Fall 2013 Recipients
Michael A. Troxel
Prof. Mustapha Ishak
The 2013 Robert S. Hyer Research Award of the TSAPS will be awarded to Michael Troxel and Prof. Mustapha Ishak from the University of Texas at Dallas for their work on Cosmic Shear.
Michael’s Ph.D. thesis research concerns theoretical studies of gravitational lensing by the large-scale structure of our universe. The large-scale structure is like a massive cosmic web; mass along the line of sight to distant galaxies distorts space-time around it, as predicted by Einstein’s General Theory of Relativity. This results in the deflection of light rays from distant galaxies and leads to tiny distortions in the observed shapes of these galaxies. This cosmic shear signal is manifest in statistically correlated shapes of galaxies that are close on the sky (since their light travels past similar parts of the cosmic web) with the correlation falling off for galaxies that are more widely separated. The great importance of cosmic shear is that it allows access to information on dark matter and dark energy in the universe; the cosmic web itself is primarily dark matter. In addition, the amount and properties of dark energy are imprinted on the growth of the cosmic web from the tiny mass fluctuations present at earlier times. Michael’s thesis research addresses a very critical aspect of harnessing cosmic shear as a cosmological tool. The Dark Energy Task Force of Albrecht et al. identified cosmic shear as the most promising way to study dark energy, which is thought to dominate the mass-energy density of the universe. One of the most important systematics arises from the intrinsic alignments of galaxies: galaxies formed near each other in a similar tidal gravitational field tend to have similar shapes. This intrinsic alignment signal and the cross-term with cosmic shear must be dealt with, since it contaminates the measurement of cosmological parameters.
Prof. Ishak-Boushaki is, well known in the cosmology community, prolific in his publications, especially jointly with his students. He is a very successful and conscientious mentor who, in some magical way, he carves out large chunks of time to spend with his students, in spite of the many other demands on his time.
 Large-Scale Growth Evolution in the Szekeres Inhomogeneous CosmologicalModels with Comparison to Growth Data
Peel A., Ishak M. & Troxel M.A. Physical Review D, 86, 123508, December 2012.
 Self-calibrating the gravitational shear-intrinsic ellipticity-intrinsic ellipticity (GII) crosscorrelation
Troxel M.A. & Ishak M. Monthly Notices of the Royal Astronomical Society, 427, 441, November 2012.
 xSelf-Calibration for 3-point Intrinsic Alignment Auto-Correlations in Weak Lensing Surveys
Troxel M.A. & Ishak M. Monthly Notices of the Royal Astronomical Society, 423, 1663, May 2012.
 Self-Calibration Technique for 3-point Intrinsic Alignment Correlations inWeak Lensing Surveys
Troxel M.A. & Ishak M. Monthly Notices of the Royal Astronomical Society, 419, 1804, January 2012.
 Comparative Direct Analysis of Type Ia Supernova Spectra. IV. Postmaximum Branch D., Jeffery D.J., Parrent J., Baron E., Troxel M.A., Stanishev V., Keithley M., Harrison J. & Bruner C. Publications of the Astronomical Society of the Pacific, 120, 135, August 2008. doi:10.1086/527572
 Comparative Direct Analysis of Type Ia Supernova Spectra. III. Premaximum Branch D., Troxel M.A., Jeffery D.J., Hatano K., Musco M., Parrent J., Baron E., Dang L.C., Casebeer D., Hall N. & Ketchum W. Publications of the Astronomical Society of the Pacific, 119, 709, July 2007. doi:10.1086/520553
 Direct Analysis of Spectra of the Unusual Type Ib Supernova 2005bf Parrent J., Branch D., Troxel M.A., Casebeer D., Jeffery D.J., Ketchum W., Baron E., Serduke F.J.D. & Filippenko A.V. Publications of the Astronomical Society of the Pacific, 119, 135, February 2007. doi:10.1086/512494
 Comparative Direct Analysis of Type Ia Supernova Spectra. II. Maximum Light Branch D., Dang L.C., Hall N., Ketchum W., Melakayil M., Parrent J., Troxel M.A., Casebeer D., Jeffery D.J. & Baron E. Publications of the Astronomical Society of the Pacific, 119, 135, April 2006. doi:10.1086/502778
 Probing the Nature of Type I Supernovae with SYNOW Branch D., Parrent J., Troxel M.A., Casebeer D., Jeffery D.J., Baron E., Ketchum W. & Hall N. AIP Conference Proceedings, 924, 342, August 2007. doi:10.1063/1.2774879
 Cosmology in the Era of Big Surveys, Invited Colloquium Talk, Southern Methodist University, Dallas, TX, March 2013
 Intrinsic Alignment of Galaxies and 3-point Self Calibration, 221st AAS Meeting, Long Beach, CA, January 2013
 Intrinsic Alignment of Galaxies and Self-Calibration, Texas Section APS Meeting, Texas Tech University - Lubbock, TX, October 2012
 Self-Calibration Technique for 3-point Intrinsic Alignment Correlations in Weak Lensing Surveys, 219th AAS Meeting, Austin, TX, January 2012
 Intrinsic Alignment and GGI Self-Calibration, Texas Section APS Meeting, Texas A&M University - Commerce, Commerce, TX, October 2011
The 2013 Hyer Award for undergraduate research was awarded to Nalin Ranayeke and Prof. Vernita Gordon, both from the University of Texas at Austin. Nalin is a double major working on a Physics and Biology degree at the Center of Nonlinear Dynamics at UT-Austin. He has been working with Dr. Gordon since September 2011. His project is about the cellular response to mechanical changes and how this behavior relates to cancer. In his research project Nalin works with human cell cultures and has learned to work with aseptic techniques, microscopy, and various imaging analysis techniques. His honors include eight scholarships and awards including the Dr. H. Franklyn Alexander Endowed Scholarship, and the Walter E. Millet Endowed Undergraduate Scholarship in Physics.
Prof. Dr. Gordon joined the University of Texas in 2010. She received a B.Sc. Degree in Physics and Mathematics from Vanderbilt University and a PhD. in Physics from Harvard. She has set up a flourishing Biophysics group at UT-Austin and is well published. For more information on her work see the references listed below [2, 3, 4].
Publications and presentations:
 Nalin Ranayeke, Vernita Gordon, Oral presentation TSAP Fall-2013 meeting, Brownsville, Texas.
The extracellular polysaccharide Pel makes the attachment of P. aeruginosa to surfaces symmetric and short-ranged. B.J. Cooley, T.W. Thatcher, S.M. Hashmi, G. L’Her, H.H. Le, D.A. Hurwitz, D. Provenzano, A. Touhami, V. D. Gordon, 2013 Soft Matter 9:3871-3876.
 Flagella and pili-mediated near-surface single-cell motility mechanisms in P. aeruginosa. J.C. Conrad, M.L. Gibiansky, F. Jin, V. D. Gordon, D.A. Motto, M.A. Mathewson, W.G. Stopka, D. C. Zelasko, J.D. Shrout, G.C.L. Wong, 2011, Biophysical Journal 100: 1608-1616.
 Bacteria use type IV pili to walk upright and detach from surfaces. Gibiansky, M.L., Conrad, J.C., Jin F., Gordon, V.D., Motto, D.A. Mathewson, M.A., Stopka, W.G., Zelasko, D.C. Shrout, J. D., Wong, G.C.L., 2010 Science 330:197.