FEATURED IMAGE: 17 Oct 2019, 18:04 UTC | The Clumpy and Lumpy Death of a Star 20 October 2019, 1:00:15UTC RSS RSS | About | Contact | Site Map
Home » News & Blogs » Dark Matter Riches? Why Some Galaxies Have More Than Others (Synopsis)
Bookmark and Share
Starts With A Bang!

Dark Matter Riches? Why Some Galaxies Have More Than Others (Synopsis)

29 Aug 2016, 14:01 UTC
Dark Matter Riches? Why Some Galaxies Have More Than Others (Synopsis)
(200 words excerpt, click title or image to see full post)

“Motions of the stars tell you how much matter there is. They don’t care what form the matter is, they just tell you that it’s there.” -Pieter van Dokkum
Everything in the Universe was born with the same ratios of dark matter to normal matter: approximately 5-to-1. It shows up in everything from the cosmic microwave background to galaxy clustering to internal motions of spiral and elliptical galaxies, including the Milky Way.
From simulations and inferred maps, dark matter (blue) may form some clumps, but overall exists in a massive, diffuse halo around the luminous, disk-like part of galaxies we’re familiar with. Image credit: NASA, ESA, and T. Brown and J. Tumlinson (STScI).
But some galaxies, particularly dwarf galaxies and rapidly moving galaxies within clusters, show a significant enhancement of dark matter over what’s expected. Ratios of even hundreds-to-1 aren’t unheard of. This is a difficulty for theorists to explain, but it doesn’t mean that dark matter is wrong.
Dwarf galaxies, like the one imaged here, have a much greater than 5-to-1 dark matter to normal matter ratio, as bursts of star formation have expelled much of the normal matter. Image credit: ESO / Digitized Sky Survey 2.
On the ...

Latest Vodcast

Latest Podcast

Advertise PTTU

NASA Picture of the Day

Astronomy Picture of the Day

astronomy_pod