# @worldscifest on Instagram

- **Type:** Image
- **Original URL:** https://www.instagram.com/p/Ba4SNYelKzy
- **Gondola URL:** https://gondola.cc/posts/2460888-worldscifest-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/79530ac8b9.jpg
- **Posted:** 2017-10-30T16:49:05.000+00:00
- **Account Owner:** WorldScienceFestival (@WorldSciFest) — https://gondola.cc/WorldSciFest

## Caption

#MondayMotivation.
#Repost @nasahubble ・・・
Using #Hubble, astronomers have discovered that the brightest #galaxies within galaxy clusters “#wobble” relative to the cluster’s center of mass. This unexpected result is inconsistent with the current standard model of #darkmatter and may provide insights into the #nature of dark matter.
Dark matter constitutes just over 25 percent of all matter in the universe but cannot be directly observed. Invisible halos of dark matter enclose galaxies and galaxy clusters (massive groupings of up to a thousand galaxies). At the dense core of each galaxy cluster is a massive #galaxy called the “brightest cluster galaxy” (BCG). The standard model of dark matter predicts that once a galaxy cluster has returned to a “relaxed” state after experiencing the turbulence of a merging event, the BCG is held in place by the enormous gravitational influence of dark matter and does not move from the cluster’s center.
But after analyzing ten galaxy clusters observed with Hubble, #astronomers have found that their BCGs are not fixed at the center as expected.
The Hubble data indicate that they are “wobbling” around the center of mass of each cluster long after the galaxy cluster has returned to a relaxed state. In other words, the center of the visible parts of a galaxy cluster and the center of the total mass of the cluster — including its dark matter — are offset.
The wobbling of the BCGs could be analyzed because the galaxy clusters studied act as #gravitational lenses. Their mass warps spacetime, distorting light from more distant objects behind them. This effect was used to map the cluster’s dark matter, work out the position of the center of mass, and then measure the offset of the BCG from the center.
If this “wobbling” is the result of the behavior of dark matter, then it is inconsistent with the standard model of dark matter and can only be explained if dark matter particles can interact with each other — a contradiction to the current understanding of dark matter. This may indicate that new fundamental physics is required to solve the #mystery of dark matter.

Credit: NASA/ESA/Hubble
#NASA #Hubble #space #science #astronomy #universe

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## Tags

mondaymotivation, astronomy, wobble, nasa, hubble, darkmatter, astronomers, gravitational, space, galaxy, mystery, repost, nature, science, galaxies, universe

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