Wednesday, April 1, 2020

The Mystery of the Expansion of the Universe

From Phys.org:
The Earth, solar system, the entire Milky Way and the few thousand galaxies closest to us move in a vast "bubble" that is 250 million light years in diameter, where the average density of matter is half as high as for the rest of the universe. This is the hypothesis advanced by a theoretical physicist from the University of Geneva (UNIGE) to solve a conundrum that has been splitting the scientific community for a decade: At what speed is the universe expanding? Until now, at least two independent calculation methods have arrived at two values that are different by about 10% with a deviation that is statistically irreconcilable. This new approach, which is set out in the journal Physics Letters B, erases this divergence without making use of any "new physics." (Read more.)

From Live Science:
Nine hundred million years after the Big Bang, in the epoch of our universe's earliest galaxies, there was already a black hole 1 billion times the size of our sun. That black hole sucked in huge quantities of ionized gas, forming a galactic engine — known as a blazar — that blasted a superhot jet of bright matter into space. On Earth, we can still detect the light from that explosion more than 12 billion years later.
Astronomers had previously discovered evidence of primeval supermassive black holes in slightly younger "radio-loud active galactic nuclei," or RL AGNs. RL AGNs are galaxies with cores that look extra-bright to radio telescopes, which is considered evidence that they contain supermassive black holes. Blazars are a unique type of RL AGN that spit out two narrow jets of "relativistic" (near-light-speed) matter in opposite directions. Those jets emit narrow beams of light at many different wavelengths and have to be pointed right at Earth for us to detect them across such vast distances. This new blazar discovery moves the date of the oldest confirmed supermassive black hole to within the first billion years of the universe's history and suggests there were other, similar black holes in that era that we haven't detected. (Read more.)
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