Barry Madore is widely known for his work on Cepheid variables—very bright pulsating stars used to determine distances in the universe—plus his research on peculiar galaxies, and the extragalactic distance scale. He divides his time between directing science for NED, the NASA/IPAC Extragalactic Database, and research at Carnegie. His Carnegie work is to resolve discrepancies between observations of galaxies at different wavelengths, with what is happening during galactic evolution.
Distant and older galaxies appear to be more ragged and disorganized than closer, younger ones. These appearances could be legitimate features, or the effects from the expansion of the universe, which progressively shifts ultraviolet photons from distant galaxies into the range sensed by the optical detectors. Madore is tackling this problem through observations and computer modeling.
To see how the perceived structure changes with wavelength, Madore and Carnegie's Wendy Freedman acquired images of galaxies with the Ultraviolet (UV) Imaging Telescope and compared them with images taken at Las Campanas at optical and near-infrared wavelengths. Even the basic underlying structure was transformed by the particular wavelength used. Rings and bulges, bars and asymmetries come and go depending on use of UV or red wavelenghts. Dust, too, plays a significant role in detection as it scatters and absorbs light.
To model the effects of dust, Madore and colleagues are developing a computer program with a three-dimensional radiative transfer to determine galactic structure at ultraviolet, optical, near-infrared, and thermal-infrared wavelengths. The program uses an innovative technique to compensate for small-particle scattering in the interstellar medium and for behavior in a randomly clumped material, such as a galaxy's spiral arm. The researchers plan to generate images at other wavelengths.
Madore is also a co-investigator on NASA’s GALaxy EXplorer (GALEX) satellite, which is surveying the high-galactic-latitude sky in ultraviolet. It is additionally targeting hundreds of the nearest and largest galaxies for special studies. Unexpected structures (e.g., new sites of star formation) are being discovered in the outermost regions of many previously well-studied galaxies. This work is allowing researchers to better understand the contemporary structure of galaxies and, ultimately, their evolution.
Madore received a B.S. in astronomy and physics from the University of Southern California; an M.Sc. and Ph. D. in astronomy from the University of Toronto. For more information see http://obs.carnegiescience.edu/users/barry