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