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A landmark study by researchers at Monash University has produced more evidence that black holes do consistently emit radio waves.
The study, led by associate professor Michael Brown, found that of the 587 nearby galaxies scrutinised, all 40 of the largest examined were found to produce the phenomenon.
The team used data collected from the 36-dish ASKAP telescope in WA that aims to catalogue millions of new galaxies. While black holes have long been known for producing radio waves, the consistency has been questioned, given that new stars in galaxies can also produce them.
The team, therefore, focussed on galaxies with minimal or no star formation – a feat made possible because ASKAP is so sensitive.
“While it’s possible there’s some low-level star formation hidden in these galaxies, black holes seem the most likely cause for what we are seeing,” Professor Brown said.
Undergraduate student Teagan Clarke undertook preliminary work on the investigation despite working under Melbourne’s COVID lockdowns.
“We’ve been able to really dig into this new data to start to uncover the differences in how these galaxies are shining in radio waves,” Clarke said.
“This could tell us about their central black holes and how they power these massive galaxies.”
The final study, titled Radio continuum from the most massive early-type galaxies detected with ASKAP RACS, has been accepted in the publications of the Astronomical Society of Australia.
“Why different galaxies emit far more radio waves than others is a bit of a puzzle,” Associate Professor Brown explained.
“However, we do see that galaxies that are powerful sources of radio waves appear to rotate slower than comparable galaxies that are weak sources of radio waves.
“Getting to the bottom of this is going to be challenging work for myself and my students.”
The ASKAP telescope – or Australian SKA Pathfinder Telescope – opened in Western Australia in 2012 and has been behind multiple breakthroughs.
“ASKAP has 36 dish antennas that work together as one telescope,” explains CSIRO.
“The antennas stand three storeys tall, each with a 12-metre-wide dish, and they are dotted across the outback over an area of about six square kilometres.
“Critical to ASKAP’s unique capability is a novel radio ‘camera’ called a phased array feed receiver, located at the apex of each antenna.
“ASKAP generates data at the rate of 100 trillion bits per second – more data at a faster rate than Australia’s entire internet traffic.
“At the heart of ASKAP is the ‘correlator’, a high-speed digital signal processing system that extracts astronomy signals from this massive amount of data.
“Using the Pawsey Supercomputing Research Centre and custom-written software, we produce science-ready datasets of many terabytes for each observation, served to astronomers through ASKAP’s science archive.”
BY: Adam Thorn
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