Federation Fellowship symposium
Astronomers from near and far converged on Mt. Stromlo Observatory on 22 and 23 November to hear talks by Australian astronomy's three ARC Federation Fellows (Michael Dopita, Ron Ekers, and Dick Manchester), two of whom are affiliated with ATNF. The wide-ranging program also included 14 talks by researchers working in extragalactic astronomy, pulsar timing and gravitational waves. As the symposium was combined with the 9th annual Charlene Heisler workshop, topics related to starburst and active galaxies featured prominently in the program. Rather than try to summarise all of the talks here, or run the risk of omitting someone's favourite, this article just covers the three Federation Fellowship talks, and interested readers can view the slides from all of the talks online ( www.atnf.csiro.au/research/conferences/ffsymp2004/ ).
Mike Dopita gave the first talk of the meeting, detailing recent work by his group to understand the ultraviolet-to-radio spectral energy distribution (SED) of starburst galaxies. A principal motivation is to shed light on why various star formation tracers (such as the ultraviolet, far-infrared or radio continuum) tend to correlate with each other, and thus improve on them to better ascertain the star formation history of the universe. Modelling the SED is a difficult business, however, and requires accurate treatment of both the gas and the dust physics, as well as following the evolution of HII regions. An important result of the modelling thus far is a strong dependence of the far-infrared SED on the interstellar pressure, which results from HII regions in high-pressure zones having higher temperatures and smaller radii.
Ron Ekers focused on the mystery posed by the correlation between the radio and far-IR emissions in galaxies, both of which (as mentioned above) are believed to trace the star formation rate. The tightness of the correlation, and the fact that the radio emission is primarily non-thermal in origin, raises the question of what might couple the interstellar magnetic field and cosmic-ray density with the thermal radiation from heated dust. The rather provocative suggestion offered by Ekers was that an increased cosmic-ray flux inhibits low-mass star formation by increasing the ionisation fraction, thereby raising the far-IR luminosity as more mass goes into high-mass stars. In some cases this can lead to a runaway process which would be observed as a starburst.
Dick Manchester rounded off the Federation Fellow talks by describing how the tried and true technique of radio pulsar timing offered new opportunities to explore the frontiers of gravitational wave astronomy. One recent highlight was the discovery with Parkes in 2003 of the first double-pulsar system, known as PSR J0737-3039A/B. Not only does this system offer a fantastic laboratory for seeing relativistic effects in action, but it has also significantly increased the predicted rate of double neutron-star coalescence, an important target for gravity-wave detectors. A far more ambitious application of pulsar timing is to detect the stochastic gravity-wave background by accurately timing a network of the most "regular" pulsars across the sky. Such a program is now underway at Parkes, and has the potential to make the first direct detection of gravity waves.
The symposium ended with a panel discussion, including the three Fellows and moderator Rachel Webster, about the future of Australian astronomy, a timely subject given that the community is preparing its next 10-year plan. Among the themes that were stressed was the importance of student training, especially for developing instrumentation skills and ensuring all students have a basic grasp of research in all areas of astrophysics.
The organisers would like to thank the Stromlo staff for helping to get the Duffield Lecture Theatre ready in time for the meeting (the acoustics are great!), and Sue Little for handling all kinds of last-minute details both before and during the meeting. Support for the symposium came from the three Federation Fellows as well as their host institutions.
Tony Wong
(Tony.Wong@csiro.au)