Special Web Supplement

The Dark Side:  Some Web Resources

The strange world of dark matter and dark energy, which together make up some 96% of the Universe, is coming into ever-clearer focus, as astrophysicists employ a variety of observational techniques and instruments to probe the sky's dark side -- and as new missions, telescopes, and other observatories coming on line in the near future promise to enhance our understanding still further. Below, we have collected links to some Web sites that offer glimpses of how scientists are drawing back the veil.

Government Space Science Sites

NASA Structure and Evolution of the Universe Program
Rich and rewarding site laying out NASA strategy for exploring topics related to the origin of the Universe, black holes, and dark energy. Highly recommended.
NASA Space Science
Portal to NASA's astronomy and space science programs includes a full list of links to past, present, and planned missions as well as educational resources.
European Space Agency (ESA) Science
Rich collection of resources on ESA science and missions.
Institute of Space and Astronautical Science (ISAS)
Includes information on a variety of Japanese missions, including some with a dark-side focus, such as ASCA.
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Probing the CMB

Cosmic microwave backgroundThe structure of the cosmic microwave background (CMB) is one of the fundamental constraints on any cosmological model. Gaining an increasingly accurate picture of the patterns of this background radiation will allow scientists to test and further refine assumptions regarding the density and distribution of dark matter, the role of dark energy, and just when the Universe's early "dark age" came to a close.

Selected Space-Based Missions
Cosmic Background Explorer (COBE)
Legendary mission, launched in late 1989, that first established intrinsic anisotropy of the CMB.
Wilkinson Microwave Anisotropy Probe (WMAP)
Handsome site of ongoing NASA mission that is "measuring the temperature of the cosmic background radiation over the full sky with unprecedented accuracy." Site includes a useful educational component, Cosmology 101, an image gallery, and more.
Legacy Archive for Microwave Background Data Analysis (LAMBDA)
Multimission archive that seeks to provide "One Stop Shopping for CMB Researchers." Useful gateway to a variety of other theoretical and experimental sites on the CMB.
European mission, slated for launch in 2007, that will aim squarely at providing CMB maps of unprecedented detail, and at answering questions related to the nature of dark matter.
Sky Polarization Observatory (SPOrt)
Italian instrument, scheduled to be mounted on board the planned International Space Station for 18 months beginning in 2005, will seek evidence for polarization of the CMB.
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Some Ground-Based Instruments and Missions

Following are a few ground-based operations focusing on the CMB. A more complete list can be found at NASA's LAMBDA site.

Cosmic Background Imager (CBI)
Caltech-run radio telescope in the Atacama region, Chile, designed to study CMB radiation properties on angular scales of five arc minutes to one degree.
Degree Angular Scale Interferometer (DASI)
Array of Antarctic radio telescopes, managed by the University of Chicago-based Center for Astrophysical Research in Antarctica (CARA), that in September 2002 reported the first detection of polarization in the CMB.
Array for Microwave Background Anisotropy (AMiBA)
Collaborative Chinese-Taiwanese-Australian venture to build a 19-dish interferometer array focusing on CMB properties. Expected to be completed in 2004.
Arcminute Cosmology Bolometer Array Receiver (ACBAR)
Another Antarctic instrument, jointly managed by U.C. Berkeley and Case Western Reserve University.
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Balloon Missions

High-altitude scientific balloon platforms that ply the skies above the Antarctic have also made a signal contribution to studies of CMB anisotropy. Here are a few prime examples; a more complete list can be found at NASA's LAMBDA site.

MSAM/Top Hat
Remarkably fun and engaging site on one set of late 1990s-early 2000s ballooning missions with a CMB slant. Includes ample tutorial material on cosmology and ballooning, as well as several must-see movies of Top Hat launches.
Maxima balloon inflationMillimeter Anisotropy Experiment Imaging Array (MAXIMA)
Balloon-borne millimeter-wave telescope which, in several flights during the late 1990s, collected data the angular power spectrum of CMB fluctuations over a wide range of angular scales.

Balloon Observations of Millimetric Extragalactic Radiation and Geophysics (BOOMERanG)
Productive multinational project that has produced a number of high-quality CMB maps. Most recent flight, in January 2003, focused on CMB polarization.
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Other CMB Information
The Physics of Microwave Background Anisotropies
Well-known primer on cosmology, CMB, and dark side issues by Wayne Hu of the University of Chicago.
Nice collection of cosmology links.
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Illuminating Black Holes

The best-known objects on the dark side, black holes have received intensive study from a number of celebrated space-borne instruments. Here's a sampling of some current and future missions.

Black-hole jet, seen from HST
Space Telescope Science Institute
The Web site of the Hubble Space Telescope (HST), one of history's nonpareil black-hole finders, is teeming with information and images on a wide variety of astrophysical topics.
Multimission Archive at Space Telescope (MAST)
One-stop data shop for a variety of missions focusing on the near-infrared, optical, and ultraviolet frequency bands.
Chandra X-Ray Observatory Center
Fantastic site of legendary X-ray astronomy "Great Observatory" that has provided a wealth of data not only on black holes but on other denizens of the dark side. Recently released image of the galactic cluster Abell 2029, roughly 1 billion light years from Earth, provided "the most detailed probe yet of the distribution of dark matter in a massive cluster of galaxies."
XMM-Newton (ESA)
European X-ray observatory launched in 1999 has made a number of contributions to understanding black holes and other dark phenomena.
Integral (ESA)
Gamma ray probe providing new insights on supermassive black holes, neutron stars, and other exotic objects.
NASA "vision mission," slated for possible launch in 2011, that will deploy four 1.6-meter space-borne X-ray telescopes used as an array. The result could be a 100-fold increase in resolution compared with existing instruments, which in turn could allow unprecedented observations of black holes, baryonic dark matter, and large-scale structure back to the earliest moments in the Universe's history.
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Supernova Observations and Modeling

Observations of type Ia supernovae have played a pivotal role in establishing that some 70% of the mass-energy content of the Universe consists of dark energy, the mysterious "antigravity" that is causing the expansion of the Universe to accelerate. Supernovae observations, at increasingly fine scales and large distances, remain a key testbed for ideas about just what dark energy is.

Supernova Teams and Projects
High-Z Supernova Search
International group of astronomers seeking type 1a supernovae at high redshifts, and using those data to "trace the expansion of the Universe from the present day to 9 billion years in the Past." One of the groups (along with Supernova Cosmology Project) that uncovered evidence that expansion of the Universe is accelerating.
Supernova Cosmology Project
Another international collaboration focusing on supernova studies and their implications for dark energy. Responsible (along with High-Z Supernova Search team) for first evidence that the Universe is expanding at an accelerating rate, powered by dark energy.
ESSENCE (Equation of State: SupErNovae trace Cosmic Expansion)
Project of the Cerro Tolodo Inter-American Observatory to track 200 type 1a supernovae over five years in order to pin down w -- the key adjustable parameter in the "equation of state" of the Universe.
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Supernova Missions/Telescopes with CCDs

The installation of high-resolution charged coupled detectors (CCDs) on terrestrial and spaceborne telescopes is revolutionizing our ability to see deep into the cosmos. Over the next several years, these deep-field observatories promise a new generation of sharp images that should dramatically expand the supernova catalog, and allow new insights on dark energy. In addition, as noted in a news article by R. Irion in Science's 20 June 2003 special issue, many of the same cameras will provide the key to microlensing experiments that should help provide a much better census of the Universe's dark matter as well.

Great Observatories Origins Deep Survey (GOODS)
Plan to survey the deep sky, including distant supernovae, by combining Hubble Space Telescope deep-field observations (reimaged using the high-resolution Advanced Camera for Surveys recently installed on the HST) with deep-field observations from two other Great Observatories, the Chandra X-ray Observatory and the Space Infrared Telescope Facility (SIRTF) slated for launch in 2005, as well as from the ESA's XMM-Newton spacecraft.
Supernova Acceleration Probe (SNAP)
Proposed spaceborne mission that would devote 32 months to supernova searches and five months to weak gravitational lensing surveys. The project's planners believe that the observatory could boost the discovery rate of distant supernovae to some 2,000 per year over its three-year life span.
The largest astronomical camera ever built, installed on the 3.6 meter Canada-France-Hawaii Telescope, this instrument will play a key role in the CFHT Legacy Survey, which will include wide and deep synoptic surveys with goals such as imaging of hundreds of new supernovae and measuring weak gravitational lensing.
Subaru Telescope
Facility of the National Astronomical Observatory of Japan located on Mauna Kea, Hawaii, and featuring the Suprime-Cam mosaic of ten CCD imagers.
Large-aperture Synoptic Survey Telescope (LSST)
Proposed enormous (8.4 m) survey telescope, covering a 7 degree square field, that is expected to begin observations early in the next decade.
Some other deep-space observatories focusing on supernovae, dark matter, and dark energy:
Mosaic I and Mosaic II CCD Imagers at CTIO
Keck Observatory
Very Large Telescope
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Other Supernova Information
Supernova and Supernova Remnant Pages on the WWW
Very nice, well maintained selection of links by Marcos Montes of the Naval Research Laboratory's Remote Sensing Division.
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Evidence from Luminous Sources

The Two-Degree Field (2dF) System
This long-running spectrographic survey of part of the southern sky uses the Anglo-Australian Telescope in Australia to record redshifts of 220,000 galaxies and 23,000 quasars.
The Sloan Digital Sky Survey
Web site of "the most ambitious astronomical survey project ever undertaken," covering a quarter of the sky.
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Looking for Dark Matter on Earth

On the Trail of WIMPs

In addition to searching the skies, astrophysicists and particle physicists are going to great lengths -- and depths -- to find evidence on Earth for the dark matter that pervades the Universe. Among the most sought-after candidates are particles of so-called cold dark matter known as weakly interacting massive particles, or WIMPs. Many of the WIMP detection efforts are located at the same facilities that are celebrated for efforts to collect another well-known, proverbially elusive particle, the neutrino. Following are some links relevant to the search for WIMPs.

WIMP Direct Detection Overview
Readable late-2002 review article by Y. Ramachers (posted at the arXiv.org preprint server) that outlines the methods to detect WIMPs and their progress thus far.
Some WIMP detection projects:
In Boulby, U.K.:
U.K. Dark Matter Collaboration
Directional Recoil Identification From Tracks (DRIFT)
ZEPLIN Dark Matter Search
In Soudan, Minnesota, U.S.:
Cryogenic Dark Matter Search (CDMS)
In Gran Sasso, Italy:
DAMA Experiment
Cryogenic Rare Event Search with Superconducting Thermometers (CRESST)
In Canfranc, Spain:
Rare Objects SEarch with Bolometers UndergrounD (ROSEBUD)
Frejus, France:
In Sudbury, Canada:

Other Dark Matter Searches (from UKDMC site)

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Neutrino Experiments

Once among the prime candidates for making up the bulk of the Universe's dark matter, neutrinos -- classified as "hot" dark matter -- are no longer thought to constitute a large share of the stuff: Their extremely high, relativistic velocities in the Universe's early years would have kept them from settling down into the large-scale cosmic structures implied by the clumpy, anisotropic CMB. Nonetheless, a variety of interesting problems related to neutrinos remain; below are some links to important neutrino observatories.

Some key neutrino observatories:

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Dark Matter from Colliders

Another avenue toward learning about what makes up dark matter should lie in the high-energy interactions that will be possible in the next generation of accelerators and colliders. Here are links relevant to some of those projects. (For more on the next generation of colliders, see Adrian Cho's News Focus in the 21 February 2003 issue of Science.)

Some large collider/accelerator projects and relevant sites:

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Searching for Gravity Waves

Gravity waves, predicted by general relativity but not detected thus far, have the potential to let scientists probe earlier even than the time represented by the CMB. Following are a number of missions and projects aimed at detecting and studying gravity waves.

Laser Interferometer Space Antenna
Handsome NASA site describing gravity-wave mission aimed for 2011 launch. A companion ESA site also includes useful information.
Laser Interferometer Gravitational Wave Observatory
Ground-based interferometer that will employ two widely spaced sites (one in Hanford, Washington; the other in Livingston, Louisiana) as a single gravity wave observatory.
Japanese laser interferometer gravitational wave antenna that began operation in 2002 and continues to take data.
Italian-French collaboration to build and deploy a large laser interferometer to study gravity waves.
Australian International Gravity Observatory, being constructed near Perth.
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Modeling Star Formation

Models of star formation, and particularly of formation of the very first star, bear significantly on our understanding of how and when the Universe's "dark age" finally came to a close. Included below are some links to pages related to individual star formation models. For a more comprehensive set of resources on star formation, see the Web supplement to Science's 4 January 2002 special issue on the subject.

Some pages related to star formation models:

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Miscellaneous Resources

Organizations and Associations
Preprints and Reprints
Space News Portals
Web Directories
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