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At Phys.org: Astronomers find cosmic rays driving galaxy’s winds


Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered an important new clue about how galaxies put the brakes on vigorous episodes of star formation. Their new study of the neighboring galaxy M33 indicates that fast-moving cosmic ray electrons can drive winds that blow away the gas needed to form new stars.

VLA finds cosmic rays driving galaxy's winds
Artist’s illustration of cosmic ray driven winds (blue and green) superimposed on a visible-light image of the Triangulum galaxy M33 (red and white) observed with VLT Survey Telescope at ESO’s Paranal Observatory in Chile. Credit: Institute for Research in Fundamental Sciences- IPM & European Southern Observatory (ESO).

Such winds are responsible for slowing the rate of star formation as galaxies evolve over time. However, shock waves from supernova explosions and energetic, black hole-powered jets of material coming from galactic cores have been considered the primary drivers of those winds. Cosmic rays were thought to be minor contributors, particularly in galaxies like M33 that have regions of prolific star formation.

Stars much more massive than our sun speed through their life cycles, ultimately exploding as supernovae. The explosive shock waves can accelerate particles to nearly the speed of light, creating cosmic rays. Enough of these cosmic rays can build pressure that drives winds carrying away the gas needed to continue forming stars.

Complete article at Phys.org.

A galaxy’s ability to continue the process of star formation throughout its history is an important factor contributing to its potential habitability. [Reasons.org]


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