Susan A Lamb

Biography

Professor Susan Lamb received her bachelor's degree in physics and applied mathematics from Queen Mary College, London University, in 1969 and her D. Phil. in astrophysics from Oxford University in 1973. She is presently an associate professor of Physics and of Astronomy at the University of Illinois.

A theoretical and observational astrophysicist, Susan Lamb research interests are in extragalactic astronomy. She has studied interacting and colliding galaxies and focused on the consequences for global star formation and the evolution of galaxies, as well as the triggering of active galactic nuclei (AGN) and the evolution of ‘dark matter’ halos around galaxies. This work has involved both computational studies using national supercomputers, and collaboration with other investigators in obtaining and interpreting observations of colliding galaxies. She has now embarked on a computational study of colliding galaxies that will include a full representation of the temperature structure of the interstellar gas, as well as the possibility of following the chemistry in the gas as galaxies collide, merge, and evolve. This allows a direct comparison between the predictions of collision simulations and a range of observations of colliding and merging systems, such as observations of the hot (million degree) phase of the interstellar gas, as obtained from the NASA Chandra X-ray Observatory, optical observations of star-forming regions from the Hubble Space Telescope and ground-based telescopes, and 21-cm radio observations of neutral hydrogen. The ultimate goal of this work is to link the outcome of collisions and mergers of galaxies to the evolution of galaxies and the history of star formation in the Universe; to the redistribution of ‘dark matter’ in clusters and groups of galaxies; and to examine the contribution of these processes to the generation of the million-degree gas observed to exist around some galaxies and to dominate emission from clusters of galaxies.

Research Statement

Global Star Formation in Impact-induced Starburst Galaxies
The first impact of two colliding galaxies takes place on a time scale of approximately 10^8 years, the dynamical time scale. Within this period it is anticipated that much star formation will be triggered as a result of density increases and shocks in the gas which are produced by inflow to the nuclear regions. We are currently comparing our array of simulations of galaxy collisions to observations of collisionally produced starburst galaxies (both our own observations and those of others) and investigating the resulting implications for both the stellar and gaseous components.

Active Galactic Nuclei, Dense Stellar Systems, and Galactic Environment
We are investigating a self-consistent model on a large range of scales to understand the processes leading to nuclear activity in galaxies. Current observations support the view that interactions between galaxies may be crucial in triggering episodes of activity in some active galactic nuclei. Interactions also trigger some starbursts, and we are investigating the relationship between these two phenomena. We employ numerical simulations of colliding galaxies and analytical studies of the physics of the central regions of galaxies to obtain a detailed model that can be compared to observations of these systems.

Selected Articles in Journals

• L. M. Young, E. Rosolowsky, J. H. van Gorkom, and S. A. Lamb. The evolution of the interstellar medium in the mildly disturbed spiral galaxy NGC 4647. Astrophysical Journal, 650:1 Part 1, 166-179 (2006).
• S. A. Lamb and N. C. Hearn. Collisions and mergers of disk galaxies: Hydrodynamics of star forming gas. Astrophys. & Space Sci. 284, 479-482 (2003).
• J. C. McDowell, et al. Chandra observations of extended X-ray emission in Arp 220. Astrophys. J. 591, 154-166 (2003).
• D. L. Clements, et al. Chandra observations of ARP 220: The nuclear source. Astrophys. J. 581, 974-980 (2002).
• N. C. Hearn and S. A. Lamb. ARP 119: A high-speed galaxy collision with episodic star formation. Astrophys. J. 551, 651-670 (2001).