Much like other cosmic beasts, black holes grow by accreting mass from a surrounding disk. And they are messy eaters. To conserve the disk's angular momentum and prolong the feast, they eject ionized gas in a wide fan outside the accretion disk plane. These plasma outflows, or black hole winds, leave a mark in the absorption lines of the X-ray spectra, but the exact mechanism responsible for launching the winds is not clear. Using magnetohydrodynamics simulations, Keigo Fukumura and colleagues have now found compelling reasons to point the finger at a likely culprit: the magnetic field.
Black hole winds of magnetic origin are expected to be very fast (up to 0.2c). Fukumura and co-workers previously used magnetohydrodynamic wind models to explain the properties of such ultrafast outflows in the X-ray spectra of supermassive black holes, giving weight to the magnetic origin scenario. Now Fukumura et al. have extended their approach and found that it works equally well for a stellar-mass black hole. This suggests that the magnetic origin of black hole winds is a universal feature across the mass spectrum. IG
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Georgescu, I. Gone with the wind. Nature Phys 13, 321 (2017). https://doi.org/10.1038/nphys4100