The dark side of the diffuse galaxies

The dark side of the fluffiest galaxies
A region of the Virgo cluster of galaxies containing the ultra-diffuse galaxy VCC 1287. The main image is 500 thousand light years across, uses a negative image for contrast, and was obtained with a 10-centimetre diameter amateur telescope in Switzerland (Antares Observatory). The zoom-in colour-composite image of VCC 1287 is from the 4-metre Canada-France- Hawai'i telescope. The coloured symbols show globular star clusters targeted for orbital speed measurements with the 10-metre Gran Telescopio CANARIAS (GTC). Credit: IAC

A team of International astronomers, led by members of the Instituto de Astrofísica de Canarias, has measured for the first time the mass of an ultra-diffuse galaxy using the Gran Telescopio CANARIAS (GTC).

Galaxies, in all forms including spirals, ellipticals, giants and dwarfs, have been widely studied over the past century. To the surprise of the scientific community last year, a new type of galaxy was discovered, residing in a galactic megalopolis known as the Coma Cluster, some 300 million light years away from Earth. Even though they are very numerous, these ultradiffuse have gone unnoticed until now because they are very faint. Their stars are spread over a very large area, which makes it particularly difficult to distinguish them from the sky background.

"These galaxies are particularly interesting, given that the violent environment in which they are situated would have destroyed them long ago, were they not protected by a large amount of dark matter," says Michael Beasley, the first author or the article published in the journal Astrophysical Journal Letters. "To test this fascinating idea was possible after identifying an ultradiffuse galaxy near enough to study in detail."

This galaxy, VCC 1287, is situated in the Virgo Cluster, some 50 million light years away, and it is surrounded by a swarm of globula clusters, which are key to studying its dark matter content. "Globular clusters, made up of hundreds of thousands of stars, orbit within the gravitational field of the ultradiffuse galaxy," says Aaron Romanowsky of San José State University (U.S.) one of the authors of the article. "The heavier the galaxy, the more rapidly its globular clusters move, so they can be used as a cosmic balance."

Using the Gran Telescopio CANARIAS (GTC) the team found that these move at high velocity, pulled by a surprisingly strong . "Even though dark matter is present in other galaxies, this is an exceptional case," concludes Beasley. "For each kilogramme of ordinary material, VCC 1287 contains 3 tonnes of dark matter. So we can say that ultradiffuse galaxies are essentially composed of , with very few stars." The scientists say this conclusion poses another question: "How is it possible for galaxies so diffuse and dark to exist?"


Explore further

Hubble sees a swarm of ancient star clusters around a galaxy

More information: Michael A. Beasley et al, AN OVERMASSIVE DARK HALO AROUND AN ULTRA-DIFFUSE GALAXY IN THE VIRGO CLUSTER, The Astrophysical Journal (2016). DOI: 10.3847/2041-8205/819/2/L20
Provided by Instituto de Astrofísica de Canarias (IAC)
Citation: The dark side of the diffuse galaxies (2016, May 24) retrieved 16 June 2019 from https://phys.org/news/2016-05-dark-side-diffuse-galaxies.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
39 shares

Feedback to editors

User comments

May 24, 2016
Dark matter is displaced by matter.

Dark matter fills 'empty' space. Dark matter strongly interacts with matter. Dark matter is displaced by matter.

[0903.3802] The Milky Way's dark matter halo appears to be lopsided

"the emerging picture of the dark matter halo of the Milky Way is dominantly lopsided in nature."

The Milky Way's halo is not a clump of dark matter traveling along with the Milky Way. The Milky Way's halo is lopsided due to the matter in the Milky Way moving through and displacing the dark matter, analogous to a submarine moving through and displacing the water.

What ripples when black holes collide is what waves in a double slit experiment, the strongly interacting dark matter which fills 'empty' space.

Einstein's gravitational wave is de Broglie's wave of wave-particle duality, both are waves in the strongly interacting dark matter.

Dark matter displaced by matter relates general relativity and quantum mechanics.

May 24, 2016
These diffused galaxies,probably are old and ran out of inner core feed material for their CCM , where it cooled off and its orbiting electron magnetic field has inducted alot of the CCM's mass back into neutrons so it central core gravity was reduced and could not hold the mass ,which Is galaxy expansion

May 24, 2016
Which is mechanically possible if the CCM is a quantum particle mass made from taking neutrons and protons apart, after stripping their orbiting electrons to build its gravity held electron field , building an induction environment,

May 24, 2016
Whoa, cool, a new galaxy type. The Coma Cluster is where one would expect these to show up, considering it's densely populated.

What's really interesting here is that the initial discovery was made with an amateur-class OTA; I personally own three OTAs larger than 100mm. (One is a 101, one is a 127, both APO refractors, and the third is a 235mm reflector.) This argues that crowdsourcing of UDG discovery might be a successful endeavor in the amateur astronomy community. A lot of data could be gathered very quickly, giving coordinates that can be followed up with much larger professional installations. Some smart undergraduate should take this on and make their name.

May 26, 2016
How do Beasley's team conclude that VCC 1287 is in Virgo, all the more in Virgo cluster when it is located 1* north of Markarian chain, 42' from the Northern boundary of Virgo and well in Coma Berenices ? Even if it shows the same speed as galaxies from the Virgo association, it belongs to Coma or I am wrong ? Coord. ra=12.50624877301382, dec=13.97764159141237 is well in coma.

May 26, 2016
What's really interesting here is that the initial discovery was made with an amateur-class OTA;

The B/W picture was recorded by an amateur astronomer from Antares Obs using a 100 mm refractor

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more