Publications (6)0 Total impact
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Article: The radio continuum structure of Centaurus A at 1.4 GHz
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ABSTRACT: A 45 deg2 radio continuum imaging campaign of the nearest radio galaxy, Centaurus A, is reported. Using the Australia Telescope Compact Array and the Parkes 64m radio telescope at 1.4 GHz, the spatial resolution of the resultant image is ~600 pc, resolving the ~500 kpc giant radio lobes with approximately five times better physical resolution compared to any previous image, and making this the most detailed radio continuum image of any radio galaxy to date. In this paper, we present these new data and discuss briefly some of the most interesting morphological features that we have discovered in the images... abstract truncated.04/2011; -
Article: Modeling the Magnetic Field in the Galactic Disk using New Rotation Measure Observations from the Very Large Array
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ABSTRACT: We have determined 194 Faraday rotation measures (RMs) of polarized extragalactic radio sources using new, multi-channel polarization observations at frequencies around 1.4 GHz from the Very Large Array (VLA) in the Galactic plane at $17^\circ \leq l \leq 63^\circ$ and $205^\circ \leq l \leq 253^\circ$. This catalog fills in gaps in the RM coverage of the Galactic plane between the Canadian Galactic Plane Survey and Southern Galactic Plane Survey. Using this catalog we have tested the validity of recently-proposed axisymmetric and bisymmetric models of the large-scale (or regular) Galactic magnetic field, and found that of the existing models we tested, an axisymmetric spiral model with reversals occurring in rings (as opposed to along spiral arms) best matched our observations. Building on this, we have performed our own modeling, using RMs from both extragalactic sources and pulsars. By developing independent models for the magnetic field in the outer and inner Galaxy, we conclude that in the inner Galaxy, the magnetic field closely follows the spiral arms, while in the outer Galaxy, the field is consistent with being purely azimuthal.Furthermore, the models contain no reversals in the outer Galaxy, and together seem to suggest the existence of a single reversed region that spirals out from the Galactic center. Comment: 18 pages, 12 figures, 2 tables; Accepted for publication in Astrophysical Journal (December 13, 2010)12/2010; -
Article: Parkes 300 to 900 MHz Rotation Measure Survey
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ABSTRACT: We propose two observing runs for the Parkes 300-900 MHz Rotation Measure Survey. This survey forms a key part of the Global Magneto-Ionic Medium Survey (GMIMS), a spectro-polarimetric survey of the diffuse polarized emission of the entire sky comprising six individual surveys. We ask for 28 nights in the forthcoming semester.ATNF Proposal. 03/2010; -1:2908. -
Article: HI Study of Southern Galactic Supernova Remnants
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ABSTRACT: We briefly summarize the survey of HI 21 cm emission lines to search for shocked atomic gas associated with Galactic supernova remnants (SNRs) in the southern sky. For G347.3-0.5, we discuss the distance to the SNR and the implications of the HI results.12/2003; -
Article: Radio polarization from the inner Galaxy at arcminute resolution
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ABSTRACT: The Southern Galactic Plane Survey (SGPS) is an HI and 1.4-GHz continuum survey of the 4th quadrant of the Galaxy at arcmin resolution. We present here results on linearly polarized continuum emission from an initial 28-square-degree Test Region for the SGPS, consisting of 190 mosaiced pointings of the Australia Telescope Compact Array, and covering the range 325.5 < l < 332.5, -0.5 < b < +3.5. Complicated extended structure is seen in linear polarization throughout the Test Region, almost all of which has no correlation with total intensity. We interpret the brightest regions of polarized emission as representing intrinsic structure in extended polarization, most likely originating in the Crux spiral arm at a distance of 3.5 kpc; fainter polarized structure is imposed by Faraday rotation in foreground material. Two large areas in the field are devoid of polarization. We argue that these voids are produced by foreground HII regions in which the magnetic field is disordered on scales of ~0.1-0.2 pc. We also identify a depolarized halo around the HII region RCW 94, which we suggest results from the interaction of the HII region with a surrounding molecular cloud. Comment: 21 pages, 5 embedded EPS figures, 9 jpeg figures, uses emulateapj apjfonts. Accepted to the Astrophysical Journal. Version with all 14 figures in embedded EPS format available at http://space.mit.edu/~bmg/sgps/10/2000; -
Article: The Southern Galactic Plane Survey
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ABSTRACT: . The Southern Galactic Plane Survey is a 21-cm line and continuum survey of the fourth quadrant of the Milky Way, covering the Galactic plane south of ffi = Gamma35 ffi . It is a combination of Parkes multibeam plus ATCA mosaiced interferometer data, thus it is sensitive to all angular scales from 2 0 to several degrees. The total number of ATCA fields is about 2200, which we intend to cover 40 times with 30 second snapshots at different hour angles and with different array configurations. The sensitivity will be about 60 mJy/beam rms in channels of 3.9 kHz (0.8 km/s), which translates to about 2.5 K rms brightness temperature. In the continuum we cover 128 MHz in all four Stokes parameters with rms noise of about 250 microJy/beam. The total area to be covered is 210 square degrees (Sigma1 ffi in latitude, 253 ffi to 358 ffi in longitude). We will cover a wider latitude range (Sigma10 ffi ) with Parkes alone. 1. Introduction The Southern Galactic Plane Survey is a pro...09/1999;
