Oskar Klein Centre

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A simulation of a neutron star merging with a black hole. Image credit: Stephan Rosswog (OKC, SU Ast

Hunting for Gravitational Wave Counterparts

Since the groundbreaking first detection of merging neutron stars in gravitational waves and electromagnetic radiation in August 2017, researchers at Stockholm University have continued to search for electromagnetic counterparts – bright transient sources in the sky – in connection with gravitational-wave events.

The simulation of the collapsing core of a star -- two shock waves move out and a core of quarks.

Gravitational waves can show when the core of a dying star breaks down into free quarks

Astronomers have known for a long time that during the death of a massive star gravity causes the core to collapse and then rebound with a bounce into an explosion. Such core-collapse supernovae are some of the most energetic explosions in the Universe. However, we know little about what is happening in the cores of these objects during this process because light cannot escape them.

A plot of the number of events observed vs energy with a red line that shows the expected background

XENON1T sees an excess of electron recoil events

Underneath a mountain in Italy sits 3.2 tonnes of liquid xenon waiting patiently for (among other things) a dark matter candidate particle to recoil off one of the xenon nuclei. And, although this nuclear recoil event has yet to be observed, researchers working on this experiment report that they see more than they expect of something else -- electron recoil events.

An image of Sheng Yang


Interview with Sheng Yang

Sheng is a postdoc in the SU Astronomy Department who is hunting for electromagnetic counterparts to gravitational wave sources. He's ready to start learning to make Swedish food.