Department of Astronomy Center for Radiophysics & Space Research

Robin Garrod

Senior Research Associate
Robin Garrod

Dr. Garrod investigates the chemistry that takes place in the interstellar medium (ISM) and in star-forming regions. In particular, Dr. Garrod is interested in the formation of highly complex molecules in the ISM. He has developed coupled gas-grain chemical models of hot molecular cores in star-forming regions, which simulate the formation and destruction of molecular matter, right up to the most complex organic molecules yet detected. He was recently a member of the team that discovered ethyl formate (C2H5OCHO) and n-propyl cyanide (C3H7CN) - the largest molecules yet discovered in star-forming regions. Dr. Garrod is also undertaking a combined observational and computational research effort to understand how the changing temperature and density conditions of the star-formation process control the abundances, spatial extents and rotational temperatures of molecules observed in hot molecular cores.

Dr. Garrod is currently working in collaboration with surface scientists at the University of Leiden, Netherlands, to simulate interstellar ice photochemistry in the laboratory, and to quantify the underlying physical and chemical processes that lead to the formation of complex organic molecular structures, using detailed chemical modeling. This work will yield fundamental physical and chemical data, allowing the experimental results to be accurately extrapolated to the low-flux/long-timescale environments of the interstellar medium.

Dr. Garrod is also active in the development of numerical techniques that simulate interstellar chemistry. The chemistry that occurs on the surfaces of interstellar dust grains is inherently stochastic, and therefore difficult to couple with deterministic gas-phase chemistry. Dr. Garrod has recently published a new method that accurately traces the chemistry in both phases with minimal computational effort. This allows efficient simulation of the most complex chemical networks, under the variable physical conditions and long timescales that obtain in the interstellar medium.

Selected Publications
  • A New Modified-Rate Approach For Gas-Grain Chemistry: Comparison with a Unified Large-Scale Monte Carlo Simulation. R. T. Garrod, A. I. Vasyunin, D. A. Semenov, D. S. Wiebe, and Th. Henning, 2009, ApJL, 700, 43.
  • Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate and n-propyl cyanide in Sagittarius B2(N). A. Belloche, R. T. Garrod, H. S. P. Mueller, K. M. Menten, C. Comito, and P. Schilke, 2009, A&A, 499, 215 (arXiv:0902.4694).
  • A new modified-rate approach for gas-grain chemical simulations. R. T. Garrod, 2008, A&A, 491, 239 (arXiv:0809.2934).

Complex Chemistry in Star-forming Regions: An Expanded Gas-Grain Warm-up Chemical Model). R. T. Garrod, S. L. Widicus Weaver, and E. Herbst, 2008, ApJ, 682, 283 (arXiv:0803.1214).

Non-thermal desorption from interstellar dust grains via exothermic surface reactions. R. T. Garrod, V. Wakelam, and E. Herbst, 2007, A&A, 467, 1103 (arXiv:0703.3188).

Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores. R. T. Garrod, and E. Herbst, 2006, A&A, 457, 927 (arXiv:0607560).