SUBWAYS Project
[A full description of the project, available data, results, people involved, and publications, can be found on the project website]
Artistic view of multiphase AGN-driven winds highlighting the different phases and scales that are involved in the outflow. The wind propagates from the central engine (< 1 pc; a), through the surrounding ISM (1 pc–1 kpc; b), out to the boundaries of the host galaxy (> 10 kpc; c). SUBWAYS investigates the outflow in its launching phase, when the gas is highly ionized, and the presence of fast-moving material can be revealed in X-rays. (figure adapted from Cicone et al. 2018, Nat. As. 2, 176).
The SUBWAYS project (an acronym for “Supermassive Black Holes Winds in the X-rays”) collected XMM-Newton observations during AO18 for more than 400 hours (1.46 Ms, PI prof. Marcella Brusa, DIFA-UniBo) to observe a sample of 17 quasars at redshift z~0.1-0.4, i.e. in a cosmic epoch (the past 1-4 Gyr) where the presence and properties of AGN-driven winds has not yet been explored in the X-rays with the needed accuracy. Archival XMM-Newton observations of another five QSOs were used to expand the sample to 22 targets in total.
The aim of SUBWAYS is to provide direct support on QSO feedback models by deriving meaningful constraints on the frequency and properties of the winds propagating at sub-relativistic velocity (dubbed “Ultra Fast Outflows”, UFO) on the scales closest to the central Super-Massive Black Hole (SMBH).
So far, the characterization of UFOs has been limited – with few exceptions – to samples of low-power AGN in the local Universe. SUBWAYS guarantees the needed step forward, observing for the first time and for an adequate time the best possible candidates among the sources at the highest luminosity, to investigate the outflow phenomenon for the first time with a statistical approach and to study the relation of UFOs with the winds observed at larger scales and in different gas components.
The project is the third largest ever approved in a single XMM-Newton cycle during its 20-year activity (see here). It is also the first project of such size to be awarded to an Italian woman. The SUBWAYS team includes 47 scientists from 10 countries (Italy, The Netherlands, USA, Mexico, UK, Spain, Poland, Germany, France, and Israel), among the major experts worldwide in the fields of UFOs and galactic winds and in general AGN and Quasar’s physics and evolution, both from the observational and theoretical point of view.
Involved OAS Staff: Giorgio Lanzuisi, Andrea Comastri, Massimo Cappi, Mauro Dadina, Paola Grandi, Eleonora Torresi, Roberto Gilli, Marco Mignoli.