Untangling how violent cosmic flows heat the universe
The universe is full of powerful streams of matter launched by violent events such as exploding stars, black hole jets, and stellar winds. When these flows slam into surrounding space at enormous speeds, they generate shock waves that light up the cosmos and shape how galaxies evolve.
Yet for decades, scientists have struggled with a deceptively simple question: how is the energy of these extreme flows converted into heat when particles almost never collide?
In a new study published in The Astrophysical Journal Letters, researchers used large-scale, three-dimensional simulations to peer inside these collisionless plasmas and track how energy is redistributed between particles. Their results reveal that most of the heating occurs later than previously assumed, driven by the twisting and kinking of filament-like electric currents. These structures act like tiny cosmic dynamos, amplifying magnetic fields and transferring energy to particles in a fundamentally three-dimensional process.
Crucially, the study shows that electrons — the particles responsible for much of the radiation astronomers observe — receive only a small fraction of the available energy, while heavier ions carry most of the heat. For realistic plasmas like those found in supernova remnants, electrons end up with only a few percent of the original energy of the flow.
This finding helps resolve long-standing puzzles in astronomical observations, where electron temperatures appeared surprisingly low compared to theoretical expectations.
By uncovering the hidden mechanisms that govern energy flow in violent cosmic plasmas, this research brings scientists closer to a unified picture of how the universe’s most energetic events heat and transform their surroundings. It also arrives at a timely moment, as new laboratory plasma experiments and high-resolution simulations are beginning to probe these extreme conditions directly.
To know more:
Alexis Marret and Frederico Fiuza, Energy partition in collisionless counterstreaming plasma.
The Astrophysical Journal (2026), DOI: 10.3847/2041-8213/ae3060
Photo source and credits: NASA/HST
