In his award-winning PhD thesis, entitled “Solving the Cooling Flow Problem through Mechanical AGN Feedback”, Massimo Gaspari studied the intimate relationship between cooling and black hole heating in the cosmic evolution of baryons.

In previous classic theories, radiative cooling of plasma would lead to the cooling catastrophe, a massive inflow of condensing and star-forming gas that would manifest itself in the core of galaxies, groups, and clusters. Using 3D hydrodynamic simulations, executed on large supercomputers, Gaspari showed that mechanical, bipolar outflows, which are driven by the central active galactic nucleus (AGN), can dramatically quench the cooling rates for several billion years. At the same time this process preserves the cool-core structure of the system.

Furthermore, the mechanical AGN feedback can reproduce key features such as X-ray cavities, weak shocks, metals uplift, and turbulence. The latter is an essential ingredient to drive nonlinear thermal instabilities, which cause the condensation of extended cold gas clouds. These are a residual of the quenched cooling flow and can later provide fuel for the supermassive black hole at the centre.

Thus, cold accretion triggers feedback, reloading the self-regulated loop in a never-ending “dance” between heating and cooling. In his thesis, Gaspari tested several models, dissecting the essential characteristics for a realistic AGN feedback, while paying particular attention to consistency with observations.

For this analysis, Gaspari will receive the Gratton award in its 11th edition - the most prestigious Italian prize given to young astronomers. The award honours the memory of the Italian astronomer Prof. Livio Gratton, who studied quasars and cosmology at the Milan observatory and the National Observatory of Cordoba. It is supported by the Eta Carinae and Tuscolana Associations, the Gratton family, the Frascati district, and the National Institute for Astrophysics (INAF). Every two years, an international committee selects a researcher from an Italian University who has made an innovative and significant contribution to Astronomy and Astrophysics with his/her PhD thesis. In addition to the certificate, the awardee receives a monetary sum of €7,500. The official award ceremony will take place in Frascati (Rome) on 12 October 2013.

In 2012, Massimo Gaspari joined the Max Planck Institute for Astrophysics as a postdoctoral researcher in the High Energy Astrophysics group, working mainly with E. Churazov and R. Sunyaev.