UTB/TSC Department of Physics & Astronomy

Faculty and students are engaged in fundamental research in relativistic astrophysics, gravitational wave astronomy, biophysics, nanoscience, and optics.

Nanoenergetic systems also known as metastable intermolecular composites (MIC) have various potential applications as propellants, explosives, and primers. The development of novel MIC systems, their design, synthesis and fabrication procedures are critical for national security and it was recognized as a significant addition to support of changing force structure for advanced weapons platforms. Our research at UTB focuses on developing a framework of principles for design and fabrication of nano-tailored highly energetic systems and nanoenergetic gas generators (NGG) for advanced energetic platforms. This involved a systematic study of physics based knowledge in energy release, shock waves and pressure discharge needed to enhance the performance and functionality of novel high density energetic systems.
Read article...

Galaxies appear simpler than before by Disney et al. The image shows a montage of coloured images of a dozen galaxies (huge whirlpools of stars in space) drawn from our survey of the universe, which is the subject of the letter. As well as being very beautiful they have considerable scientific interest too because they show a wider variety of galaxies than it has been possible to portray before. Hitherto galaxies were found optically, and hence tended to look rather like one another. These, however, were picked up in a radio survey and imaged only afterwards. Consequently they exhibit a much wider range of colours, shapes and surface brightnesses. Intriguingly some of them, although close-by in cosmic terms, are almost, but not quite, invisible. We believe both astronomers and laymen will find them fascinating. Copyright belongs to one of the co-authors, Andrew West. Read article...

Although predicted by S. Rytov more than sixty years ago the experimental proof that radiative heat transfer can be exponentially improved by reducing the gap between two surfaces of different temperature was only recently demonstrated for macroscopic objects with a geometry that can be compared with theoretical predictions. The scientists from the University of Florida and the University of Texas at Brownsville demonstrated good agreement between theoretical prediction and measurement. When an infinite warm surface is separated from a cooler one by a vacuum gap, the rate of radiative heat transfer between the two shouldnt depend on the size of the gap. According to theory, though, this picture doesnt hold when the surfaces are sufficiently close. In the paper "Near-Field Radiative Heat Transfer between Macroscopic Planar Surfaces" (Phys. Rev. Lett. 107, 014301, 2011), the scientists focused on a straightforward planar geometry. The heat transfer between two parallel square sapphire plates, each about two inches on a side, was measured for separations from a 0.1 mm down to only a few microns. A pronounced increase in heat transfer is seen as the gap between the plates is reduced following the theoretical predictions. In principle, near-field heat transfer could be used to control the temperature of an object without ever contacting it. This is an interesting possibility for cooling the sensitive mirrors in future gravity wave detectors.

Using recent data from the LIGO interferometers, LIGO scientists have been able to constrain the fractional energy density in gravitational waves to < 6.9 x10^-6 (at 95% confidence) in a ~100 Hz band around 100 Hz. This number improves on indirect limits on the gravitational wave background obtained from the relative abundance of light elements in the very early universe (Big Bang Nucleosynthesis). The attached figure shows various limits on the gravitational wave background and predictions from three different models (inflation, pre-Big Bang cosmology, and cosmic strings). The indirect limits are from Big Bang Nucleosynthesis and the Cosmic Microwave Background; the direct limits are from the LIGO S4 and S5 science data (see attached paper), and from pulsar timing data. Projected limits from the advanced LIGO detectors, the CMB Planck satellite mission, and the proposed space-based interferometer LISA are also shown. More...