Richard W Hunstead

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Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of(More)
Jupiter's nonthermal microwave emission, as measured by a global network of 11 radio telescopes, increased dramatically during the Shoemaker-Levy 9 impacts. The increase was wavelength-dependent, varying from approximately 10 percent at 70 to 90 centimeters to approximately 45 percent at 6 and 36 centimeters. The radio spectrum hardened (flattened toward(More)
We present an alternative interpretation of the observations of BR 1202−0725 at z = 4.695 and show that its properties are consistent with a relativistic jet, issuing from the quasar core, propagating into the inter-galactic medium and triggering star formation along its path. Prompted by this finding, we reviewed all the z > 3 objects detected in molecular(More)
We report new observations of Zn II and Cr II absorption lines in 10 damped Lyman α systems (DLAs), mostly at redshift z abs > ∼ 2.5. By combining these results with those from our earlier survey (Pettini et al. 1994) and other recent data, we construct a sample of 34 measurements (or upper limits) of the Zn abundance relative to hydrogen [Zn/H]; the sample(More)
We have observed the black hole candidate X-ray binary GX 339-4 at radio wavelengths before, during and after the 1998 high/soft X-ray state transition. We find that the radio emission from the system is strongly correlated with the hard X-ray emission and is reduced by a factor ≥ 25 during the high/soft state compared to the more usual low/hard state. At(More)
This paper is the second in a series describing the Sydney University Molonglo Sky Survey (SUMSS) being carried out at 843 MHz with the Molonglo Observatory Synthesis Telescope (MOST). The survey will consist of ∼ 590 4.3 • × 4.3 • mosaic images with 45 ′′ ×45 ′′ cosec|δ| resolution, and a source catalogue. In this paper we describe the initial release(More)
Subject headings: Black hole physics – relativity – stars: binaries (GX 339−4) – physical data and processes: accretion disks ABSTRACT We present the first results of coordinated multi-wavelength observations of the Galactic black hole GX 339−4 in a canonical low–hard state, obtained during its 2004 outburst. XMM-Newton observed the source for 2 revolutions(More)
This is the third in a series of papers that present observations and results for a sample of 76 ultra-steep-spectrum radio sources designed to find galaxies at high redshift. Here we present multi-frequency radio observations, from the Australia Telescope Compact Array, for a subset of 37 galaxies from the sample. Matched resolution observations at 2.3,(More)
This paper introduces a new program to find high-redshift radio galaxies in the southern hemisphere through ultra-steep spectrum (USS) selection. We define a sample of 234 USS radio sources with spectral indices α 843 408 ≤ −1.0 (S ν ∝ ν α) and flux densities S 408 ≥ 200 mJy in a region of 0.35 sr, chosen by cross-correlating the revised 408 MHz Molonglo(More)
We present a comparison of the properties of a giant radio galaxy and the ambient intergalactic medium, whose properties are inferred from the large-scale distribution in galaxies. The double lobes of the radio galaxy MSH 05−22 are giant—1.8 Mpc projected linear size—and interacting with the environment outside the interstellar medium and coronal halo(More)