary system. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

Abstract:

A succession of near-IR spectroscopic observations, taken nightly throughout an entire cycle of SS 433's orbit with UKIRT, reveal (i) the persistent signature of SS 433's accretion disc, having a rotation speed of ∼ 500 kms-1and (ii) confirms the presence of the circumbinary disc recently discovered at optical wavelengths by Blundell, Bowler & Schmidtobreick (2008) and (iii) detects a much faster outflow than has previously been measured from the disc wind. Our relatively high spectral resolution at these near-IR wavelengths has enabled us to deconstruct the different components, and their physical origins, that comprise the Brackett-γ line in this binary system. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

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:

We derive accretion rate functions (ARFs) and kinetic luminosity functions (KLFs) for jet-launching supermassive black holes. The accretion rate as well as the kinetic power of an active galaxy is estimated from the radio emission of the jet. For compact low-power jets, we use the core radio emission while the jet power of high-power radio-loud quasars is estimated using the extended low-frequency emission to avoid beaming effects. We find that at low luminosities the ARF derived from the radio emission is in agreement with the measured bolometric luminosity function (BLF) of active galactic nucleus (AGN), i.e. all low-luminosity AGN launch strong jets. We present a simple model, inspired by the analogy between X-ray binaries (XRBs) and AGN, that can reproduce both the measured ARF of jet-emitting sources as well as the BLF. The model suggests that the break in power-law slope of the BLF is due to the inefficient accretion of strongly sub-Eddington sources. As our accretion measure is based on the jet power it also allows us to calculate the KLF and therefore the total kinetic power injected by jets into the ambient medium. We compare this with the kinetic power output from supernova remnants (SNRs) and XRBs, and determine its cosmological evolution. © 2007 The Authors.