I am currently heavily involved in the DEEP2 Redshift Survey, a massive project using the new DEIMOS instrument at Keck Observatory to conduct a census of 50,000 galaxies when the universe was half its current age. DEEP2 began observations at the Keck observatory in mid-2002, and is nearly finished. I am particularly interested in studies which use the large-scale structure observed in DEEP2 to understand the evolution of galaxies over cosmic timescales. DEEP2 data is one component of the multi-wavelength AEGIS survey.
I have recently developed a new method for
calibrating photometric redshifts using large-scale structure
information. Simulations indicate that this method can reach the
precision required by planned dark energy experiments; see this
paper.
I have presented this new method in a number of recent talks; for example see
a PDF
file of a recent talk at Yale University (aimed at a physics audience).
I used the DEEP2 data to test
whether the fundamental physical constants of our universe vary over cosmic timescales
and lengthscales. A webcast of an early talk about this work
from the 2005 Hubble Symposium may be found
here.
I have been spending much of my time the last
few years working with students in Marc Davis' group on DEEP2 papers,
notably Renbin Yan,
Brian Gerke, Michael
Cooper, and Charlie Conroy. I also was heavily involved in
developing the DEEP team's publicly available DEIMOS data reduction
pipeline, which is in wide use. I have also produced a publicly available IDL sample variance /cosmic variance calculator, based on
work published in this
paper. Past projects I have been involved in include:
An up-to-date list of my papers is always
available
at this
site.
'
Analyzing
observations of the optical spectrum of the active galaxy Arp 102B,
which
has been monitored for more than ten years. Arp 102B exhibits a
double-peaked
Balmer broad line spectrum, which may be emitted by an accretion disk
around
a very massive black hole. This work has resulted in a
paper published in The Astrophysical Journal.
I worked
with Steve
Zepf and Marc
Davis,
among others, on a search for Cepheid variable stars in the spiral
galaxy
NGC 4603 (above) within the Centaurus cluster. This is the
most distant galaxy for which the method has been attempted. Such
measurements allow determination of the distance to that cluster, which
is not well known . The resulting paper may be found here. The
Space Telescope Science Institute produced a beautiful image of the
galaxy from our data, which became an Astronomy Picture of the Day; see
here.
With
a similar team, I worked on finding Cepheids NGC 4258 (AKA M106),
a much
closer galaxy whose distance has been independently determined using
the
properties of the maser-emitting disk of gas at its center. This
allows us to test the calibration of the Cepheid distance scale, upon
which
most measurements of distances to other galaxies rely. Two papers
resulted from this work, one in Nature
and one in the Astrophysical
Journal.Investigations of various cosmological tests
which DEEP2 will make possible. From the properties of the
galaxies
found and of the massive clusters made up of these galaxies, it should
be possible to investigate the nature of the "dark energy," an unseen
component
of the universe which appears to dominate its recent evolution.
This
has resulted in three papers, here,
here, and here.
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