08-10-11

Does dark energy accelerate space missions ? ESA has a plan to launch Euclid mission to find more about dark energy.

 

 

October 05, 2011

 

dark energy, ESA, cosmology,

The movie stills pictured above illustrate the formation of clusters and large-scale filaments in the Cold Dark Matter model with dark energy.

 

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http://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/...

 

wikimedia commons

 

Perfect timing: Yesterday, three astronomers received the news every scientist wants: they would be receiving the physics Nobel Prize for their work in discovering dark energy, a repulsive force that is ramping up the expansion of the universe.

 

So it was somehow fitting that, on the very same day, European Space Agency officials were approving a space mission, called Euclid, that would pin down more precisely dark energy’s key parameters.

 

“It was just coincidence, really,” says David Schlegel, principal investigator for BOSS, a ground-based mission that is also trying to get a handle on the stuff that looks a lot like a cosmological constant, the fudge factor that Einstein introduced in his relativity equations when he thought the universe was static, but later regretted.

 

Okay, so the prize has nothing to do with ESA’s decision.

 

But will it bolster the case for other dark energy missions?

 

In the United States, NASA, the Energy Department and the National Science Foundation are all trying to get a piece of the action. NASA’s WFIRST is the most expensive mission and the most sought after (it was ranked tops in the US decadal survey), and it’s probably the most capable.

 

 

But it’s stuck in line behind the James Webb Space Telescope, and so most observers think it doesn’t have a chance of flying at all until the 2020s.

 

The selection of Euclid, a very similar mission that would scoop much of the early science, may put further pressure on NASA to attempt what has failed in the past: a mission merger.

 

 

Ground-based dark energy experiments may get a lot more bang for the buck -- but even there, money is a problem.

 

 

LSST, another community favorite that will make major strides in measuring dark energy, still needs cash.

 

 

In a universe that keeps moving faster and faster, missions like LSST and WFIRST seem to get farther and farther away.

 

“It seems like it’s so far in the future,” says Schlegel.

 

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http://blogs.nature.com/news/2011/10/post_85.htm

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28-08-08

XMM-Newton’s massive discovery - 25 August 2008

ESA’s orbiting X-ray observatory XMM-Newton has discovered the most massive cluster of galaxies seen in the distant Universe until now. The galaxy cluster is so big that there can only be a handful of them at that distance, making this a rare catch indeed. The discovery confirms the existence of dark energy.The newly-discovered monster, known only by the catalogue number 2XMM J083026+524133, is estimated to contain as much mass as a thousand large galaxies. Much of it is in the form of 100-million-degree hot gas. It was first observed by chance as XMM-Newton was studying another celestial object and 2XMM J083026+524133 was placed in a catalogue for a future follow-up. Georg Lamer, Astrophysikalisches Institut Potsdam, Germany, and a team of astronomers discovered the record-breaking cluster as they were performing a systematic analysis of the catalogue. Based on 3500 observations performed with XMM-Newton's European Photon Imaging Camera (EPIC) covering about 1% of the entire sky, the catalogue contains more than 190 000 individual X-ray sources. The team were looking for extended patches of X-rays that could either be nearby galaxies or distant clusters of galaxies. J083026+524133 stood out because it was so bright. While checking visual images from the Sloan Digital Sky Survey, the team could not find any obvious nearby galaxy in that location. So they turned to the Large Binocular Telescope in Arizona and took a deep exposure.Sure enough, they found a cluster of galaxies. So the team calculated a distance of 7.7 thousand million light-years and the cluster's mass using the XMM-Newton data. This was not a surprise because XMM-Newton is sensitive enough to routinely find galaxy clusters at this distance. The surprise was that the cluster contains a thousand times the mass of our own galaxy, the Milky Way.2XMM J083026+524133“Such massive galaxy clusters are thought to be rare objects in the distant Universe. They can be used to test cosmological theories,” says Lamer. Indeed, the very presence of this cluster confirms the existence of a mysterious component of the Universe called dark energy. No one knows what dark energy is, but it is causing the expansion of the Universe to accelerate. This hampers the growth of massive galaxy clusters in more recent times, indicating that they must have formed earlier in the Universe. “The existence of the cluster can only be explained with dark energy,” says Lamer. Yet he does not expect to find more of them in the XMM-Newton catalogue. “According to the current cosmological theories, we should only expect to find this one cluster in the 1% of sky that we have searched,” says Lamer. In other words, the team have found a cosmic ‘needle in a haystack’.Notes for editors:‘2XMM J083026+524133: The most X-ray luminous cluster at redshift 1’ by G. Lamer, M. Hoeft, J. Kohnert, A. Schwope, and J. Storm will be published in a forthcoming issue of the journal Astronomy & Astrophysics. The XMM-Newton science teams are based in several European and US institutes, grouped into three instrument teams and the XMM-Newton Survey Science Centre (SSC). Science operations are managed at ESA’s European Space Astronomy Centre (ESAC), at Villanueva de la Cañada near Madrid, Spain. Spacecraft operations are managed at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.Copyright : ESA PORTAL http://www.esa.int/esaCP/SEMY70XIPIF_index_0.htmlXMM NEWTON

19-01-08

Zoeken naar het eerste licht in het universum met de Planck Ruimtetelescoop

De ESA wil in 2008 met een Ariane 5 raket de Herschell telescoop tegelijkertijd met de Planck satelliet lanceren. Planck is een kosmologische missie, ontworpen om de Big Bang Theorie over de oorsprong van het heelal te onderzoeken. Net als WMAP zal Planck de Kosmische Achtergrondstraling bekijken. Planck moet de geometrie, de dichtheid en de snelheid waarmee het heelal uitdijt bepalen. De resultaten zouden met een factor 10 beter moeten zijn dan WMAP. Aan boord heeft Planck twee instrumenten die een brede band van frequenties tussen 30 en 857 Gigahertz kunnen bestuderen.Planck

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12-01-08

Sterrenstelsels die ontstaan zijn een miljard jaar na de Big Bang

Deze foto toont het "Hubble Ultra Deep Field".Verschillende stipjes op deze foto zijn lichtzwakke,compacte sterrenstelsels die behoren tot de verst waargenomenobjecten tot op heden. Ze blijken ontstaante zijn een miljard jaar na de Big Bang. Deze sterrenstelsels met miljoenen sterren zijn honderd tot duizend maal kleiner dan ons Melkwegstelsel. Sommige van deze sterrenstelsels lijken versmolten metelkaar te zijn wat erop wijst dat ze grotere structuren (clusters) aan het vormen zijn. Deze opname dateert van september 2007. Het waarnemen van deze data gebeurde door de Hubble ruimtetelescoop en Nasa's infrarood ruimtetelescoop Spitzer.Blauw licht toont de aanwezigheid van jonge sterren. Het afwezig zijn van infrarood licht gezien door Spitzer toont aan dat hethier om echt jonge sterrenstelsels gaat die geen vorige generatie vanoudere sterren bezitten.copyright Hubble Space Telescope NewscenterHubble