Image from the Hubble Space Telescope

Physics Faculty : Nahum Arav; Duncan Farrah; John Simonetti
Physics Emeriti Faculty : John Broderick; Brian Dennison
ECE Faculty: Steven W. Ellingson; Cameron Patterson
Research Scientists : Sara Petty

The astronomical sciences group at Virginia Tech is active in studies of: transient phenomenon at radio wavelength (including possible signature for exploding primordial black holes); influence of super massive black holes on structure formation in the universe, observational studies of quasars and Seyfert galaxies; and the interstellar medium (ISM).

Research facilities we are using include: the Hubble space telescope; the largest ground based optical telescopes (VLT, Subaru and Keck); the Very Large Array (VLA) and the Very Long Baseline Array (VLBA) radio telescopes. We operate our own Spectral Line Imaging Camera (SLIC) in current use for the Virginia Tech Spectral-Line Survey.

Hubble Space Telescope

The Hubble Space Telescope in orbit around the Earth

Arav's s group is working on determining the influence of super massive black holes on structure formation in the universe. They do so by observing outflows emanating from the vicinity of the black holes and determining the physical characteristics of these outflows. In particular, the group is concentrating on measuring the kinetic energy of these winds since this is the single most important parameter in assessing their influence on the galactic and intergalactic environments. The work includes observing such outflow using ground based optical telescopes, measuring the different ions that comprise the outflow and performing photoionization modeling to extract the physical conditions in the outflow.

Arav's s group is also working on the connection between the Ultraviolet and X-ray manifestation of the so called "warm absorbers" in Seyfert galaxies. This is done by acquiring and analyzing Ultraviolet and X-ray spectra of these objects using the Hubble space telescope and the Chandra X-ray satellite. The chemical abundances in these objects is also of great interest to the group.

Simonetti and Dennison have a long-standing interest in the interstellar radio-wave scattering seen toward extragalactic radio sources. The observation and interpretation of the scattering of radio waves from compact sources provide a unique probe of the structure of the ISM at very small scales. Simonetti has also probed irregularities in the ISM through observations of variations in interstellar Faraday rotation (seen toward extragalactic sources).

Simonetti and Dennison are also currently engaged in an optical survey of ionized interstellar gas seen over the northern hemisphere utilizing a sensitive, wide-field, digital (CCD) camera system equipped with narrow-bandpass filters (e.g., an H-alpha interference filter and a [SII] filter). In addition to the survey, observations are being made of selected fields of special interest. The results bear upon studies of radio wave scattering, general ISM phenomena, and searches for small-scale anisotropies in the microwave background radiation produced in the Big Bang. The Virginia Tech Spectral-Line Survey (VTSS) webpage contains details on the project, discussion of current results, and information on SLIC.

ETA Core Array at PARI
The ETA Core Array at the Pisgah Astronomical Research Institute in North Carolina.

Simonetti, in collaboration with faculty in the Department of Electrical and Computer Engineering (Professors Steve Ellingson and Cameron Patterson), is constructing an antenna array designed to continuously monitor virtually the entire northern sky for short bursts of radio emission (radio transients) from high-energy astrophysical phenomena, potentially including gamma ray bursts, supernovae, mergers of compact objects, the explosion of primordial black holes, and giant pulses from pulsars. The project is call ETA for "Eight-meter-wavelength Transient Array." The array is being constructed at a remote site in western North Carolina. The ETA website contains more details on the project. See also, the following articles:

Simonetti and Ellingson are also official representatives for Virginia Tech on the US Consortium for the Square Kilometer Array (SKA), an international project to design and build a radio telescope for the 21st century.

ETA team photo

The ETA project team:
Profs. Simonetti (standing, left)
Ellingson (standing, right)
and Patterson (seated).
Photo by John McCormick
March 20, 2006.

The VTSS project is funded by the NSF Division of Astronomical Sciences, AST-9319670, AST-9800476, and AST-0098487, and by the Horton Foundation. The ETA project is funded by the NSF Division of Astronomical Sciences, AST-0504677.

Undergraduate Astronomy Minor

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Virginia Polytechnic Institute & State University 
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