sdss – Shamskm: A site to exchange knowledge and solutions

BOSS Quasars Unveil a New Era in the Expansion History of the Universe

By Guest PostNovember 21, 2012Scienceacceleration, analytic techniques, ancient universe, andreu font ribera, apache point observatory, bao, baryon, baryon acoustic oscillations, berkeley lab, bigboss, bill carithers, BOSS, clouds, cosmology, dark energy, dark matter, data sets, david schlegel, deceleration, density variation, digital sky survey, early universe, evolution, expanse of sky, expansion, gas clouds, gas density, gravity, hydrogen absorption lines, intergalactic gas, lyman alpha forest, mocks, new mexico, nicholas ross, oscillation, patrick mcdonald, quasars, riemann linux cluster, sdss, sloan, Space, spectra, spectroscopic, survey, universe, volume

Berkeley Lab scientists and their Sloan Digital Sky Survey colleagues use quasars to probe dark energy over 10 billion years in the past

BOSS, the Baryon Oscillation Spectroscopic Survey, is mapping a huge volume of space to measure the role of dark energy in the evolution of the universe. BOSS is the largest program of the third Sloan Digital Sky Survey (SDSS-III) and has just announced the first major result of a new mapping technique, based on the spectra of over 48,000 quasars with redshifts up to 3.5, meaning that light left these active galaxies up to 11.5 billion years in the past.

“No technique for dark energy research has been able to probe this ancient era before, a time when matter was still dense enough for gravity to slow the expansion of the universe, and the influence of dark energy hadn’t yet been felt,” says BOSS principal investigator David Schlegel, an astrophysicist in the Physics Division of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). “In our own time, expansion is accelerating because the universe is dominated by dark energy. How dark energy effected the transition from deceleration to acceleration is one of the most challenging questions in cosmology.” (more…)

Clocking an Accelerating Universe: First Results from BOSS

By Guest PostApril 4, 2012Scienceaccelerate, adam riess, apache point observatory, bao, baryon acoustic oscillation, berkeley lab, beth reid, big bang, brian schmidt, cmb, cosmic microwave background, dan long, dark energy, david schlegel, density peak, einstein, eric huff, euclidean universe, Galaxy, george smoot, gravitational attraction, gravity, high z supernova, hubble, martin white, megaparsecs, Milky Way, new mexico, nobel prize, phenomenon, redshifts, saul perlmutter, scp, sdss, sloan telescope, spectrograph, statistical analysis, universe, zosia rostomian

Berkeley Lab scientists are the leaders of BOSS, the Baryon Oscillation Spectroscopic Survey. They and their colleagues in the third Sloan Digital Sky Survey have announced the most precise measurements ever made of the era when dark energy turned on.

Some six billion light years distant, almost halfway from now back to the big bang, the universe was undergoing an elemental change. Held back until then by the mutual gravitational attraction of all the matter it contained, the universe had been expanding ever more slowly. Then, as matter spread out and its density decreased, dark energy took over and expansion began to accelerate.

Today BOSS, the Baryon Oscillation Spectroscopic Survey, the largest component of the third Sloan Digital Sky Survey (SDSS-III), announced the most accurate measurement yet of the distance scale of the universe during the era when dark energy turned on. (more…)

Astrophysicists Find Evidence of Black Holes Ripping Stars Apart

By Guest PostOctober 17, 2011Scienceaccretion disk, active galactic nuclei, astrophysicists, black holes, chaotic orbits, cosmologists, dennis zaritsky, destroying stars, evidence of black holes, intermediate mass, johns hopkins university's, large galaxies, sdss, sloan digital sky survey, steward observatory, super-massive black hole, suvi gezari, university of arizona

*Sifting through observation data obtained of more than 2 million galaxies, a research team including UA astronomer Dennis Zaritsky has discovered phenomena telling of stars dying a violent death.

Astrophysicists at the University of Arizona and elsewhere have found evidence of black holes destroying stars, a long-sought phenomenon that provides a new window into general relativity.

The research, reported in the latest issue of the Astrophysical Journal, also opens up a method to search for the possible existence of a large population of presently undetectable “intermediate mass” black holes, which are hypothesized to be precursors to the super-massive black holes at the centers of most large galaxies. (more…)

Just Four Percent of Galaxies Have Neighbors Like the Milky Way

By Guest PostMay 26, 2011Scienceanalyses of data, big bang, cdm, cold dark matter theory, computer model, formation of our galaxy, Galaxy, luminosity, magellanic clouds, Milky Way, nigel sharp, optical sky, risa wechsler, sdss, stanford university, universe

*Our home galaxy belongs to a rare subset among the billions that populate the cosmos*

How unique is the Milky Way?

To find out, a group of researchers led by Stanford University astrophysicist Risa Wechsler compared the Milky Way to similar galaxies and found that just four percent are like the galaxy Earth calls home. (more…)

Measuring the Distant Universe in 3-D

By Guest PostMay 7, 2011Science3 d map, absorption, anže slosar, apache point observatory, bao, baryon acoustic oscillation, baryon oscillation, baryon oscillation spectroscopic survey, berkeley lab, bill carithers, BOSS, centers of galaxies, dark energy, david schlegel, james rich, lyman alpha forest, map intergalactic hydrogen gas, new mexico, of light years, precision tool, quasars, red galaxies, redshift, sdss, sloan digital sky survey, sloan telescope, spectrum, supermassive black holes, universe, wiggly structure

*Berkeley Lab-led BOSS proves it can do the job with quasars*

The biggest 3-D map of the distant universe ever made, using light from 14,000 quasars — supermassive black holes at the centers of galaxies many billions of light years away — has been constructed by scientists with the third Sloan Digital Sky Survey (SDSS-III).

The map is the first major result from the Baryon Oscillation Spectroscopic Survey (BOSS), SDSS-III’s largest survey, whose principal investigator is David Schlegel of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). The huge new map was presented at the April meeting of the American Physical Society in Anaheim, CA, by Anže Slosar of Brookhaven National Laboratory. (more…)

Tag Archives: sdss