From University of Melbourne (AU): “New theory on the origin of Dark Matter”


From University of Melbourne (AU)

16 Oct 2020
Lito Vilisoni Wilson
+61 466 867 909

While portions of the work were completed by hand, made possible by a series of simplifying approximations, the results for the study were validated by sophisticated computational calculations. Credit: Michael Baker.

A recent study from the University of Melbourne proposes a new theory for the origin of dark matter, helping experimentalists in Australia and abroad in the search for the mysterious new matter.

The work has been published in Physical Review Letters and describes how expanding bubbles in the early universe may be the key to understanding dark matter.

“Our proposed mechanism suggests that the dark matter abundance may have been determined in a cosmological phase transition,” said Dr Michael Baker, a Postdoctoral Research Fellow at the University of Melbourne and one of the authors.

“These phase transitions are expected to have taken place in the early universe and can be similar to bubbles of gas forming in boiling water. We show that it is natural to expect dark matter particles to find it very difficult enter these bubbles, which gives a new explanation for the amount of dark matter observed in the universe.”

Although many experiments have searched for particle dark matter, none have yet been successful. Most experiments have searched primarily for Weakly Interacting Massive Particles, which has been the favoured dark matter candidate for decades. However, these experiments have not yet seen anything, which really motivates theorists to think outside the box.

Yale Haloscope Sensitive To Axion CDM -HAYSTAC Experiment a microwave cavity search for cold dark matter (CDM)

PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN

LUX dark matter experiment Photomultiplier tubes, which collect light, were installed in this frame for the experiment.

LBNL LZ Dark Matter project at SURF, Lead, SD, USA.

Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment.

“We know dark matter is out there, but we don’t know much else,” said Dr Baker. “If it’s a new particle then there’s a good chance that we could actually detect it in a laboratory. We could then pin down its properties, like its mass and interactions, and learn something new and deep about the universe.”

The research, which was done in collaboration with Assistant Professor Andrew Long from Rice University, Texas, and Professor Joachim Kopp from CERN (CH) and the University of Mainz (DE), points the way for new experimental strategies for searching for dark matter.

“One exciting aspect about the idea is that it works for dark matter particles that are much heavier than most other candidates, such as the famous `Weakly Interacting Massive Particles’, on which most experimental searches in the past were focused,” said Professor Kopp. “Our work, therefore, motivates the extension of dark matter searches towards heavier masses.”

The findings could be especially important for the future of experimental dark matter searches in Australia.

The Stawell Underground Physics Laboratory, which is currently under construction in regional Victoria, one kilometre beneath the ground in a disused gold mine, will be the first underground particle physics laboratory in the Southern Hemisphere, and will house several dark matter search experiments in the years to come.

New theoretical proposals will help drive design experiments that can test the widest range of dark matter candidates, giving scientists the best chance of uncovering the mystery of dark matter.

See the full article here .

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The University of Melbourne (AU) (informally Melbourne University) is an Australian public research university located in Melbourne, Victoria. Founded in 1853, it is Australia’s second oldest university and the oldest in Victoria. Times Higher Education ranks Melbourne as 33rd in the world, while the Academic Ranking of World Universities places Melbourne 44th in the world (both first in Australia).

Melbourne’s main campus is located in Parkville, an inner suburb north of the Melbourne central business district, with several other campuses located across Victoria. Melbourne is a sandstone university and a member of the Group of Eight, Universitas 21 and the Association of Pacific Rim Universities. Since 1872 various residential colleges have become affiliated with the university. There are 12 colleges located on the main campus and in nearby suburbs offering academic, sporting and cultural programs alongside accommodation for Melbourne students and faculty.

Melbourne comprises 11 separate academic units and is associated with numerous institutes and research centres, including the Walter and Eliza Hall Institute of Medical Research, Florey Institute of Neuroscience and Mental Health, the Melbourne Institute of Applied Economic and Social Research and the Grattan Institute. Amongst Melbourne’s 15 graduate schools the Melbourne Business School, the Melbourne Law School and the Melbourne Medical School are particularly well regarded.

Four Australian prime ministers and five governors-general have graduated from Melbourne. Nine Nobel laureates have been students or faculty, the most of any Australian university.