Spectral line analysis with the MWA

A series of new spectral line surveys will explore regions of not only our Galaxy but in a selection of other galaxies thought to be distant quasars. These surveys cover a wide range of science goals from understanding diffuse gas within the Galactic Centre through carbon recombination lines, search for HI gas in distance galaxies to understand their formation and evolution over time, search for theorised dark matter particles called axions, and study molecules and recombination lines in star forming regions. The study of spectral lines will also allow us to further our understanding of the noise properties of the Murchison Widefield Array (MWA), use low-frequencies to improve our understanding of chemical enrichment of the low-frequency sky, and assist in understanding the future SKA requirements for the search of biomolecules which is an important goal highlighted in the National Science agenda. Following on from the surveys completed and published during the PhD project of Chenoa Tremblay and with a new set of PhD and summer student projects underway, we will continue to use the pipelines developed on the Pawsey Supercomputer -- Magnus to continue this work

Principal investigator

Chenoa Tremblay chenoa.tremblay@csiro.au
Magnifying glass

Area of science


Systems used

Magnus, Galaxy, Zeus and Topaz

Applications used

Friends of Pawsey
Partner Institution: CSIRO Space & Astronomy | Project Code: pawsey0280

The Challenge

The study of spectral lines at low radio frequencies (<1GHz) has been a discussion across multiple international scientific organisations, but there are only a small number of spectral line surveys below 700 MHz; a significant contribution with published results from this team. The MWA and ASKAP are located in an extreme radio quiet zone, allowing us the ability to continue exploring this frequency range for changes in signal intensity across a narrow frequency band.

It is a major priority by the SKA community and the Australian National government to search for molecular traces of life beyond our solar system. These low frequency molecular line observations compliment this goal by studying the formation mechanisms of sulfur and nitrogen bearing molecules and to look for simple molecular tracers that make up the building blocks of life. In 2021 our focus for molecular line surveys is to explore a significant portion of the frequency band of the MWA with observations of the Galactic Centre in complement with observations from ASKAP. The data processed will be used for multiple comensal studies for molecular lines, carbon recombination lines (atomic), and axion dark matter.

The Solution

Currently, we have ~2000 observations with the MWA covering a selection of possible high -redshifted galaxies, the Galactic Centre across most of the frequency range of the MWA, and new observations with ASKAP. Although most data for ASKAP is processed through the operations team on Galaxy, some post processing and data analysis will utilise this allocation (if awarded) on ASKAP data. Overall, these projects are data intensive and require approximately 1.2 million images of the sky to be made, calibrated, corrected for the ionosphere and made into searchable data cubes. The majority of the data from these projects will be processed by dedicated students in three summer programs with CSIRO and Curtin University and a PhD student at University of Amsterdam. As this type of search at low frequency is still investigating a new area of science, it may require further improvements to the pipeline for the MWA data analysis with the new long-baselines, this proposal represents only a fraction of the 2 million CPU hours estimated to complete this project in 2021 and we would like to maintain the dedicated 100TB disk space on the group file system.

The Outcome

We have processed hundreds of hours of observations which equates to over 10 TB of data final data products between ASKAP and MWA.

List of Publications

Tremblay, C.D., Price, D. and Tingay, S. “A Search for Technosignatures toward the Galactic Centre at 150 MHz” under review, PASA 2021
Tremblay, C.D., Bourke, T., Green, J.A., et al “A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation”, accepted, MNRAS 2021
Tremblay, C.D., Green, J.A., Mader, S.L., Phillips, C.J. and Whiting, M. “First Search for Low-Frequency CH with a Square Kilometre Array Precursor Telescope” 2020, PASA, 37, e055 (Journal Impact factor: 5.067)
Tremblay, C.D., Gray, M.D., Hurley-Walker, N., Green, J.A., Dawson, J., Dickey, J.M., Jones, P.A., Tingay, S.J. and Wong, O.I. “Nitric Oxide and other molecules: Molecular Modelling and Low Frequency Exploration using the Murchison Widefield Array” 2020, ApJ, 905, 65 (Journal Impact factor: 5.745)
Tremblay, C.D., Tingay, S.J. “A SETI Survey of the Vela Region using the Murchison Widefield Array: Orders of Magnitude Expansion in Search Space” 2020, PASA, 37, e035. (Journal Impact factor: 5.067) Altmetric Media Score 1496
Dempsey, J. et al. “GASKAP-HI Pilot Survey Science III: An unbiased view of cold gas in the Small Magellanic Cloud” submitted PASA 2021
Ingallinera, A. et al. “Evolutionary Map of the Universe (EMU): discovering 18-cm OH maser sources in ASKAP continuum images of the SCORPIO field” submitted MNRAS Letters 2021
Velović, V., Filipović M. D., Barnes L., Norris R. P., Tremblay C. D. et al. “AGN jets in the nearby elliptical galaxy NGC 2663” submitted MNRAS 2021
Dickey, J.M. et al “GASKAP Pilot Survey Science II: ASKAP Zoom Observations of Galactic 21-cm Absorption” accepted ApJ 2021
Pingel, N.M. et al “GASKAP-HI Pilot Survey Science I: ASKAP Zoom Observations of HI Emission in the Small MagellanicCloud” accepted PASA 2021
J. Camilo Zapata, A-M Syme, K. N. Rowell et al. “Computational Infrared Spectroscopy of 956 Phosphorus-bearing Molecules” 2021, Front. Astron. Space Sci, doi: 10.3389/fspas.2021.639068 (invited article) (Journal Impact factor: 0.605)