(This is a guest post by Edmond Cheung at the Kavli IPMU)
While there have been many recent studies addressing how galaxies shut off, or quench, their star formation, an equally interesting yet relatively unstudied question is how these quenched galaxies remain quenched. This is interesting because these quiescent galaxies often contain gas (from stellar mass loss or mergers) that—if left unimpeded—should cool and form stars. But since we know that quiescent galaxies have not formed a significant amount of stars since they’ve been quenched, there must be something that prevents this gas from cooling.
In the new study by Cheung et al. 2016, Nature, 533, 504, this ‘something’ has been found. Using the ongoing SDSS IV MaNGA survey, which takes resolved spectroscopy for 10,000 nearby galaxies, Cheung et al. discovered a new class of quiescent galaxies—dubbed “red geysers”—that hosts outflowing winds powerful enough to heat ambient gas and suppress future star formation. These winds are manifested in bisymmetric emission features (in H-alpha, [OII], and other strong lines) and are likely powered by their weakly-accreting supermassive black holes.
To highlight the key characteristics of this class, Cheung et al. focus on a prototypical red geyser, which they nicknamed “Akira”—a reference ...