title: GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.
abstract: Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow.
authors.affiliation: Department of Physics, Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, Zurich 8093, Switzerland. benny.trakhtenbrot@phys.ethz.ch.
authors.forename: Benny
authors.initials: B
authors.lastname: Trakhtenbrot
authors.affiliation: Department of Physics, Yale University, Post Office Box 208120, New Haven, CT 06520-8120, USA. Yale Center for Astronomy and Astrophysics, 260 Whitney Avenue, New Haven, CT 06520-8121, USA. Department of Astronomy, Yale University, Post Office Box 208101, New Haven, CT 06520-8101, USA.
authors.forename: C Megan
authors.initials: CM
authors.lastname: Urry
authors.affiliation: Yale Center for Astronomy and Astrophysics, 260 Whitney Avenue, New Haven, CT 06520-8121, USA. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Civano
authors.affiliation: Max-Planck-Institut für Extraterrestrische Physik (MPE), Postfach 1312, 85741 Garching, Germany.
authors.forename: David J
authors.initials: DJ
authors.lastname: Rosario
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Elvis
authors.affiliation: Department of Physics, Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, Zurich 8093, Switzerland.
authors.forename: Kevin
authors.initials: K
authors.lastname: Schawinski
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA.
authors.forename: Hyewon
authors.initials: H
authors.lastname: Suh
authors.affiliation: INAF-Osservatorio Astronomico di Roma, Via di Frascati 33, I-00040 Monteporzio Catone, Rome, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Bongiorno
authors.affiliation: Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK.
authors.forename: Brooke D
authors.initials: BD
authors.lastname: Simmons