Workshop HomeAccommodationProgrammeRegistrationTravelContacts

Science with SKAMP Workshop

Widefield Spectroscopy of the Southern Radio Sky

ABSTRACTS

Professor Jeremy Darling

Talk: HI 21 cm Absorption Line Searches and Science with SKAMP

Neutral hydrogen 21 cm absorption line studies bloomed in the late 1970s and, coupled with optical spectroscopy, provided new insights into gas evolution and metal enrichment spanning much of the history of the universe. We now live in a much "richer" RFI environment, and despite large gains in sensitivity, bandwidth, computing, and electronics, most spectral line searches are frustrated by anthropogenic signals. I will highlight the scientific benefits and challenges of HI 21 cm absorption line studies, including new pointed and "blind" detection strategies. I will discuss recent new 21 cm detections and explore how the various detection strategies may be applied to surveys with SKAMP.

Dr Steve Curran

Talk: The best candidates for redshifted atomic and molecular absorption

With the next generation of radio interferometers/SKA pathfinders, we expect to uncover a large number of HI, as well as the very rare OH, absorption systems at high redshift. These can be used to address many important issues such as measuring baryonic content of the Universe, probing large-scale structure and galaxy evolution, as well as obtaining independent measurements of various combinations of fundamental constants at large look-back times. Here we summarise our recent results regarding just where we expect the HI and OH absorption systems to be found:

1. HI in absorbers intervening distant quasars - how from the geometry of a flat expanding Universe we expect a large detection rate at z < 1.

2. HI absorption associated with the host galaxy/quasar - we show that the optical selection of these objects, particularly at high redshift, greatly reduces the 21-cm detection rate. Blind surveys are therefore expected to improve significantly on current detection rates.

3. OH absorption - how through colour selection we expect to significantly increase the number of redshifted OH absorbers above the paltry five currently known. Again, the pursuit of the dimmest objects, through blind surveys, being the best strategies.

Professor Geoff Bower

Talk:Wide Field Transient Surveys

The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, recent discoveries from limited surveys and serendipitous discoveries indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenonmena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The current generation of new centimeter-wave radio telescopes such as the ATA, SKAMP, and ASKAP will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the SKA. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars. While proving the variable sky, these surveys will also provide unprecedented information on the static radio sky. I will present results from three ATA surveys: the Fly's Eye survey, the ATA Twenty CM Survey (ATATS), and the Pi GHz Survey (PiGSS).

Dr Tara Murphy

Talk: Transient and Variable Science with SKAMP SKA Pathfinders will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. Their wide-field survey capabilities will enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, intra-day variables, radio supernovae and orphan afterglows of gamma ray bursts. In addition they will allow us to probe unexplored regions of phase space where new classes of transient sources may be detected.

I will review the transient and variable science projects being planned on two SKA Pathfinders: The Murchison Widefield Array (MWA), The Australian SKA Prototype (ASKAP). I will also discuss our plans for transient and variable science with SKAMP.

Keith Bannister

Talk: A 12-Year, Southern Sky Survey for Radio Variability and Transients using MOST

The Molonglo Observatory Synthesis Telescope (MOST) has been imaging the southern skies at 843 MHz since 1996. Data were taken as part of major surveys (MGPS-1, SUMSS, MGPS-2), as part of monitoring campaigns, and towards specific targets of interest. The resulting sets of images now cover some parts of the sky multiple times, and with a range of candences.

This data-set provides an unprecedented opportunity to characterise the variable sky at 843 MHz on time scales ranging from one day to many years.

I will present an overview of the MOST archive and our identification algorithms along with the resulting discovery of more than 40 slowly varying radio sources in the southern sky. I will conclude by discussing some of the techniques and pitfalls of variable and transient detection, as will need to be addressed for SKAMP, ASKAP and other future radio surveys.

Dr David Jauncey

Talk: Forty years of VLBI in the Land of Oz; some lessons learned and a suggestion

VLBI in Australia has developed steadily and successfully over the last 40+ years, and has involved many people and many institutes. I shall briefly review this development, from an historical perspective, point out some of the critical developments, and suggest some possibilities for the near-term future.

Professor Jeremy Darling

Talk:Redshifted OH Lines with SKAMP: Detection and Science

The detection of OH lines at redshifts z > 0.25 has been a serious challenge with current telescope facilities due to the combination of weak lines and severe radio frequency interference in the sub-GHz bands. With SKAMP in mind, I will discuss the scientific merits of redshifted OH line detection and studies, including OH megamasers (OHMs), OH absorption, and OH conjugate lines. For OHMs in particular, we can now interpret the physical meaning of detected lines in terms of major mergers, star formation, and the magnetic field environment. I will outline detection approaches, pointed and "blind," for potential SKAMP surveys and highlight lessons learned from recent detections of OHM interlopers in the ALFALFA HI 21 cm survey, from a pointed Green Bank survey for OHMs, and from numerous searches for molecular absorption systems.

Dr D.J. Saikia

Talk: Diffuse, non-thermal emission in radio sources

Diffuse, non-thermal emission in radio sources is usually due to old electrons and can be seen as halos and relics in clusters of galaxies, halos associated with nearby spiral galaxies, relic lobes of double-lobed radio sources and radio emission due to an ealier cycle of activity in an AGN. This talk will give a brief overview, and then focus on relic lobes and diffuse emission from earlier cycles of activity in radio galaxies and quasars. A very striking example of such episodic jet activity is when a new pair of radio lobes is seen closer to the nucleus before the `old' and more distant radio lobes have faded.

Such sources have been christened as double-double radio galaxies. We summarise the results of our search for such objects and multi-frequency studies of a few of these.

Dr Tom Landecker

Talk: Polarimetry of the Galactic Plane with Arcminute Angular Resolution'''

A survey of Galactic polarized emission covering 1200 square degrees has been completed as part of the Canadian Galactic Plane Survey (CGPS). This survey incorporates aperture-synthesis data with single-antenna data to achieve both high angular resolution and complete coverage of structure down to the largest scales. The high-resolution elements come from the DRAO Synthesis Telescope and the single-antenna data come from the DRAO 26-m Telescope and the Effelsberg 100-m Telescope. Angular resolution is 1 arcminute at 1420 MHz.

I will present some of the highlights of the CGPS survey and will use them to illustrate the potential of SKAMP to extend our knowledge of the detailed structure of the Galactic magnetic field and of the role of magnetic fields in interstellar processes.