#cosmology

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Unlike other planets, auroras on Uranus are not in line with the poles. This is because Uranus' magnetic field is tilted by nearly 60 degrees. The reason is unknown, but one theory is that it was caused by whatever event made Uranus spin on its side compared to its orbital axis.

via The Downlink Newsletter, December 22, 2023, The Planetary Society

Seeing the Web Connecting Galaxies Across the Universe

Look deeply into the Universe; the bright galaxies are the first thing you'll see. Surrounding and connecting these islands of stars is the cosmic web. These are streams of gas that flow into galaxies, supporting their star formation. Astronomers have used the new Keck Cosmic Web Imager in Hawaii to image the cosmic web, revealing the filamentary network that connects galaxies across billions of light-years of space. Previously, the web was only visible when illuminated by bright objects like nearby quasars, but this new technique can show even the faintest material.

https://www.universetoday.com/163425/seeing-the-web-connecting-galaxies-across-the-universe/

New research has imaged the Cosmic Web of cold dark gas that interconnects the Universe's galaxies. Image Credit: Martin et al. 2023.

Colliding Neutron Stars Could Help Measure the Expansion of the Universe

Every time neutron stars collide, astronomers get another opportunity to measure the expansion rate of the Universe. Recent studies have shown that these collisions, kilonovae, are remarkably spherical and could be described by a single temperature, serving as standard candles for measuring cosmological distance. An analysis of the 2017 kilonova explosion found that its distance supports existing measurements for the Universe's expansion rate and could help relieve the "Hubble tension."

https://nbi.ku.dk/english/news/news23/colliding-neutron-stars-provide-a-new-way-to-measure-the-expansion-of-the-universe/

Two ways of measuring the expansion of the Universe

Finally! Astronomers are Starting to See the First Galaxies Coming Together with JWST

Although we've seen lots of news about the most distant galaxies discovered with JWST, astronomers are finally starting to collect enough data to build a deeper understanding of the early Universe. The ratio between galaxies and their heavy elements held constant in the local Universe through the last 12 billion years of history. But the youngest galaxies look different. They don't have that same ratio of stars to heavier elements because they haven't gone through the cycles of star formation and star death yet, enriching gas clouds with metals.

https://www.eurekalert.org/news-releases/1002438

The big galaxy in the foreground is named LEDA 2046648, and is seen just over a billion years back in time, while most of the others lie even farther away, and hence are seen even further back in time. ESA/Webb, NASA & CSA, A. Martel.

The Case for a Small Universe

Astronomers don't know if the Universe is finite or infinite. Whatever the case, it's larger than the Observable Universe, which measures 93 billion light-years across. A new paper proposes that the actual Universe is comparatively tiny, not much bigger than its observed size - just a few orders of magnitude larger. A smaller Universe solves some problems with other theories of cosmology, including inflation and the amount of dark energy in the Universe.

http://arxiv.org/abs/2309.03272

Large scale structure of the Universe

Researchers have found a new way to measure dark – the mysterious force that makes up more than two-thirds of the and is responsible for its accelerating expansion – in our own backyard.

is the only that isn’t running away from us, so by studying its mass and movement, we may be able to make some determinations about dark energy.


https://www.cam.ac.uk/research/news/dark-energy-could-be-measured-by-studying-the-galaxy-next-door

Paper by Benisty et al. (2023):
https://iopscience.iop.org/article/10.3847/2041-8213/ace90b