Dr Maxim Voronkov (ATNF)

Masers and SKA: 2.5 years with ATNF - Dr Maxim Voronkov Colloquium

ATNF Marsfield Lecture Theatre

Abstract

The talk contains two largely unrelated parts devoted to my current
research activity in ATNF. The first part is related to the high
fidelity imaging problem and the Square Kilometre Array (SKA) simulations.
High dynamic range (the requirement is 10^6 at 1.4 GHz) is an important
requrement for the SKA. Having a wide field of view and operating at
relatively low frequencies this instrument should be able to detect a
weak source in the presence of a number of strong sources.
The dynamic range provided by an interferometric array is limited by the
software used for data processing. I will show the weaknesses of the
Cotton-Schwab clean algorithm and discuss some possible remedies.

The second part of the colloquium concerns the methanol masers.
Theoretical investigations inspired by the ATCA observations of OMC-1
predict a low temperature (about 60K) pumping regime of the 6.7 GHz
methanol masers. In this regime the 6.7 GHz masers (class II - radiative
pumping) may appear simultaneously with some class I masers (collisional
pumping), e.g. that at 25 GHz. It is in contrast to the widespread opinion
that such coexistence is impossible. The ATCA observations revealed a maser
feature at -1.1 km/s, where no methanol emission has been previously reported.
This maser became one of the best known examples of the class II masers
associated with molecular outflows. I will also review the current status
of the various projects aimed at understanding the class I methanol masers.