This story is one that literally had me just shaking my head as I read it. According to the press release title: 196 lasers help scientists recreate the conditions inside gigantic galaxy clusters. 

I don’t know exactly how this research got started, but I feel like a couple of researchers were in a café, and one lamented to the other that modeling galaxy clusters in a computer just isn’t accurate enough, and the other was like, “I’ve got some lasers. Let’s just replicate a cluster after lunch tomorrow.”

Again, I don’t know exactly how this research got started, but that’s going to be my headcanon.

Here’s the problem. When we observe clusters of galaxies, we see superheated gas — 10 million Kelvin levels of superheated gas of just protons and electrons that are too hot to form atoms. Exactly how gas this hot comes to exist and stay this hot is something we can’t explain, and uncovering the details of how hot gas, magnetic fields, and time interact hasn’t been an easy process.

So researchers focused 196 lasers at the National Ignition Facility in California on a tiny target and heated that target to white-hot plasma with powerful magnetic fields, and in this short-lived blob, they observed temperature variations that indicate that in this kind of an intense environment, electrons don’t transfer energy the way they normally do. Instead of colliding regularly and radiating heat, these tangled magnetic fields cause electrons to spiral through the fields. This directed motion stops the normal dispersion of energy. In this experiment, they suppressed the conduction of energy by a factor of one hundred!

According to researcher Don Lamb: This is an incredibly exciting result because we’ve been able to show that what astrophysicists have proposed is on the right track”. Colleague Petros Tzeferacis adds, “The simulations were key to untangling the physics at play in the turbulent, magnetized plasma, but the level of thermal transport suppression was beyond what we expected.

And in addition to these needed results, they got to blast a small sample to smithereens with 196 lasers… for science. Who doesn’t love that?

According to a release on this work: More questions remain about the physics of galaxy clusters, however. Though the hot and cold spots are solid evidence for the impact of magnetic fields on the cooling of the hot gas in galaxy clusters, further experiments are needed to understand exactly what is happening. The group is planning its next round of experiments at NIF later this year. 

For now, this work appears in Science Advances and was led by PI Gianluca Gregori.

More Information

University of Chicago press release

University of Oxford press release

“Strong suppression of heat conduction in a laboratory replica of galaxy-cluster turbulent plasmas,” Jena Meinecke et al., 2022 March 9, Science Advances