Cosmic Microwave Background (CMB) Research: Studies of the CMB
from space have produced ground-breaking results on the conditions in
the early universe. The CMB research group in LASP led the COBE mission
(including the Project Scientist, Principal and Deputy Investigators of
the FIRAS and DIRBE instruments, and Deputy PI for the DMR instrument).
The WMAP mission
is a collaborative project between GSFC/LASP and
Princeton University to map the microwave sky at 44 times the
sensitivity and 33 times the angular resolution (13 arcmin) of COBE.
Scientific papers from the first year of operation were published in a
special issue of the ApJ, and included such results as: (1) full sky
maps of the temperature anisotropy, (2) constraints on models of
structure formation, the geometry of the universe and inflation, (3)
detection of reionization after the Dark Ages, (4) accurate values of
many cosmological constants, and (5) initial results on the
polarization of the CMB. WMAP is still operating and taking high
quality data. Results from the first 2 full years of data will be
released in 2004. The CMB group in LASP includes Bennett, Fixsen
(SSAI), Hill (SSAI) Hinshaw, Kogut, Limon (SSAI), Mather, Mirel (SSAI),
Moseley, Odegard (SSAI), Weiland (SSAI), and Wollack.
Kogut (PI), Fixsen, Limon, Mirel, and Wollack of LASP, in collaboration
with Levin (JPL), Seiffert (JPL), and Lubin (UCSB) launched the Absolute
Radiometer for Cosmology, AStrophysics, and Diffuse Emission (ARCADE), a balloon-borne
instrument to measure the spectrum of the CMB at centimeter wavelengths.
ARCADE searches for the signature of heating from the first generation
of stars to form after the Big Bang. Successful flights in 2001 and 2003
showed the CMB to follow a blackbody spectrum down to 3 cm wavelength.
A second-generation instrument is under construction and will launch in
2005.
Recently, Kogut (PI), Fixsen, Hinshaw, Limon, Moseley, Wollack (all
LASP), Devlin (U Penn), and Irwin (NIST) were awarded a NASA/ROSS grant
to fly a high-altitude balloon payload (PAPPA) to measure the
polarization anisotropy of the CMB. The flight will search for the
imprint of gravity waves produced during an inflationary epoch in the
early universe and also characterize the polarized Galactic foregrounds.
Hinshaw (PI) leads a mission concept study for the Inflation Probe (aka
CMBPOL), one of the Einstein Probes in the "Beyond Einstein" initiative
in NASA's Structure and Evolution of the Universe theme. The goal of
the inflation probe is to measure the amplitude of the B-mode
polarization in the early universe, as direct support for the Inflation
theory and to measure of the energy scale of Inflation.
Hinshaw (PI) is the Director of the Legacy Archive for Microwave
Background Data Analysis
(LAMBDA)
Data Center, which strives to provide
one-stop shopping for the CMB research community.
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Wide-Field Imaging Interferometry Testbed (WIIT):
LASP members Leisawitz, Danchi, Mather, Rinehart, Gezari and Moseley (685)
(along with co-investigators from UMd, JPL, and NRL)
are developing WITT in support of design studies
for NASA's future space interferometry missions, in particular the SPIRIT
(SPace InfraRed Interferometric telescope) and
SPECS (Submillimeter
Probe of the Evolution of Cosmic Structure) far-infrared/submillimeter
interferometers. WIIT operates at optical wavelengths and uses Michelson
beam combination to achieve both wide-field imaging and high-resolution
spectroscopy. It will be used chiefly to test the feasibility of using a large-
format detector array at the image plane of the sky to obtain wide-field
interferometry images through mosaicing techniques. In this setup each
detector pixel records interferograms corresponding to averaging a particular
pointing range on the sky as the optical path length is scanned and as the
baseline separation and orientation is varied. The final image is constructed
through spatial and spectral Fourier transforms of the recorded
interferograms for each pixel, followed by a mosaic/joint-deconvolution
procedure of all the pixels. In this manner the image within the pointing
range of each detector pixel is further resolved to an angular resolution
corresponding to the maximum baseline separation for fringe measurements.
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Development of far-IR detectors: Moseley, Benford, Shafer (685) are
engaged in developing detectors for the
12x32 array of doped silicon pop-up bolometers, developed by Moseley et al
at GSFC, cooled with He to 0.3 K. FIBRE (Fabry Perot Interferometer
Bolometer Research Experiment) is a scanning Fabry Perot (R~1000) cooled
to 1.5K for observation in the 350-450 micron window. LASP is
responsible for the detectors, cryostat, and data acquisition interface with
CSO. FIBRE is shown at left in the lab at LASP. Installation of
SHARC-II at CSO is shown on the right. SHARC-II is being developed
jointly by LASP/GSFC and Caltech. FIBRE collaborators include several
institutions in France, LASP/GSFC and Caltech.
