C. Phillips

The 6-GHz methanol multibeam maser catalogue - I. Galactic Centre region, longitudes 345° to 6°

Original article can be found at: http://www3.interscience.wiley.com/journal/ Copyright Royal Astronomical Society

The 6-GHz multibeam maser survey – I. Techniques

A new 7-beam 6 7 GHz receiver has been built to survey the Galaxy and the Magellanic Clouds for newly forming high-mass stars that are pinpointed by strong methanol maser emission at 6668 MHz. The receiver was jointly constructed by Jodrell Bank Observatory (JBO) and the Australia Telescope National Facility (ATNF) and allows simultaneous coverage at 6668 and 6035 MHz. It was successfully commissioned at Parkes in January 2006 and is now being used to conduct the Parkes-Jodrell multibeam maser survey of the Milky Way. This will be the first systematic survey of the entire Galactic plane for masers of not only 6668-MHz methanol, but also 6035-MHz excited-state hydroxyl. The survey is two orders of magnitude faster than most previous systematic surveys and has an rms noise level of �0.17Jy. This paper describes the observational strategy, techniques and reduction procedures of the Galactic and Magellanic Cloud surveys, together with deeper, pointed, follow-up observations and complementary observations with other instruments. It also includes an estimate of the survey detection efficiency. The 111 days of observationswith the Parkes telescope have so far yielded >800 methanol sources, of which �350 are new discoveries. The whole project will provide the first comprehensive Galaxy-wide catalogue of 6668-MHz and 6035-MHz masers.

Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event

The IceCube neutrino telescope in the South Pole has observed several high-energy neutrinos of undetermined origin. Could the third detected PeV event be from blazar PKS B1424–418?

Multibeam maser survey of methanol and excited OH in the Magellanic Clouds: new detections and maser abundance estimates

We present the results of the first complete survey of the Large (LMC) and Small (SMC) Magellanic Clouds for 6668-MHz methanol and 6035-MHz excited-state hydroxyl masers. In addition to the survey, higher sensitivity targeted searches towards known star formation regions were conducted. The observations yielded the discovery of a fourth 6668-MHz methanol maser in the LMC, found towards the star-forming region N160a, and a second 6035-MHz excited-state hydroxyl maser, found towards N157a. We have also re-observed the three previously known 6668-MHz methanol masers and the single 6035-MHz hydroxyl maser. We failed to detect emission from either transition in the SMC. All observations were initially made using the Methanol Multibeam (MMB) survey receiver on the 64-m Parkes telescope as part of the MMB project and accurate positions have been measured with the Australia Telescope Compact Array. We compare the maser populations in the Magellanic Clouds with those of our Galaxy and discuss their implications for the relative rates of massive star formation, heavy metal abundance and the abundance of complex molecules. The LMC maser populations are demonstrated to be smaller than their Milky Way counterparts. Methanol masers are underabundant by a factor of ∼45, whilst hydroxyl and water masers are a factor of ∼10 less abundant than our Galaxy.

LUNASKA experiment observational limits on UHE neutrinos from Centaurus A and the Galactic Centre

We present the first observational limits to the ultra-high-energy (UHE) neutrino flux from the Galactic Centre, and from Centaurus A which is the nearest active galactic nucleus. These results are based on our ‘Lunar UHE Neutrino Astrophysics using the Square Kilometre Array’ (LUNASKA) project experiments at the Australia Telescope Compact Array (ATCA). We also derive limits for the previous experiments and compare these limits with expectations for acceleration and superheavy dark matter models of the origin of UHE cosmic rays.

FIRST PARALLAX MEASUREMENTS TOWARD A 6.7 GHz METHANOL MASER WITH THE AUSTRALIAN LONG BASELINE ARRAY—DISTANCE TO G 339.884−1.259.

We have conducted the first parallax and proper motion measurements of 6.7 GHz methanol maser emission using the Australian Long Baseline Array. The parallax of G 339.884-1.259 measured from five epochs of observations is 0.48 +/- 0.08 mas, corresponding to a distance of 2.1(-0.3)(+0.4) kpc, placing it in the Scutum spiral arm. This is consistent (within the combined uncertainty) with the kinematic distance estimate for this source at 2.5 +/- 0.5 kpc using the latest Solar and Galactic rotation parameters. We find from the Lyman continuum photon flux that the embedded core of the young star is of spectral type B1, demonstrating that luminous 6.7 GHz methanol masers can be associated with high-mass stars toward the lower end of the mass range.

Parkes full polarization spectra of OH masers – I. Galactic longitudes 350° through the Galactic Centre to 41°

Full polarization measurements of 1665 and 1667-MHz OH masers at sites of massive star formation have been made with the Parkes 64-m radio telescope. Here we present the resulting spectra for 104 northerly sources. For more than 20 masers we made new measurements with the ATCA (which also revealed several hitherto unreported masers), in most cases yielding arcsecond precision to match the majority of sites. Position improvements assist in distinguishing OH masers with accompanying methanol masers from those without (thought to be at a later stage of evolution). There was no existing linear polarization information at many sites, and spectral resolution was sometimes poor, or velocity coverage incomplete. These inadequacies are addressed by the present Parkes spectra. The whole OH maser sample exhibit the well-known predominance of highly circularly polarized features. We find that linear polarization is also common, but usually much weaker, and we highlight the rare cases of very pronounced linear polarization that can extend to 100 per cent. Unusually large velocity ranges of at least 25 km/s are present at seven sites. Our spectra measurements for most sources are at two epochs spaced by nearly one year, and reveal high stability at most sites, and marked variability (more than factors of two in the strongest feature) at only five sites. The spectra also provide a valuable reference for longer term variability, with high stability evident over the past decades at 10 sites and marked variability for four of the sample. Future systematic monitoring of these variables may uncover further examples of periodicity, a phenomenon so far recognised in only one source.

Parallaxes of 6.7-GHz methanol masers towards the G 305.2 high-mass star formation region

We have made measurements to determine the parallax and proper motion of the three 6.7-GHz methanol masers G 305.200+0.019, G 305.202+0.208 and G 305.208+0.206. The combined parallax is found to be 0.25±0.05 mas, corresponding to a distance of 4.1^{+1.2}_{-0.7} kpc. This places the G 305.2 star formation region in the Carina-Sagittarius spiral arm. The inclusion of G 305.2 increases the Galactic azimuth range of the sources in this arm by 40° from Sato et al., allowing us to determine the pitch angle of this spiral with greater confidence to be ψ = 19.0° ± 2.6°. The first very long baseline interferometry spot maps of the 6.7-GHz methanol masers towards these sources show that they have simple linear and ring-like structures, consistent with emission expected from class II methanol masers in general.

H i emission and absorption in nearby, gas-rich galaxies – II. Sample completion and detection of intervening absorption in NGC 5156

We present the results of a survey for intervening 21cm HI absorption in a sample of 10 nearby, gas-rich galaxies selected from the HI Parkes All-Sky Survey (HIPASS). This follows the six HIPASS galaxies searched in previous work and completes our full sample. In this paper we searched for absorption along 17 sightlines with impact parameters between 6 and 46 kpc, making one new detection. We also obtained simultaneous HI emission-line data, allowing us to directly relate the absorption-line detection rate to the HI distribution. From this we find the majority of the non-detections in the current sample are because sightline does not intersect the HI disc of the galaxy at sufficiently high column density, but that source structure is also an important factor. The detected absorption-line arises in the galaxy NGC 5156 (

Parkes full polarization spectra of OH masers – II. Galactic longitudes 240° to 350°

z = 0.01