Contact: asheinis at aao dot gov dot au
(+61) 2 9372 4821
I am the Head of Instrumentation at the AAO. In addition I am an Adjunct Associate Professor of Astronomy at the Sydney Institute for Astronomy (SIfA). My interests are in Astronomical Instrumentation (spectrographs, imagers in the visible and NIR as well as AO and novel observational and instrumentation tools). On the science end of things I am interested in the AGN/Host Galaxy interaction, feedback and the influence of bona fide QSO's on their hosts.
Before coming to sunny Sydney Australia I was an assistant Professor at the University of Wisconsin in Madison. Prior to that I was an NSF Postdoctoral fellow at the CFAO in Santa Cruz. I did my Ph.D. in Santa Cruz as well working for Joe Miller on AGN Hosts and Jerry Nelson on Instrumentation.
When I am not building instruments I work on AGN/Galaxy interaction. Like every instrumentalist, who is actually paying attention, I am motivated by deep and far-reaching problems in astrophysics. The problem I am studying builds on the connection between galaxies and their central black holes that has emerged over the last decade. Every galaxy with a bulge contains a nuclear supermassive black hole (SMBH) and that black hole mass is correlated with galaxy stellar velocity dispersion (the MBH-σ relation), suggesting that the growth mechanisms of the black hole and galaxy must be connected. This is surprising as the SMBH gravitational volume of influence is 14 orders of magnitude smaller than the typical large galaxy in which it resides! This situation prompted many studies of Active Galactic Nuclei (AGN) host galaxies in which the galaxy actively feeds gas and dust to its SMBH. These studies have found evidence that in fact the active phase occurs in most or all galaxies. My work focuses on the detailed study of this phase in order to gain insight into the relationship between the SMBH and its host galaxy. Direct measurement of the properties of the host galaxies of the brightest AGN is extremely difficult as often the AGN outshines the rest of its host by more than an order of magnitude.
In order to understand the nature of the stars and gas in the host galaxy, detailed spectroscopic measurements are required, which allow one to fit the age, composition, and velocities of the underlying stars and gas to theoretical models. We have made the first direct velocity dispersion measurements of the host galaxies of bonafide quasars (the brightest AGN). We have shown, for the first time, based on these direct measurements that these host galaxies reside on the Fundamental Plane and we have determined the MBH-σ relation for these hosts. The Fundamental Plane (FP) is a tight correlation observed for quiescent galaxies in the 3-space defined by the size, brightness and velocity dispersion of the galaxy. Its fundamental nature allows us to empirically relate the observational parameters of galaxies to theoretical models of galaxy formation.
My work has suggested that based on their FP locations, the hosts of radio-loud QSOs evolve through interactions and mergers with nearby galaxies into the largest, most massive quiescent elliptical galaxies observed in large surveys, with a non-negligible fraction of the black-hole mass built-up during later-stage mergers and interactions. Conversely their radio-quiet counterparts evolve into much less massive, quiescent galaxies that may experience a different more secular evolutionary scenario, in which they do not have nearly as strong an interaction history.