Senior Review and rankings for the ten missions under evaluation for NASA Astrophysics in 2008 have been published.
Bottom line here is that NASA funds are too tight, so some operating missions are being reviewed for descoping or shut down.
The new test of general relativity concerns a distant galactic core or quasar called OJ287, which is known to emit a pair of bright optical bursts every 12 years or so. In 1988, Valtonen and others suggested that this emission is powered by a primary black hole 18 billion times more massive than the Sun, around which orbits a second black hole some 200 times lighter. In such a binary system, the lighter object passes through matter in the accretion disk of the primary black hole twice per orbit, releasing a burst of energy each time it does so.
By modelling such a system, researchers could then put general relativity to the test by predicting when the next burst should occur. At the time, the next major bursts (which were due in the mid 1990s) could only be predicted with an accuracy of a few weeks, which was too vague to test general relativistic effects. But early last year, based on refined models and years spent monitoring OJ287, Valtonen and others were able to predict the date on which the next bright pulse should appear: 13 September 2007, give or take a day or two.
To have any hope of detecting the pulse, more than 25 astronomers from 10 countries had to work together. This is because in September OJ287 rises in the east just before sunrise, and is therefore only visible at any one location on Earth for about 30 minutes before the sky becomes too bright. By starting observations in Japan, followed by China, Europe and ending in the Canary Islands, observers were able to follow the sunrise westward around the globe and maximise observing time. In total, about 100 measurements were made between 4 September and 20 October, some of which by amateur astronomers.
This "grand challenge" project features the largest N body simulation ever performed: we have simulated the 13.7 Gyr long evolution of 4096^3 dark matter particles in a 2 Gpc/h periodic box, running the RAMSES code for a couple of month on the 6144 processors of the new BULL supercomputer of the CEA supercomputing center (Centre de Calcul Recherche et Technologie).
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For the first time, we have performed a simulation of half the observable universe, with enough resolution to describe a Milky Way-like galaxy with more than 100 dark matter particles.
The video is pretty nifty.
