Galaxy clusters are the largest collapsed objects in the Universe and are ideal for studying the properties of dark energy, the mysterious form of repulsive gravity that is driving the accelerated expansion of the Universe. The growth of these structures was initially driven only by the attractive force of gravity, but then later there was competition with the repulsive force of dark energy.
Understanding the nature of dark energy is one of the biggest problems in science. Possibilities include the cosmological constant, equivalent to the energy of empty space, a modification in general relativity on the largest scales, or a more general physical field. The results are remarkably consistent with those from previous results that measure the expansion of the Universe using distance measurements, revealing that general relativity works as expected on large scales.
And Today
Herschel Mission Finds Galactic Growth Slow and Steady
The Herschel Infrared Space Observatory discovered that galaxies do not always need to collide with each other to drive vigorous star birth. The finding overturns a long-held assumption and paints a more stately picture of how galaxies evolve. The new results are based on Herschel's observations of two patches of sky, each about one-third the size of the full moon.
These observations are unique because Herschel can obtain data at a wide range of infrared light and reveal a more complete picture of star birth than ever seen before.
Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA JPL, which contributed mission-enabling technology for two of Herschel's three science instruments.
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