Suppressing star formation in quiescent galaxies with supermassive black hole winds

This is the author accepted manuscript. The final version is available from the Nature Publishing Group via https://doi.org/10.1038/nature18006Quiescent galaxies with little or no ongoing star formation dominate the galaxy population above M∗ ∼ 2×10^10 M , where their numbers have increased by a factor of ∼ 25 since z ∼ 2. Once star formation is initially shut down, perhaps during the quasar phase of rapid accretion onto a supermassive black hole, an unknown mechanism must remove or heat subsequently accreted gas from stellar mass loss or mergers that would otherwise cool to form stars. Energy output from a black hole accreting at a low rate has been proposed, but observational evidence for this in the form of expanding hot gas shells is indirect and limited to radio galaxies at the centers of clusters, which are too rare to explain the vast majority of the quiescent population. Here we report bisymmetric emission features co-aligned with strong ionized gas velocity gradients from which we infer the presence of centrally-driven winds in typical quiescent galaxies that host low-luminosity active nuclei. These galaxies are surprisingly common, accounting for as much as 10% of the population at M∗ ∼ 2×10^10 M . In a prototypical example, we calculate that the energy input from the galaxy’s low-level active nucleus is capable of driving the observed wind, which contains sufficient mechanical energy to heat ambient, cooler gas (also detected) and thereby suppress star formation.We are grateful to Yu-Yen Chang for checks on the SED fitting and implied SFR. We thank Stephanie Juneau, Jeffrey Newman, Hai Fu, and Kristina Nyland for discussions and comments. This work was supported by World Premier International Research Center Initiative (WPI Initia- tive), MEXT, Japan, and JSPS KAKENHI Grant Number 15K17603. AW acknowledges support of a Leverhulme Trust Early Career Fellowship. S.P. acknowledges support from the Japan Society for the Promotion of Science (JSPS long-term invitation fellowship). Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS- IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatory of China, New Mexico State University, New York University, Uni- versity of Notre Dame, Observatório Nacional / MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Uni- versidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, Uni- versity of Washington, University of Wisconsin, Vanderbilt University, and Yale University