Learn More
Collimated relativistic outflows-also known as jets-are amongst the most energetic phenomena in the Universe. They are associated with supermassive black holes in distant active galactic nuclei, accreting stellar-mass black holes and neutron stars in binary systems and are believed to be responsible for gamma-ray bursts. The physics of these jets, however,(More)
We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric Hα emission line has been in evidence for the past twenty years, although the shape of the line has changed significantly. We present an eccentric (e ∼ 0.7–0.9) low(More)
In observations with the Australia Telescope Compact Array we have resolved the radio counterpart of the unusual X-ray binary Cir X-1 into an asymmetric extended structure on arcsecond scales. In order to quantify the asymmetry we have redetermined as accurately as possible both the optical and radio coordinates of the source. The extended emission can be(More)
We have examined X-ray and optical observations of two ultra-luminous X-ray sources, X7 and X10 in NGC4559, using XMM-Newton, Chandra and HST. The UV/X-ray luminosity of X7 exceeds 2.1 × 10 40 erg s −1 in the XMM-Newton observation, and that of X10 is > 1.3×10 40 erg s −1. X7 has both thermal and power-law spectral components, The characteristic temperature(More)
Episodic ejection of plasma blobs have been observed in many black hole systems. While steady, continuous jets are believed to be associated with large-scale open magnetic fields, what causes the episodic ejection of blobs remains unclear. Here by analogy with the coronal mass ejection on the Sun, we propose a magnetohydrodynamical model for episodic(More)
We have analyzed the kinematical parameters of Cir X-1 to constrain the nature of its companion star, the eccentricity of the binary and the pre-supernova parameter space. We argue that the companion is most likely to be a low-mass (< ∼ 2.0 M ⊙) unevolved star and that the eccentricity of the orbit is 0.94 ± 0.04. We have evaluated the dy-namical effects of(More)
One method of obtaining the mass of the white dwarf in magnetic CVs is through their hard X-ray spectra. However, previous mass estimates using this method give lower limits because the temperature of the plasma in the post-shock region (where the hard X-rays are emitted) is lower than the temperature of the shock itself. In AM Her systems, the additional(More)
We have identified 127 discrete sources in a Chandra ACIS observation of M 83, with a detection limit of ≈ 3 × 10 36 erg s −1 in the 0.3–8.0 keV band. We discuss the individual X-ray spectral and time-variability properties of ≈ 20 bright sources with luminosities > ∼ 10 38 erg s −1 , and the statistical properties of the whole sample. About one third of(More)