ACAMAR Themed Workshop on VLBI: Towards a Sino-Australia high-sensitivity VLBI arrray

China and Australia are located in similar time zones, and an equatorial region of the sky can be simultaneously observed by telescopes in both countries. In addition, the combined array including the Chinese VLBI Network, the southern hemisphere Long Baseline Array (LBA), the Indian GMRT and the South African SKA can offer excellent uv-coverage for […]

ESO's Very Large Telescope (VLT), which houses the Multi Unit Spectroscopic Explorer (MUSE). Two teams of Australian-based astronomers have recently each been awarded substantial amounts of observing time on this in-demand instrument. Credit: John Colosimo (colosimophotography.com)/ESO.

Two teams of astronomers led by The University of Sydney and by The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR/UWA) have recently each been awarded substantial amounts of observing time on one of the most in-demand instruments at the European Southern Observatory (ESO) – the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) – as part of ESO’s Large Program process.

Astronomers Jesse van de Sande (University of Sydney), Barbara Catinella and Luca Cortese (both from ICRAR/UWA) were awarded 317 hours and 173 hours respectively over the next two years, allowing them to lead international teams of astronomers to perform deep observations of the Milky Way’s galactic cousins and reveal the physics of star formation and galaxy evolution in some of the most massive structures in the Universe. 

The instrument in question, VLT/MUSE, is an integral field spectrograph yielding 3D views of galaxies, and observing time is highly sought-after by astronomers located in ESO member states and those located in Australia, ESO’s strategic partner. Less than one in five requests submitted are approved every year. With such a competitive application process to navigate, the hundreds of hours awarded to the following projects goes to show how Australian-based astronomers are proving themselves on the world’s stage, continuing to compete and collaborate with the best in their respective fields.

The winning projects
GECKOS – led by Dr Jesse van de Sande, University of Sydney

The GECKOS project aims to better understand our own Milky Way Galaxy’s unique evolutionary history by comparing it to its extragalactic cousins. A survey conducted by Jesse and his team will provide a detailed cross-section of 35 galaxies with similar properties to our own Galaxy, taking the unique approach of only observing galaxies that appear in a side-on orientation from our perspective here on Earth. Using MUSE, the team will be able to split the light they see coming from each galaxy into many different colours – a process known as spectroscopy. MUSE is able to make 90,000 of these detections during a single observation run, building a three-dimensional map of the individual colours present in the captured light from the target galaxy. This will allow the GECKOS team to determine the chemical composition of its stars and gas, with the side-on viewpoint also giving them a chance to study vertical outflows of gas and detect faint signatures that were left behind by small galaxy mergers a long time ago.

The disk galaxies targeted by GECKOS were selected to have a wide range of internal structures and star-formation rates, allowing the team to probe a variety of different evolutionary histories. GECKOS will be transformative by moving away from single observations of edge-on galaxies to a larger sample that reflects all types of disk galaxies we see in the nearby Universe. With these detailed measurements, the GECKOS team hopes to answer the one crucial question about galaxy evolution that cannot be solved by looking at our Milky Way alone – how important are external events, like mergers with satellite galaxies, compared with the internal processes that already happen inside the galaxy?

GECKOS will give us an exquisite view of how galaxies like our own Milky Way may have evolved over time, which is only possible by having access to MUSE – the world’s best panoramic integral-field spectrograph on the Very Large Telescope, through Australia’s strategic partnership with ESO.

Dr Jesse van de SandeUniversity of Sydney
Some of the target galaxies for the GECKOS team. From left: NGC 5010, NGC 5775, and NGC 1032. Credit for each image: ESA/Hubble & NASA.
MAUVE – led by A/Prof Barbara Catinella and A/Prof Luca Cortese, ICRAR/UWA

The MAUVE program is designed to reveal the physics of star formation and galaxy evolution in the most massive structures in the Universe – galaxy clusters. The study led by Barbara and Luca will investigate what happens within the disks of 40 individual galaxies that move through the dense environments of massive galaxy clusters. It is understood that galaxies plunging into clusters come into contact with the hot plasma spread throughout the cluster, known as the intergalactic medium. The interaction with this plasma strips away the cold gas on the outer regions of galaxies, thus reducing the total amount of fuel available for making new stars. Even in the densest parts of the cluster, however, there is still evidence for significant star formation ­– a mystery that the team led by Barbara and Luca is looking to solve with access to VLT/MUSE.

The team will also seek to reconstruct the history of star formation in cluster galaxies for the first time, assess how gas outflows affect the clusters overall, and deliver rich data sets using MUSE that will help the next generation of astronomers studying these environments. Building on an existing study using the Atacama Large Millimeter/submillimeter Array (ALMA) – operating at the highest radio frequencies – MAUVE aims to showcase Australia’s growing expertise in galaxy evolution studies, and how the combined power of optical spectroscopy and radio observation is fast making our astronomers world leaders in this field.

We are extremely excited about this project and the unexpected discoveries to come ­– only possible thanks to the Strategic Partnership Agreement between ESO and the Australian Government.

A/Prof Barbara CatinellaICRAR/UWA

This showcases the type of opportunities that a full Australian membership of ESO could provide to Australian researchers, not only in terms of scientific discoveries but also in the development of new techniques of analysis and training future generations of scientists.

A/Prof Luca CorteseICRAR/UWA
Five galaxies from the MAUVE sample. From left: NGC 4522 (NASA & ESA), NGC 4302 / NGC 4298 (NASA, ESA, and M. Mutchler (STScI)), and NGC 4568 / NGC 4567 (International Gemini Observatory/NOIRLab/NSF/AURA).

Australian-based astronomers are eligible to apply for time on the VLT and other ESO instruments thanks to the ten-year Strategic Partnership between Australia and ESO. The Strategic Partnership is enabled by the Australian Government Department of Industry, Science and Resources (DISR). Astronomy Australia Limited (AAL) supports DISR by overseeing activities and stakeholder communications to ensure Australian astronomers get the best information and access to ESO – see AAL’s ESO webpage for more.

GECKOS (Generalising Edge-on galaxies and their Chemical bimodalities, Kinematics, and Outflows out to Solar environments) is led by Jesse van de Sande (PI; SIfA, University of Sydney), Amelia Fraser-McKelvie (ICRAR/UWA), Deanne Fisher (CAS, Swinburne University of Technology), Marie Martig (ARI, Liverpool John Moores University), and Michael Hayden (SIfA, University of Sydney). The full team includes researchers from international universities as well as several Australian institutions, such as ICRAR/UWA, Macquarie University, The University of New South Wales, and the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).

The MAUVE (MUSE and ALMA Unveiling the Virgo Environment) program is led by Barbara Catinella and Luca Cortese from ICRAR/UWA, and includes researchers from Europe, North and South American countries as well as researchers from various Australian institutions (University of Sydney, Curtin University, Swinburne University of Technology, Macquarie University and ASTRO 3D).

GECKOS and MAUVE are open collaborations, with interested members of the Australian community welcome to get in touch with the PIs Jesse van de Sande (GECKOS) and Barbara Catinella and Luca Cortese (MAUVE) if they wish to contribute.

For more information, please contact the following representatives from the relevant institutions:

The University of Sydney: Jesse van de Sande (GECKOS PI): [email protected] or Wilson da Silva, Media Adviser (Science): [email protected]  

ICRAR/UWA: Barbara Catinella (MAUVE PI): [email protected],
Luca Cortese (MAUVE PI): [email protected] or
Cass Rowles, Cosmic Communicator/Digital Content Coordinator: [email protected]

ASTRO 3D: Ingrid McCarthy, Chief Operating Officer: [email protected]

AAL: Romy Pearse, Communications Manager: [email protected]​astronomyaustralia.org.au