The First Galaxies Project, led by CI Michele Trenti, is focussed on discovering galaxies during the first billion years after the Big Bang and characterising their properties. These goals are achieved through a combination of observations (primarily in the infrared wavelengths) by some of the most powerful telescopes (space and ground-based) with theoretical and numerical modelling of the expected properties of these galaxies. The brightest candidate first galaxies in the Universe have already been observed by the team with the Hubble Space Telescope, which are being followed up with 3D spectroscopy using the Keck Telescope in Hawaii.

Gravitational Lensing

Searching for such ancient galaxies means looking for sources so distant that their light has travelled for more than 13 billion years before it has reached us.

As the light emitted by distant galaxies passes by massive objects in the universe, the gravitational pull from these objects can distort or bend the light. This is called gravitational lensing. Weak gravitational lensing results in galaxies appearing distorted, stretched or magnified. Although difficult to measure for an individual galaxy, galaxies clustered close together will exhibit similar lensing patterns

The Search for the First Galaxies

To find these exceptionally faint, distant galaxies, our astronomers use the Hubble Space Telescope. They were awarded 500 Orbits in 2017. CI Michele Trenti and his international Brightest of Reionising Galaxies (BoRG) survey team searched for galaxies within the first 700 million years after the Big Bang. The data was acquired over 18 months using a new multi-colour imaging technique. The team has analysed primarily infrared images from Hubble’s Wide Field Camera 3.

Spotting these first galaxies is not always easy, and sometimes relatively nearby objects (only 7-9 billion light years away) masquerade as “imposters” with similar appearance and colour. However, the team’s optimised observational strategy that involves following-up sources to measure their colours more accurately purifies the sample efficiently. In 2018, the team discovered that BoRG 0116+1425 630 galaxy is likely to be an “interloper”, relatively nearby and much younger than previously thought.

The First Galaxies team is also using computational modelling of the first galaxies clustering and also the connection between the dark matter halo assembly and galaxy luminosity function evolution. These simulations will help train neural networks that will be applied to the search catalogue to find better candidate galaxies to observe.

First Galaxies leadership

Michele Trenti
Michele TrentiChief Investigator
Emma Ryan-Weber
Emma Ryan-WeberChief Investigator
Kim-Vy Tran
Kim-Vy TranChief Investigator

Latest IN first galaxies

  • Image titled “James Webb Space Telescope; Deep Field SMACS 0723,” with compass arrows and color key. In the center is a near-infrared image of the galaxy cluster SMACS 0723. At the bottom left are compass arrows indicating the orientation of the image on the sky. The north arrow points in the 11 o’clock direction. The east arrow points toward 8 o’clock. Below the image is a color key showing which NIRCam filters were used to create the image. NIRCam Filters from left to right: F090W is blue; F150W is blue; F200W is green; F277W is green; F356W is orange; and F444W is red. Because this is a deep field image showing objects at many different distances and scales, there is no scale bar.

First Images Released from James Webb Space Telescope

What will Australians see with Webb?Aussie astronomers available for interviews in Melbourne, Sydney, Brisbane, Perth and Canberra.They’re using Webb to look for the first stars, the first galaxies, baby planets, massive black holes.Media contacts: Niall Byrne, niall@scienceinpublic.com.au, [...]

Probing the outskirts of galaxies with quasars

The Monthly Media for May 2022 is from student Jennifer Shi who recently completed a vacation research scholarship at our Swinburne node. Jennifer was measuring key properties associated with known galaxy-quasar pairs, under the [...]