2014-B, 128T

Authors: Prof. Slava Kitaeff (ICRAR/UWA), Dr. Anish Roshi (NRAO), Prof. John Dickey (U. Tasmania), Dr. Divya Oberoi (MIT/Haystack), Prof Lister Staveley-­‐Smith (ICRAR/UWA), Dr. Andrew Walsh (ICRAR/Curtin), Krystal Cook (UWA, student), Dr. Maria Cunningham (UNSW), Dr. A. R. Offringa (ANU), Dr. Paul Jones(UNSW)

Abstract: We propose to observe radio recombination line (RRLs) toward the star-forming complex NGC6334 and Galactic Centre with the MWA. The primary goal of the project is to detect the narrow spectral lines (less than 30 km/sec). We will develop a technique for accurate bandpass calibration that is critical for detection of weak spectral lines as the bandshape changes with pointing. We will also attempt to search for the molecular lines.

Authors: Dr. Tara Murphy (U. Sydney/CAASTRO), Dr. David Kaplan (UWMilwaukee), Dr. Martin Bell (CASS), Dr. Ramesh Bhat (Curtin/CAASTRO), Dr. Megan DeCesar (UW-Milwaukee), Dr. Paul Hancock (Curtin/CAASTRO), Dr. Emil Lenc (U. Sydney/CAASTRO), Cleo Loi (U. Sydney/CAASTRO), Dr. Andre Offringa (ANU/CAASTRO), Dr. Randall Wayth (Curtin/CAASTRO), Dr. Peter Williams (Harvard CfA)

Abstract: Magnetised extrasolar planets are expected to emit strongly at radio wavelengths, in the same way as magnetised planets in our own solar system. Emission is expected at low radio frequencies tied to the electron gyrofrequency. However, previous searches have all been negative. Any detection would directly constrain the magnetic field strength and geometry. In contrast, a number of ultracool dwarfs show steady and transient radio emission at cm wavelengths which is again directly related to the magnetic field geometry. Understanding the prevalence and properties of such emission will help explain the enhanced activity of ultra-cool dwarfs compared to other classes of stars.

Emission at metre wavelengths from these sources is expected to be faint, and the sensitivity of the MWA is limited by confusion. However, as the emission is tied to coherent magnetic structures it is expected to be up to 100% linearly polarized (this has been observed from some ultracool dwarfs). We can therefore take advantage of the much "darker" sky in circular polarization (Stokes V) to conduct a deep search for emission from exoplanets and ultracool dwarfs. This also has the potential to study other source classes: our work with the Radio Sky Monitor has already revealed several pulsars that we have detected in circular polarisation.

We propose to take advantage of the increased sensitivity that Stokes V brings to conduct a survey of two fields to search for highly circularly polarised sources. Both fields contain an exoplanet with predicted radio emission within the detectable range of MWA. There are also several pulsars and a number of ultracool dwarfs in each field. We will observe for a full night to cover a range of cadences, with repeated observations to ensure good coverage of the orbital period of our targets.