Scientists Detect Subtle Cosmic Motion
Oh hey, now this is neat. Complex, but neat. A team led by astronomer Alexander Kashlinsky at NASA’s Goddard Space Flight Center, is looking out at distant clusters of galaxies have been tracking the motions of those clusters as they move through space. And, they’ve found something unexpected, something they are calling “dark flow.” Essentially, the motions of those clusters have a little “outward tug” that seems to imply a gravitational attraction by something (matter) that lies beyond the cosmic horizon. This tug is independent of the clusters’ own motions and it can’t be accounted for by the expansion of space.
How did astronomers find this dark flow? They used the Wilkinson Microwave Anisotropy Probe (WMAP) to measure the photons of microwave light as they pass by and are scattered by hot x-ray-emitting gases in the clusters. Essentially, the astronomers dug into the spectra of the scattered light to look for a very tiny shift in the microwave background’s temperature in the direction of the clusters. They looked at a large number of clusters using the technique and found this motion that seems to affect clusters up to 6 billion light-years away. When they measured the motion, they clocked it at nearly 3.2 million kilometers per hour and its direction of flow points directly at a 20-degree-wide patch of sky between the constellations Centaurus and Vela.
What does this mean? You can read more about the finding in a Goddard press release. Essentially, however, astronomers are still refining the measurements, but it seems safe to say that it means stuff is moving faster at greater distances than they expected. And, it’s directional, which is challenging to explain unless you invoke some kind of gravitational influence of unseen matter in the attracting region. What’s there? Good question. Stay tuned!
