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Astronomers Release the Largest Color Image of the Sky Ever Made

The largest image of the sky yet made – more than a trillion pixels – has been released by the multi-institutional third Sloan Digital Sky Survey (SDSS-III) at a press conference at the American Astronomical Society meeting in Seattle. The largest component of SDSS-III is the Baryon Oscillation Spectroscopic Survey, BOSS, led by Berkeley Lab scientists, now engaged in producing an even larger map of the sky.

Searching for Dark Energy with the Whole World’s Supernova Dataset

The Supernova Cosmology Project’s Union2 compilation and reanalysis of decades of the world’s best supernova surveys, with the addition of six high-redshift supernovae, puts new bounds on possible values for the nature of dark energy. Einstein’s cosmological constant comfortably fits the data, but there’s still plenty of room at the top for dynamical theories.

Measuring a Monstrous Supernova

Members of the Nearby Supernova Factory based at Berkeley Lab discovered and analyzed a rare Type Ia supernova whose progenitor star had a mass some two and a half times that of our sun – much more mass than a Type Ia progenitor should be able to accumulate before it explodes. The data they gathered is the most complete ever for such an unusual beast; only one model really fits, the merger of two white dwarf stars.

Foiling an Attack on General Relativity

In an attempt to explain away invisible dark matter and dark energy, some theorists have offered new theories of gravity that try to improve on Einstein’s General Theory of Relativity. A new study inspired by the work of a Berkeley Lab cosmologist indicates that at least one of these new theories is wrong.

Weak Lensing Gains Strength

Berkeley Lab cosmologists were part of an international team that has extended the relationship between the x-ray luminosity and the mass of galaxy clusters as measured by gravitational lensing, improving the reliability of mass measurements of much older, more distant, and smaller galactic structures. These refined measurements will benefit both the understanding of dark matter and the nature of dark energy as well.

The Evolving Search for the Nature of Dark Energy

Three-quarters of the Universe is dark energy, but nobody knows what it is. Is it an unknown form of energy that fills space, or an illusion caused by extra dimensions of space? Or is it just a flaw in Einstein’s theory of gravity? Proven techniques for investigating these questions are being refined, while new techniques are beginning to be applied to one of the most pressing problems in 21st-century physics. Part 1 discusses supernovae as standard candles.

The Evolving Search for the Nature of Dark Energy

Baryon acoustic oscillations provides a “standard ruler” for the Universe, a way to measure the details of dark energy.

The Evolving Search for the Nature of Dark Energy

Gravitational lensing, which depends on Einstein’s Theory of General Relativity, directly tests its ability to predict the growth of large-scale structure.

First Light for BOSS – A New Kind of Search for Dark Energy

BOSS, the Baryon Oscillation Spectroscopic Survey, is the most ambitious attempt yet to map the expansion history of the Universe using the technique known as baryon acoustic oscillation. BOSS achieved first light on September 14 with an upgraded spectrographic system on the 2.5-meter telescope at Apache Point Observatory.

Cosmology’s Best Standard Candles Get Even Better

The Nearby Supernova Factory has discovered an efficient method for standardizing the intrinsic brightness and thus the distance to the cosmic milestones known as Type Ia supernovae. The discovery underlines the crucial importance of spectroscopy in the quest to understand dark energy.