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M. Sinclair

Publications and source records attributed to M. Sinclair.

2 recordsLinked to original sources
arXiv2003

A Survey for H2O Megamasers III. Monitoring Water Vapor Masers in Active Galaxies

We present single-dish monitoring of the spectra of 13 extragalactic water megamasers taken over a period of 9 years and a single epoch of sensitive spectra for 7 others. Our data include the first K-band science observations taken with the new 100 m Green Bank Telescope (GBT). In the context of a circumnuclear, molecular disk model, our results suggest that either (a) the maser lines seen are systemic features subject to a much smaller acceleration than present in NGC 4258, presumably because the gas is farther from the nuclear black hole, or (b) we are detecting ``satellite'' lines for which the acceleration is in the plane of the sky. We also report a search for water vapor masers towards the nuclei of 58 highly inclined, nearby galaxies.

astro-ph↗
arXiv2000

An Australia telescope survey for CMB anisotropies

We have surveyed six distinct `empty fields' using the Australia Telescope Compact Array in an ultra-compact configuration with the aim of imaging, with a high brightness sensitivity, any arcmin-scale brightness-temperature anisotropies in the background radio sky. The six well-separated regions were observed at a frequency of 8.7 GHz and the survey regions were limited by the ATCA primary beams which have a full width at half maximum of 6 arcmin at this frequency; all fields were observed with a resolution of 2 arcmin and an rms thermal noise of 24 microJy/beam. After subtracting foreground confusion detected in higher resolution images of the fields, residual fluctuations in Stokes I images are consistent with the expectations from thermal noise and weaker (unidentified) foreground sources; the Stokes Q and U images are consistent with expectations from thermal noise. Within the sensitivity of our observations, we have no reason to believe that there are any Sunyaev-Zeldovich holes in the microwave sky surveyed. Assuming Gaussian-form CMB anisotropy with a `flat' spectrum, we derive 95 per cent confidence upper limits of Q_flat < 10--11 microK in polarized intensity and Q_flat < 25 microK in total intensity. The ATCA filter function peaks at l=4700 and has half maximum values at l=3350 and 6050.

astro-ph↗