Dark Energy: Shaping Our Tools

by Paul Gilster on January 30, 2008

Can measuring the positions and velocities of thousands of galaxies provide insight into the nature of dark energy? If so, we may have found a way to study what is perhaps the most puzzling question in astrophysics, the discovery that the expansion of the universe is proceeding faster today than it did in the past. Armchair theorists love dark energy because we know so little about it, and I routinely get e-mails offering to tell me exactly what dark energy is, few of which have any bearing on current observation or theory.

But that’s the way of mysteries — they incite comment — and as mysteries go, dark energy is a big one, perhaps the biggest now stirring the astrophysical cauldron. If we assume a dark energy producing a check on the gravitational pull of all matter in the cosmos, we’ve got the attention not just of cosmologists but propulsion theorists, who would love to find out how such a repulsive force might work. And if there is no such thing as dark energy, then determining why should tell us much about where and how we need to tweak current theories of gravitation, which also may have propulsion implications.

The European Southern Observatory’s Very Large Telescope array is at the heart of the latest dark energy work, looking at redshift distortions of distant galaxies by the thousands. The work relies on the fact that the expanding universe pushes galaxies away from each other, even as gravity tries to pull them together. Olivier Le Fevre, a member of the large international team behind this study, focuses on its technique:

“By measuring the apparent velocities of large samples of galaxies over the last thirty years, astronomers have been able to reconstruct a three-dimensional map of the distribution of galaxies over large volumes of the Universe. This map revealed large-scale structures such as clusters of galaxies and filamentary superclusters. But the measured velocities also contain information about the local motions of galaxies; these introduce small but significant distortions in the reconstructed maps of the Universe. We have shown that measuring this distortion at different epochs of the Universe’s history is a way to test the nature of dark energy.”

With thirteen thousand spectra in a field of view twenty times the size of the full Moon now available, the team can compare its result to the 2dF Galaxy Redshift Survey of the ‘local’ universe, assessing what the comparison tells us about dark energy. What seems to be emerging thus far is a confirmation of the technique, which will now require a set of future measurements to be extended over an area ten times larger than the current field. We are, in other words, still at the point of shaping our tools, and unable to make the definitive call on dark energy vs. competing explanations for what we observe. But shaping our tools is simply part of the necessary and painstaking preliminaries that make all science work.

The paper is Guzzo et al. (and I do mean ‘et al.,’ as there are 51 authors listed!), “A test of the nature of cosmic acceleration using galaxy redshift distortions,” Nature 451 (31 January 2008), pp. 541-544 (abstract). Also be aware of Strauss, “Cosmology: An ancient view of acceleration,” in the same issue (more on this one when I have time to study it).

{ 18 comments }

ljk January 30, 2008 at 16:00

Galaxy distortions shed light on cosmic acceleration

Physics World

http://physicsworld.com/cws/article/news/32648

Matthew Chalmers

Matthew Chalmers is a science journalist based in the UK

January 30, 2008

This time ten years ago, two independent teams of researchers
in the US were deliberating over whether to go public with a
discovery that would change our view of the universe forever.
It concerned observations of distant supernovae that appeared
to be moving away from each other faster than they should have
been. A few weeks later the world found out that the expansion
of the universe is accelerating, probably driven by some kind of
gravitationally repulsive “dark energy” that makes up 75% of
the universe.

Fast-forward a decade and physicists still have no idea what
dark energy is….

Researchers get a handle on cosmic dynamics by studying the
rate at which galaxies fly apart, which comes down to measuring
how much their light has been “red-shifted” to longer wavelengths.

When Edwin Hubble showed in 1929 that the red-shift of distant
galaxies is proportional to their distance from Earth, it proved
that the universe was expanding. The same principle underpinned
the 1998 discovery that the expansion is accelerating, only this
time the measurements involved “standard candles” called
Type-1a supernovae….

“It is still early days for the galaxy red-shift distortion technique,”
says ERIC LINDER AT THE UNIVERSITY OF CALIFORNIA AT
BERKELEY, who points out that a similar analysis of an earlier
cosmic epoch is currently being undertaken by the DEEP2
survey in the US. “But this work opens up a new window on
the mystery of dark energy, and right now we can use all the
views we can get!”

Zach January 31, 2008 at 0:08

I don’t know much about the in-depth details of physics but I love to read all the theories that come in. I’ve had my own theory on the origin of dark energy and possibly dark matter. So if someone could prove me wrong i’d much appreciate it as my explanation seems much too simple. Anyways, I was thinking about the origin and I began thinking about the big bang. If the big bang was powerful enough to create all this then might it be possible that it was powerful enough to send matter and/or energy faster than the speed of light? If so wouldn’t that have propelled it into the future only to reappear later once it’s acceleration had slowed down below the speed of light? If that would even work out time wise, I don’t know. I don’t have the mathematical knowledge to apply this theory. Like I said before physics is just a hobby I enjoy reading about, I don’t have the time to learn the nitty gritty of it all but I thought I’d just pose this theory/question. Thanks.

Edg Duveyoung January 31, 2008 at 11:28

http://tinyurl.com/3cxdhu

On the above Web page, there is an in depth discussion of a theory by Kent Robertson that Kent first introduced to the world in a comic book format — way way back in the dark ages, 1959. I read it, and I don’t have the math to dispute it, but, hey, a veritable hoard of credentialed REAL SCIENTISTS have been as or more stymied trying to dismiss this theory by definitively showing it to be illogical or at odds with experimental facts.

Quote: “In 1967, Dr. Richard Feynman, Prof Emeritus of Cal Tech (Nobel Prize Laureate), skipped three classes he taught at that time to talk with K.B. Robertson (AKA Kent Robertson ben Abraham), one on one in his (Feynman’s) study, about the unprecedented statement ‘gravity is the 4th dimension’, after which time Dr. R. Feynman candidly conceded, ‘I am unable to disqualify it’.”

I propose that Kent’s theory offers new conceptual “footing” for the dark energy discussions. I hesitate to present this guy — he’s a genuine old school kook who never got the PhD to wave in front of establishment faces and was marginalized by the entrenched ivory tower of physics. Yeah, Kent is, gotta say it, “crazy,” but so was Mendel, eh? — oh it’s an old story to Thomas Kuhn. Cavendish could not stand the presence of a woman — koo koo nuts about them — but he weighed the Earth — go figure — whackoness doesn’t always trump genius!

I invite the minds here to give more than a mere scan to the above Web page and to try to overlook the personality of Kent, and imagine that someone as august as Hawking was offering this theory. Come on, for ten minutes, pretend this, and see if dark energy doesn’t become, GAWD I know what this sounds like, simple to understand.

A goodly amount of the folks here are legitimate authentic educated thinkers, and I will read your replies with a serious intent — I’d love to put this theory out of my mind for good, cuz it bugs me again and again without closure or advancement.

Help!

Edg

ljk January 31, 2008 at 12:13

Gamma ray fluxes from a cosmological dark matter simulation

Authors: E. Athanassoula, F.-S. Ling, E. Nezri, R. Teyssier

(Submitted on 30 Jan 2008)

Abstract: In this paper, we estimate the gamma-ray fluxes coming from dark matter annihilation in a complex Milky Way framework provided by a recent N-BODY HORIZON simulation. We first study the characteristics of the simulation and highlight the mass distribution within the galactic halo. The general dark matter density has a typical $r^{-3}$ power law for high radii but the inner behaviour is poorly constrained below the resolution of the simulation ($\sim 200$ pc). We identify clumps and subclumps and analyze their distribution as well as their internal structure. Inside the clumps, the power law is quite universal, $r^{-2.5}$ in the outer part with again strong uncertainties for smaller radii especially for light clumps. We show a full skymap of the astrophysical contribution to the gamma-ray fluxes in this N-BODY framework. Thanks to quite model independent and general assumptions for the high energy physics part, we evaluate the possible absolute fluxes and show some benchmark regions for the GLAST experiment. While individual clumps seem to be beyond detection reach, the galactic center region is promising and GLAST could be sensitive to the geometry and the structure of its dark matter distribution. We also point out that the lack of resolution leaves the inner structure of subhalos poorly constrained. Using the same clump spectrum and mass fraction, a clump luminosity boost of order ten can be achieved with a steeper profile in the inner part of the sub-halos.

Comments: 14 pages, 10 figures

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0801.4673v1 [astro-ph]

Submission history

From: Nezri [view email]

[v1] Wed, 30 Jan 2008 14:32:23 GMT (2137kb)

http://arxiv.org/abs/0801.4673

Administrator January 31, 2008 at 14:58

Zach, here’s one way to look at the question. According to everything we currently know, matter cannot move faster than the speed of light. However, built into modern cosmology is the idea of inflation, where spacetime itself expands faster than the speed of light (way, way faster!), and this does not violate anything Einstein said because he placed no limits on the expansion of spacetime. So we could imagine matter that was effectively out of view to us because its light had not had time to get to us.

But suppose somehow the Big Bang event did push matter into the future through mechanisms unknown and it then became visible to us. Ingenious and interesting idea, by the way! But I don’t think such matter could account for the dark matter now thought to be so influential in the cosmos because dark matter evidently played quite a role in the development of the galaxies we observe today. In other words, whatever accounts for the shape of galaxies has been there all along to take part in their ultimate formation, so a scenario where the stuff appeared from the future would have to explain what happened in the time since the Big Bang.

I can say all that but still have to add this huge qualifier: Nobody knows for a fact what either dark matter or dark energy are, and it may well be that the answer is just as remarkable as the solution you’ve proposed.

ljk February 2, 2008 at 8:02

Dark Fluid: Dark Matter And Dark Energy May Be
Two Faces Of Same Coin

(February 1, 2008) — Astronomers believe they can
“simplify the dark side of the universe” by shedding new
light on two of its mysterious constituents. Only 4% of the
universe is made of known material – the other 96% is
traditionally labeled into two sectors, dark matter and
dark energy.

“Both dark matter and dark energy could be two faces of
the same coin,” according to an astrophysicist. … > full story

http://www.sciencedaily.com/releases/2008/01/080131094056.htm

ljk February 2, 2008 at 9:58

Astronomers have used the VLT to measure the distribution
and motions of thousands of galaxies in the distant Universe.

This opens fascinating perspectives to better understand
what drives the acceleration of the cosmic expansion and
sheds new light on the mysterious dark energy that is
thought to permeate the Universe.

Read more and see the images and animations in ESO 04/08 at

http://www.eso.org/public/outreach/press-rel/pr-2008/pr-04-08.html

ljk February 4, 2008 at 12:27

Clustering Properties of Dynamical Dark Energy Models

Authors: P. P. Avelino, L.M.G. Beca, C.J.A.P. Martins

(Submitted on 1 Feb 2008)

Abstract: We provide a generic but physically clear discussion of the clustering properties of dark energy models. We explicitly show that in quintessence-type models the dark energy fluctuations, on scales smaller than the Hubble radius, are of the order of the perturbations to the Newtonian gravitational potential, hence necessarily small on cosmological scales. Moreover, comparable fluctuations are associated with different gauge choices.

We also demonstrate that the often used homogeneous approximation is unrealistic, and that the so-called dark energy mutation is a trivial artifact of an effective, single fluid description. Finally, we discuss the particular case where the dark energy fluid is coupled to dark matter.

Comments: 5 pages

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0802.0174v1 [astro-ph]

Submission history

From: Pedro Pina Avelino [view email]

[v1] Fri, 1 Feb 2008 17:36:39 GMT (10kb)

http://arxiv.org/abs/0802.0174

ljk February 7, 2008 at 11:45

Multi-wavelength signals of dark matter annihilations at the Galactic center

Authors: Marco Regis, Piero Ullio

(Submitted on 2 Feb 2008)

Abstract: We perform a systematic study of the multi-wavelength signal induced by weakly interacting massive particle (WIMP) annihilations at the Galactic Center (GC). Referring to a generic WIMP dark matter (DM) scenario and depending on astrophysical inputs, we discuss spectral and angular features and sketch correlations among signals in the different energy bands. None of the components which have been associated to the GC source Sgr A*, nor the diffuse emission components from the GC region, have spectral or angular features typical of a DM source. Still, data-sets at all energy bands, namely the radio, near infrared, X-ray and gamma-ray bands, contribute to place significant constraints on the WIMP parameter space. In general, the gamma-ray energy range is not the one with the largest signal to background ratio. In case of large magnetic fields close to the GC, X-ray data give the tightest bounds. The emission in the radio-band, which is less model dependent, is very constraining as well. The recent detection by HESS of a GC gamma-ray source, and of a diffuse gamma-ray component, limits the possibility of a DM discovery with the next generation of gamma-ray telescopes, like GLAST and CTA. We find that the most of the region in the parameter space accessible to these instruments is actually already excluded at other wave-lenghts. On the other hand, there may be still an open window to improve constraints with wide-field radio observations.

Comments: 25 pages, 32 figures

Subjects: High Energy Physics – Phenomenology (hep-ph); Astrophysics (astro-ph)

Cite as: arXiv:0802.0234v1 [hep-ph]

Submission history

From: Marco Regis [view email]

[v1] Sat, 2 Feb 2008 06:06:18 GMT (262kb)

http://arxiv.org/abs/0802.0234

ljk February 7, 2008 at 11:47

Dark energy: a quantum fossil from the inflationary Universe?

Authors: Joan Sola

(Submitted on 22 Oct 2007 (v1), last revised 6 Feb 2008 (this version, v2))

Abstract: The discovery of dark energy (DE) as the physical cause for the accelerated expansion of the Universe is the most remarkable experimental finding of modern cosmology. However, it leads to insurmountable theoretical difficulties from the point of view of fundamental physics. Inflation, on the other hand, constitutes another crucial ingredient, which seems necessary to solve other cosmological conundrums and provides the primeval quantum seeds for structure formation. One may wonder if there is any deep relationship between these two paradigms.

In this work, we suggest that the existence of the DE in the present Universe could be linked to the quantum field theoretical mechanism that may have triggered primordial inflation in the early Universe. This mechanism, based on quantum conformal symmetry, induces a logarithmic, asymptotically-free, running of the gravitational coupling. If this evolution persists in the present Universe, and if matter is conserved, the general covariance of Einstein’s equations demands the existence of dynamical DE in the form of a running cosmological term whose variation follows a power law of the redshift.

Comments: LaTeX, 14 pages, extended discussion. References added. Accepted in J. Phys. A: Mathematical and Theoretical

Subjects: High Energy Physics – Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Phenomenology (hep-ph)

Cite as: arXiv:0710.4151v2 [hep-th]

Submission history

From: Joan Sola [view email]

[v1] Mon, 22 Oct 2007 21:15:01 GMT (32kb)

[v2] Wed, 6 Feb 2008 19:54:00 GMT (33kb)

http://arxiv.org/abs/0710.4151

ljk February 7, 2008 at 13:44

Galaxy without dark matter puzzles astronomers

06:59 06 February 2008

NewScientist.com news service

Stephen Battersby

The spiral galaxy NGC 4736, which lies 15 million light years from Earth, does not need dark matter to explain the motion of its stars and gas, according to a new study (Image: David W Hogg/ Michael R Blanton/SDSS Collaboration)

What do you call an absence of darkness? Dark matter is supposed to be spread throughout the universe, but a new study reports a spiral galaxy that seems to be empty of the stuff, and astrophysicists cannot easily explain why.

In the outer regions of most galaxies, stars orbit around the centre so fast that they should fly away. The combined mass of all the observable inner stars and gas does not exert strong enough gravity to hold onto these speeding outliers, suggesting some mass is missing.

Most astronomers believe that the missing mass is made up of some exotic invisible substance, labelled dark matter, which forms vast spherical halos around each galaxy. Another possibility is that the force of gravity behaves in an unexpected way, a theory known as modified Newtonian dynamics, or MOND.

In the spiral galaxy NGC 4736, however, the rotation slows down as you move farther out from the crowded inner reaches of the galaxy. At first glance, that declining rotation curve is just what you would expect if there is no extended halo of dark matter, and no modification to gravity. As you move far away from the swarming stars of the inner galaxy, gravity becomes weaker, and so motions become more sedate.

The rotation measurements only stretch 35,000 light years out from the galactic centre, which is not far enough to confirm that first impression. So a team of astronomers in Poland developed a more sophisticated analysis.

Joanna Jalocha, Lukasz Bratek and Marek Kutschera of the Polish Academy of Science in Krakow have found a way to splice the rotation curve together with another measurement: the density of hydrogen gas far from the galactic centre.

According to their combined mathematical model, ordinary luminous stars and gas can indeed account for all the mass in NGC 4736.

Full article here:

http://space.newscientist.com/article/dn13280?DCMP=NLC-nletter&nsref=dn13280

ljk February 8, 2008 at 10:57

Strategies for Determining the Nature of Dark Matter

Authors: Dan Hooper, Edward A. Baltz

(Submitted on 5 Feb 2008)

Abstract: In this review, we discuss the role of the various experimental programs taking part in the broader effort to identify the particle nature of dark matter. In particular, we focus on electroweak scale dark matter particles and discuss a wide range of search strategies being carried out and developed to detect them. These efforts include direct detection experiments, which attempt to observe the elastic scattering of dark matter particles with nuclei, indirect detection experiments, which search for photons, antimatter and neutrinos produced as a result of dark matter annihilations, and collider searches for new TeV-scale physics.

Each of these techniques could potentially provide a different and complementary set of information related to the mass, interactions and distribution of dark matter. Ultimately, it is hoped that these many different tools will be used together to conclusively identify the particle or particles that constitute the dark matter of our universe.

Comments: 25 pages, 5 figures, Review intended for the Annual Review of Nuclear and Particle Science

Subjects: High Energy Physics – Phenomenology (hep-ph); Astrophysics (astro-ph)

Report number: FERMILAB-PUB-08-026-A

Cite as: arXiv:0802.0702v1 [hep-ph]

Submission history

From: Dan Hooper [view email]

[v1] Tue, 5 Feb 2008 21:27:40 GMT (134kb)

http://arxiv.org/abs/0802.0702

ljk February 19, 2008 at 10:44

The Dark UNiverse Explorer (DUNE): Proposal to ESA’s Cosmic Vision

Authors: Alexandre Refregier, the DUNE collaboration

(Submitted on 18 Feb 2008)

Abstract: The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter with unprecedented precision. For this purpose, DUNE is optimised for the measurement of weak gravitational lensing but will also provide complementary measurements of baryonic accoustic oscillations, cluster counts and the Integrated Sachs Wolfe effect. Immediate auxiliary goals concern the evolution of galaxies, to be studied with unequalled statistical power, the detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planets.

DUNE is an Medium-class mission which makes use of readily available components, heritage from other missions, and synergy with ground based facilities to minimise cost and risks. The payload consists of a 1.2m telescope with a combined visible/NIR field-of-view of 1 deg^2. DUNE will carry out an all-sky survey, ranging from 550 to 1600nm, in one visible and three NIR bands which will form a unique legacy for astronomy. DUNE will yield major advances in a broad range of fields in astrophysics including fundamental cosmology, galaxy evolution, and extrasolar planet search. DUNE was recently selected by ESA as one of the mission concepts to be studied in its Cosmic Vision programme.

Comments: submitted to Experimental Astronomy

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0802.2522v1 [astro-ph]

Submission history

From: Marian Douspis [view email]

[v1] Mon, 18 Feb 2008 17:39:24 GMT (626kb)

http://arxiv.org/abs/0802.2522

ljk February 19, 2008 at 11:29

Dark matter accretion wakes of high-redshift black holes

Authors: Roya Mohayaee, Jacques Colin

(Submitted on 18 Feb 2008)

Abstract: Anisotropic emission of gravitational waves during the merger or formation of black holes can lead to the ejection of these black holes from their host galaxies. A recoiled black hole which moves on an almost radial bound orbit outside the virial radius of its central galaxy, in the cold dark matter background, reaches its apapsis in a finite time. The low value of dark matter velocity dispersion at high redshifts and also the black hole velocity near the apapsis passage yield a high-density wake around these black holes. Gamma-ray emission can result from the enhancement of dark matter annihilation in these wakes. The diffuse high-energy gamma-ray background from the ensemble of such black holes in the Hubble volume is also evaluated.

Comments: Talk presented at “Jean-Pierre Lasota, X-ray binaries, accretion disks and compact stars” (October 2007); Abramowicz, M. Ed., New Astronomy Review, in press

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0802.2534v1 [astro-ph]

Submission history

From: Roya Mohayaee [view email]

[v1] Mon, 18 Feb 2008 20:11:39 GMT (336kb)

http://arxiv.org/abs/0802.2534

ljk February 20, 2008 at 0:45

First stars ‘may have been dark’

By Roland Pease

BBC Radio Science Unit

The “dark” stars may have been large and diffuse

The first stars to appear in the Universe may have been powered by dark matter, according to US scientists.

Normal stars are powered by nuclear fusion reactions, where hydrogen atoms meld to form heavier helium.

But when the Universe was still young, there would have been abundant dark matter, made of particles called Wimps: Weakly Interacting Massive Particles.

These would have fused together and obliterated each other long before nuclear fusion had the chance to start.

As a result, the first stars would have looked quite different from the ones we see today, and they may have changed the course of the Universe’s evolution – or at least held it up.

The theory, published in the journal Physical Review Letters, depends on particles that astronomers can’t see, but are certain exist, and physicists have never detected. But the indirect evidence for their existence is overwhelming.

Full article here:

http://news.bbc.co.uk/2/hi/science/nature/7252428.stm

ljk February 20, 2008 at 10:26

A new experiment at the US Department of Energy’s Fermi National Accelerator Laboratory announced this week that they’ve made some headway in this search. According to theories, when dark matter particles interact with regular matter, it’s different from the way regular matter interacts. The Fermilab experiment has ruled out one of the last possible ways that the theories have predicted this should happen.

Their experiment, called COUPP, uses a glass jar filled with a litre of iodotrifluoromethane (a fire-extinguishing liquid known as CF3I. As particles strike the CF3I, it causes tiny bubbles to form in the liquid. The scientists can detect these bubbles as they reach a millimetre in size. By watching the interactions, researchers should be able to know if they’re coming from regular matter or dark matter.

So far, their results contradict another search called the Dark Matter experiment (DAMA) in Italy, who claimed to see dark matter interactions. The results for the DAMA experiment predicted that COUPP should have found hundreds of dark matter interactions, but they didn’t see any.

This research appears in the February 15th issue of the journal Science.

Full article here:

http://www.universetoday.com/2008/02/19/bubble-experiment-fails-to-find-dark-matter/

ljk February 20, 2008 at 11:33

Evolution of a Kerr-Newman black hole in a dark energy universe

Authors: José A. Jiménez Madrid (1 and 2), Pedro F. González-Díaz (2) ((1) IAA, Granada (2)IMAFF, Madrid)

(Submitted on 3 Oct 2005 (v1), last revised 19 Feb 2008 (this version, v2))

Abstract: This paper deals with the study of the accretion of dark energy with equation of state $p=w\rho$ onto Kerr-Newman black holes. We have obtained that when $w greater than -1$ the mass and specific angular momentum increase, and that whereas the specific angular momentum increases up to a given plateau, the mass grows up unboundedly. On the regime where the dominant energy condition is violated our model predicts a steady decreasing of mass and angular momentum of black holes as phantom energy is being accreted.

Masses and and angular momenta of all black holes tend to zero when one approaches the big rip. The results that cosmic censorship is violated and that the black hole size increases beyond the universe size itself are discussed in terms of considering the used models as approximations to a more general descriptions where the metric is time-dependent.

Comments: 11 figures added. Some explanations extended. E-mails updated. References updated. Conclusions unchanged. Accepted in Gravitation & Cosmology

Subjects: Astrophysics (astro-ph)

Report number: IMAFF-RCA-05-09

Cite as: arXiv:astro-ph/0510051v2

Submission history

From: Jos\’e Antonio Jim\’enez Madrid [view email]

[v1] Mon, 3 Oct 2005 16:44:36 GMT (21kb)

[v2] Tue, 19 Feb 2008 12:26:59 GMT (69kb)

http://arxiv.org/abs/astro-ph/0510051

ljk March 31, 2008 at 21:56

South Pole telescope peers heavenward for dark energy

The giant instrument seeks clues that might identify the most powerful,
plentiful but elusive substance in the universe.

Los Angeles Times

http://www.latimes.com/news/nationworld/world/la-fg-spole30mar30,1,6401080,print.story

By William Mullen

March 29, 2008

AMUNDSEN-SCOTT STATION, ANTARCTICA — Anywhere on Earth
this would be a big telescope, as tall as a seven-story building, with
a main mirror measuring 32 1/2 feet across. But here at the South
Pole, it seems especially large, looming over a barren plain of ice
that gets colder than anywhere else on the planet.

Scientists built the instrument at the end of the world so they can
search for clues that might identify the most powerful, plentiful
but elusive substance in the universe: dark energy….

Swinging its massive mirror skyward, the South Pole Telescope
has begun to search the southern polar heavens for shreds of
evidence of the elusive stuff. Controlled remotely from the
University of Chicago, the $19.2-million telescope has quickly
succeeded in its first mission: finding unknown galaxy clusters,
clues to the emergence of dark energy.

The Chicago university has a stronger astronomy presence at
the pole than perhaps any other institution, having built several
smaller experimental telescopes there over the last 20 years.
This scope, however, was the most ambitious project by far….

Also out there, slinging two-by-fours alongside ironworkers
putting together the telescope’s main structure, was John E.
Carlstrom, a veteran South Pole astronomer and University of
Chicago astrophysicist who is heading up the international team
that designed and constructed the telescope.

SENIOR SCIENTISTS at six other institutions are collaborating
with Carlstrom’s Chicago team, including the University of Illinois
at Urbana-Champaign, UC BERKELEY, NASA’s Jet Propulsion
Laboratory, and Harvard, Case Western Reserve and McGill
universities. The project is funded mainly by the National
Science Foundation with additional money coming from two
California donors, the Kavli Foundation and the Gordon and
Betty Moore Foundation.

Comments on this entry are closed.