Subscribe to our free daily newsletters
  Space Travel News  




Subscribe to our free daily newsletters



STELLAR CHEMISTRY
A new look at the nature of dark matter
by Staff Writers
Santa Cruz de Tenerife, Spain (SPX) Mar 07, 2017


The microlensing object in the foreground galaxy could be a star (as depicted), a primordial black hole, or any other compact object. Image courtesy NASA/Jason Cowan (Astronomy Technology Center).

The nature of the dark matter which apparently makes up 80% of the mass of the particles in the universe is still one of the great unsolved mysteries of present day sciences.

The lack of experimental evidence, which could allow us to identify it with one or other of the new elementary particles predicted by the theorists, as well as the recent discovery of gravitational waves coming from the merging of two black holes (with masses some 30 times that of the Sun) by LIGO the Laser Interferometer Gravitational Wave Observatory) have revived interest in the possibility that dark matter might take the form of primordial black holes with masses between 10 and 1000 times that of the Sun.

Primordial black holes, which would have originated in high density fluctuations of matter during the first moments of the Universe, are in principle very interesting. As opposed to those which form from stars, whose abundance and masses are limited by models of stellar formation and evolution, primordial black holes could exist with a wide range of masses and abundances.

They would be found in the halos of galaxies, and the occasional meeting between two of them having masses 30 times that of the Sun, followed by a subsequent merger, might have given rise to the gravitational waves detected by LIGO.

"Microlensing effect"
If there were an appreciable number of black holes in the halos of galaxies, some of them intercept the light coming towards us from a distant quasar. Because of their strong gravitational fields, their gravity could concentrate the rays of light, and cause an increase in the apparent brightness of the quasar.

This effect, known as "gravitational microlensing" is bigger the bigger the mass of the black hole, and the probability of detecting it would be bigger the more the presence of these black holes. So although the black holes themselves cannot be directly detected, they would be detected by increases in the brightness of observed quasars.

On this assumption, a group of scientists has used the microlensing effect on quasars to estimate the numbers of primordial black holes of intermediate mass in galaxies. The study, led by the researcher at the Instituto de Astrofisica de Canarias (IAC) and the University of La Laguna (ULL), Evencio Mediavilla Gradolph, shows that normal stars like the Sun cause the microlensing effects, thus ruling out the existence of a large population of primordial black holes with intermediate mass.

Computer simulations
Using computer simulations, they have compared the rise in brightness, in visible light and in X-rays, of 24 distant quasars with the values predicted by the microlensing effect. They have found that the strength of the effect is relatively low, as would be expected from objects with a mass between 0.05 and 0.45 times that of the Sun, and well below that of intermediate mass black holes.

In addition they have estimated that these microlenses form roughly 20% of the total mass of a galaxy, equivalent to the mass expected to be found in stars. So their results show that, with high probability, it is normal stars and not primordial intermediate mass black holes which are responsible for the observed microlensing.

"This study implies "says Evencio Mediavilla, "that it is not at all probable that black holes with masses between 10 and 100 times the mass of the Sun make up a significant fraction of the dark matter". For that reason the black holes whose merging was detected by LIGO were probably formed by the collapse of stars, and were not primordial black holes".

Astronomers participating in this research include Jorge Jimenez-Vicente and Jose Calderon-Infante (University of Granada) and Jose A. Munoz Lozano, and Hector Vives-Arias, (University of Valencia).

STELLAR CHEMISTRY
Yale-led team puts dark matter on the map
New Haven CT (SPX) Mar 03, 2017
A Yale-led team has produced one of the highest-resolution maps of dark matter ever created, offering a detailed case for the existence of cold dark matter - sluggish particles that comprise the bulk of matter in the universe. The dark matter map is derived from Hubble Space Telescope Frontier Fields data of a trio of galaxy clusters that act as cosmic magnifying glasses to peer into older ... read more

Related Links
Instituto de Astrofisica de Canarias
Stellar Chemistry, The Universe And All Within It


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment on this article using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

STELLAR CHEMISTRY
STELLAR CHEMISTRY
New evidence for a water-rich history on Mars

Humans May Quickly Evolve on Mars, Biologist Claims

NASA Orbiter Steers Clear of Mars Moon Phobos

Remnants of a mega-flood on Mars

STELLAR CHEMISTRY
India's Moon Mission on 2018 Target, Says ISRO Chief

An Epic Lunar Experience Lands at Space Center Houston

India Takes Russian Help to Analyze Chemical Composition of Lunar Surface

Complete Lunar-cy: The Earth Has Sprayed the Moon With Oxygen for Billennia

STELLAR CHEMISTRY
Juno to remain in current orbit at Jupiter

Europa Flyby Mission Moves into Design Phase

NASA receives science report on Europa lander concept

New Horizons Refines Course for Next Flyby

STELLAR CHEMISTRY
Hunting for giant planet analogs in our own backyard

Biochemical 'fossil' shows how life may have emerged without phosphate

Faraway Planet Systems Are Shaped Like the Solar System

The missing link in how planets form

STELLAR CHEMISTRY
Space squadron supports record-breaking satellites launch

Blue Origin shares video of New Glenn rocket

Europe launches fourth Earth monitoring satellite

Elon Musk: tech dreamer reaching for sun, moon and stars

STELLAR CHEMISTRY
China launches experiment satellite "TK-1"

Riding an asteroid: China's next space goal

China's 1st cargo spacecraft to make three rendezvous with Tiangong-2

China to launch space station core module in 2018

STELLAR CHEMISTRY
Earth is bombarded at random, crater study shows

Asteroid Split in Two and, Years Later, Developed Tails

NASA study hints at possible change in water 'fingerprint' of comet

Researchers aim to measure risk of exploding asteroids




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement