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 Luminous
infrared (IR) galaxy mergers (LIRGs) and the host galaxies of Active
Galactic Nuclei (AGN: i.e., accreting supermassive nuclear black
holes) are luminous, dynamically evolving systems in which starbursts
and/or AGN activity have been triggered. The study of LIRGs and AGN is
intimately connected with key extragalactic and cosmological issues
such as the nature of star formation in extreme environments, the
evolution of supermassive nuclear black holes (now believed to reside
in all local massive galaxies), the hierarchical evolution of massive
galaxies, and the nature of the extragalactic submillimeter and x-ray
background. Aaron Evans and his collaborators use a combination
of optical-to-mid IR imaging, millimeter (CO and HCN) spectroscopy,
and near-IR spectroscopy in the study of both low and moderate
redshift LIRGs to ascertain (a) how their starburst and AGN properties
evolve as a function of merger stage, (b) how and when the starburst
and AGN are triggered and fed, (c) their dominant source(s) of
ionization, and (d) how their fundamental structural properties (e.g.,
effective radius and surface brightness) compare with that of their
putative evolutionary byproducts -- i.e., elliptical galaxies and
Quasi-Stellar Objects (QSOs).
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Deane Peterson's interests are currently focused on the use of the
new generation of long baseline Optical Interferometers, specifically
the Navy Prototype Optical
Interferometer (NPOI), to image the disks of stars. Using this
instrument, he and colleagues have resolved the rotationally distorted
disk and specifically the asymmetric intensity distrbution across the
surface of the disk of Altair, one of the three bright A stars making
up the so-called summer triangle. He, along with the same colleagues
have also discovered that Vega, another of the summer triangle and the
principle spectral and photometric standard for Astronomy, is also
rotating near breakup, albeit seen nearly pole-on. This means that
the wavelength dependence of Vega's emitted light will be
substantially different than expected, which will materially affect
its use as a standard.
With planned upgrades, particularly increased baseline lengths,
the NPOI is contributing to opening a whole new chapter in stellar
astrophysics, including how stars accomodate to and evolve while
undergoing extreme rotation, the appearance and evolution of sunspots
on other solar type stars, the appearance of regions of variable
composition on the surface of hotter, but slowly rotating stars, etc.
This is a period of rapid advances, observationally driven, in the area
of stellar astrophysics.
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Mike Simon is interested in the formation of stars, brown
dwarfs, and planets, and more specifically in the processes and
circumstances that govern the formation of binaries and higher order
multiples. At present, he is most involved in using dynamical methods
to measure the masses of young stars to measure the masses of very
young stars with high precision. The goal of this work is to
calibrate calculations of pre-main sequence evolution and thus to
improve the accuracy of mass and age estimates of young stars from
their location in the HR diagram. Increasingly, this work is leading
to similar studies of brown dwarfs.
His research uses state-of-the-art instrumentation in several areas
of astronomy (e.g. IR spectroscopy, adaptive optics imaging, and
interferometry at Gemini and Keck Observatories, mm-wave intererometry
at IRAM). This research is almost always collaborative and offers
students the opportunity to work with instruments at the forefront of
modern astronomy and with scientists who are expert in their use.
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Anand Sivaramakrishnan
and his collaborators helped develop the theory, design and practice of high
contrast coronagraphic instrumentation on 4-8 meter telescopes with "extreme" adaptive optics (ExAO)
systems, constructing and fielding the only such instrument in operation today the
Lyot Project.
They are now searching for companion brown dwarfs and hot young gaseous exoplanets around nearby
bright stars. In addition, they are making coronagraphs for two next-generation ExAO systems on
Palomar and Gemini, with the goal of direct detection and spectral characterization of young,
warm exosolar jovian
planets. Anand and his collaborators pioneered work on the structure and statistics of remnant speckle
noise in well-corrected stellar point-spread functions, and invented methods for coronagraphic
astrometry. This field offers students opportunities in hardware, optics, instrumentation,
developing new observing techniques, and conducting searches for planets and protoplanetary disks
outside our solar system.
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Fred Walter has eclectic interests in galactic astronomy.
His main interests are in star formation in the Galaxy, stellar
coronae and chromospheres, and compact objects. The overarching
theme to his present research is the astrophysics of accretion, from
star formation (T Tauri stars), to white dwarfs (polars and novae).
He is a multiwavelength observer, working in X-rays (Chandra and XMM), UV
(FUSE), optical (HST; SMARTS) and the near-IR (IRTF).
Current projects include
- Accretion and activity in the T Tauri stars S CrA and RU Lupi
- The eruptive pre-main sequence stars (EXORs) V1118 Ori and V1647 Ori
- Spectrophotometry of recent novae, including YY Dor and N LMC 2005
- Coronal structure in rapidly rotating stars: XY UMa and V471 Tau
- Star formation in OB associations, concentrating on the low mass stars
and brown dwarfs in the Orion OB1 association
- properties of isolated neutron stars
- activity cycles in magnetic cataclysmic variables (POLARS)
(image credit: Stella Kafka/CTIO)
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Alan Calder studies a variety of nuclear astrophysics problems as well
as the basic physical processes involved in these problems. He has
investigated core collapse supernovae and coalescing neutron stars,
events thought to be sites of r-process nucleosynthesis, and problems
involving thermonuclear explosions, classical novae and thermonuclear
runaway (Type Ia) supernovae in particular. Calder is also interested
in the challenging problem of radiation hydrodynamics, which has
numerous applications in astrophysics. His research involves
large-scale, multi-physics simulations of astrophysical events, and he
is very interested in the validation of codes and simulations by
comparing simulations to actual laboratory experiments.
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Jim Lattimer studies the structure, composition, formation and
evolution of neutron stars by working at the crossroads between
nuclear theory and astrophysics. He also researches gravitational
collapse supernovae, the mergers of neutron star-neutron star and
neutron star-black hole binaries, and neutrino emission from
proto-neutron stars. He is interested in the nuclear matter equation
of state and the constraints that can be placed on it by laboratory
nuclear measurements as well as by pulsar-timing observations and
optical and X-ray studies of neutron stars. He has published,
and continues to develop, tabulated equations of state that are
frequently used throughout the world in large-scale computational
simulations of supernovae and neutron star mergers.
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 Doug Swesty is
interested in a variety of nuclear astrophysical and
radiation-hydrodynamic phenomena. He is working on neutrino
radiation-hydrodynamic models of stellar core-collapse and type II
supernova explosions. This work utilizes large-scale parallel
computers to carry out high-resolution models of the
neutrino-radiating fluid that is present in prot-neutron stars formed
at the endpoint of the collapse of a massive stellar core. His
research also focuses on the role of the equation of state of hot,
dense matter in facilitating the supernova explosion associated with
the stellar core collapse. Swesty also actively works with colleagues
at national laboratories, such as Lawrence Livermore National
Laboratory, on the development of new radiation transport and
radiation-hydrodynamic algorithms and codes. This includes the
development of verification tests as well as validation testing
strategies using data from high energy density laboratory experiments.
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 Mike Zingale is
interested in understanding astrophysical thermonuclear explosions, in
particular, Type Ia supernovae, Type I X-ray bursts, and Classical
novae. Type Ia supernovae are the largest thermonuclear explosions in
the Universe. The physical processes leading up to the explosion
involve a wide range of length and timescales, making these events
extremely challenging to simulate. Working with colleagues at LBL,
Zingale is involved in the development of low Mach number
hydrodynamics algorithms appropriate to the conditions in these
explosions. These methods filter soundwaves from the system, allowing
for the efficient simulation of long timescale processes, such as
astrophysical convection. Together with other members of the group,
Zingale is interested in verification and validation of astrophysical
hydrodynamics codes.
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