Galaxy and stars

Gravitational wave detector may shed light on dark matter

Image credit: Pixabay

Scientists from the University of Zurich (UZH) believe an orbiting laboratory called the Laser Interferometer Space Antenna (LISA) will allow astrophysicists to observe gravitational waves emitted by black holes as they collide with other black holes.

Planned for launch in 2034, LISA is a collaborative project between the European Space Agency and Nasa, with aims to become the first dedicated space-based gravitational wave detector.

It will consist of three spacecraft separated by 2.5 million kilometres in a triangular formation, following the Earth in its orbit around the Sun. Laser beams will be relayed back and forth between the spacecraft and the signals combined to search for gravitational wave signatures that come from distortions of space-time.

These minimal distortions could potentially add a new sense to scientists’ perception of the universe and enable them to study phenomena invisible in different light spectra, according to the researchers.

Scientists from the Centre for Theoretical Astrophysics and Cosmology at UZH, with colleagues from Greece and Canada, have found that LISA will not only be able to measure previously unstudied waves, but could also help to unveil secrets surrounding dark matter.

Dark matter particles are thought to account for approximately 85 per cent of the matter in the universe. Although they are still hypothetical, with the name referring to their ‘hiding’ from all previous attempts to see and study them, calculations suggest that many galaxies would be torn apart instead of rotating if they weren’t held together by a large amount of dark matter.

This hypothesis applies to dwarf galaxies, as while such galaxies are small and faint, they are the most abundant in the universe. They are of particular interest to astrophysicists because their structures are dominated by dark matter, making them ‘natural laboratories’ for studying this elusive form of matter.

As part of the study, PhD student Tomas Ramfal designed and carried out high-resolution computer simulations of the birth of dwarf galaxies, calculating the interplay of dark matter, stars and the central black holes of these galaxies.

Snapshots of the 120 million particle simulation of two merging dwarf galaxies, which each contain a blackhole, between 6 and 7.5 billion years

Snapshots of the 120 million particle simulation of two merging dwarf galaxies, which each contain a blackhole, between 6 and 7.5 billion years

Image credit: University of Zurich

The team of scientists from Zurich discovered a strong link between the merger rates of these black holes and the amount of dark matter at the centre of dwarf galaxies, as shown in the photo above. Measuring gravitational waves emitted by merging black holes can provide hints about the properties of the hypothetical dark matter particle.

For the first time, the newly found connection between black holes and dark matter can now be described in a mathematical and exact way, according to group leader Lucio Mayer.

However, it is far from being a chance finding, stresses Mayer, who said: “Dark matter is the distinguishing quality of dwarf galaxies. We had therefore long suspected that this should also have a clear effect on cosmological properties.”

Preliminary results of the researchers’ simulations are said to have been met with excitement at meetings of the LISA consortium, with the connection coming at an opportune moment, just as preparations for the final design of LISA are under way.

The study was reported in the journal Astrophysical Journal Letter.

In June, the daughter of the late Stephen Hawking revealed at his memorial service the physicist's voice will be beamed into space and towards the nearest black hole, carrying a message of peace and hope.

Also, earlier this January, scientists gathered data on a series of mysterious, intermittent radio waves emanating from a distant object in space but were only able to theorise about what causes them.

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