Gonville & Caius College postgraduate student Frank Qu (Cosmology 2018) collaborated on a study to map dark matter in the universe and further support Einstein’s theory of general relativity.

Frank, a PhD student at the University of Cambridge’s Department of Applied Mathematics and Theoretical Physics, presented the findings at the CMB x LSS conference at the Yukawa Institute for Theoretical Physics in Kyoto University, Japan earlier this month.

In a set of papers submitted to The Astrophysical Journal, Frank and his colleagues used data from the Atacama Cosmology Telescope in Chile to produce the most detailed map of dark matter (the unseen mass thought to account for 85% of the matter in the universe) to date and used it to test the Standard Cosmology model that uses Einstein’s theory of General relativity as backbone.

Dark matter could be plotted on a map hundreds of millions of light years across, using data collected by the telescope, as Frank explains.

“We have already learned a lot of information about the origin and the composition of the universe by just looking at light emitted since the Big Bang, the cosmic microwave background,” says Frank, who completed a Part III Masters course in Maths at Caius before starting his PhD in 2019.

“But it turns out that it contains much more information that we can extract, because as it travels from the beginning towards us it gets distorted and wrapped by the gravitational pull of the intervening dark matter.

“All the matter, most of which we can’t see and we don’t understand, acts as a magnifying glass, bending or lensing the background light. By measuring these subtle distortions we can use these to reveal information about the properties and distribution of dark matter.

“We’re looking at how this light is distorted and working backwards to build a map of the dark matter distribution.”

Frank, pictured, who was inspired to choose Caius by the College’s long association with Professor Stephen Hawking, a Fellow for 52 years, says his work supports long-standing theory.

Frank adds: “The current cosmology model has at its backbone the theory of general relativity developed by Einstein. This theory was also an important tool used by Stephen Hawking in his research.

“While earlier studies using mainly galaxies as a backlight pointed to cracks in the standard cosmological model, our findings provide new reassurance that our fundamental theory of the universe holds true.

“By comparing observations of the dark matter distribution in the universe today to predictions made soon after the Big Bang, we have found remarkable agreement in a powerful test of structure growth spanning billions of years.”

Frank is scheduled to take up a KIPAC Fellowship at SLAC National Accelerator Laboratory in Stanford in the autumn.

For further information, read the University of Cambridge news article: New findings that map the universe’s cosmic growth support Einstein’s theory of gravity | University of Cambridge