Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA's Hubble and Chandra Discover Dark Matter Is Not as Sticky as Once Thought

31.03.2015

Astronomers using observations from NASA's Hubble Space Telescope and Chandra X-ray Observatory have found that dark matter does not slow down when colliding with each other. This means that it interacts with itself even less than previously thought. Researchers say this finding narrows down the options for what this mysterious substance might be.

Dark matter is a transparent form of matter that makes up most of the mass in the universe. Because dark matter does not reflect, absorb, or emit light, it can only be traced indirectly, such as by measuring how it warps space through gravitational lensing, where the light from distant sources is magnified and distorted by the gravitational effects of dark matter.


NASA/ESA/STScI/CXC, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland; Univ. of Edinburgh, UK), R. Massey (Durham Univ., UK), T. Kitching (Univ. College London, UK), and A. Taylor and E. Tittley (Univ. of Edinburgh, UK)

This collage shows images of six different galaxy clusters taken with NASA's Hubble Space Telescope and Chandra X-ray Observatory. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. A total of 72 large cluster collisions were studied. Using visible-light images from Hubble, the team was able to map the post-collision distribution of stars and also of the dark matter (colored in blue), which was traced through its gravitational lensing effects on background light. Chandra was used to see the X-ray emission from impacted gas (pink). The team determined that dark matter interacts with itself and everything else even less than previously thought. The clusters shown here are, from left to right and top to bottom: MACS J0416.1-2403, MACS J0152.5-2852, MACS J0717.5+3745, Abell 370, Abell 2744, and ZwCl 1358+62.


NASA/ESA/D. Harvey/EPFL/R. Massey/Durham U./T. Kitching/U. College London/A. Taylor, E. Tittley/U. Edinburgh/HST SM4 ERO Team/ST-ECF, ESO/D. Coe/STScI/J. Merten/Heidelberg/Bologna/HST Frontier Fields/H. Ebeling/U. Hawaii/J.-P. Kneib/LAM/J. Richard/Caltech

This collage shows images of six different galaxy clusters taken with NASA's Hubble Space Telescope. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. Seventy-two large cluster collisions were studied in total. Using visible-light images from Hubble, the team was able to map the post-collision distribution of stars and also of the dark matter (colored in blue), which was traced through its gravitational lensing effects on background light. The team determined that dark matter interacts with itself less than previously thought. The clusters shown here are, from left to right and top to bottom: MACS J0416.1-2403, MACS J0152.5-2852, MACS J0717.5+3745, Abell 370, Abell 2744, and ZwCl 1358+62.

The two space observatories were used to study how dark matter in clusters of galaxies behaves when the clusters collide. Hubble was used to map the post-collision distribution of stars and dark matter, which was traced through its gravitational lensing effects on background light. Chandra was used to see the X-ray emission from the colliding gas. The results will be published in the journal Science on March 27.

"Dark matter is an enigma we have long sought to unravel," said John Grunsfeld, assistant administrator of NASA's Science Mission Directorate in Washington. "With the combined capabilities of these great observatories, both in extended mission, we are ever closer to understanding this cosmic phenomenon."

To learn more about dark matter, researchers can study it in a way similar to experiments on visible matter -- by watching what happens when it bumps into celestial objects. An excellent natural laboratory for this analysis can be found in collisions between galaxy clusters.

Galaxy clusters are made of three main ingredients: galaxies, clouds of gas, and dark matter. During collisions, the clouds of gas enveloping the galaxies crash into each other and slow down or stop. The galaxies are much less affected by the drag from the gas and, because of the huge gaps between the stars within them, do not have a slowing effect on each other.

"We know how gas and galaxies react to these cosmic crashes and where they emerge from the wreckage. Comparing how dark matter behaves can help us to narrow down what it actually is," explained David Harvey of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, lead author of the new study.

Harvey and his team used data from Hubble and Chandra to study 72 large cluster collisions. The collisions happened at different times, and are seen from different angles -- some from the side, and others head-on.

The team found that, like the galaxies, the dark matter continued straight through the violent collisions without slowing down relative to the galaxies. Because galaxies pass through unimpeded, if astronomers observe a separation between the distribution of the galaxies and the dark matter then they know it has slowed down. If the dark matter does slow, it will drag and lie somewhere between the galaxies and the gas, which tells researchers how much it has interacted.

The leading theory is that dark matter particles spread throughout the galaxy clusters do not frequently bump into each other. The reason the dark matter doesn't slow down is because not only does it not interact with visible particles, it also infrequently interacts with other dark matter. The team has measured this "self-interaction" and found it occurs even less frequently than previously thought.

"A previous study had seen similar behavior in the Bullet Cluster," said team member Richard Massey of Durham University, U.K. "But it's difficult to interpret what you're seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on."

By finding that dark matter interacts with itself even less than previously thought, the team has successfully narrowed down the properties of dark matter. Particle physics theorists now have a smaller set of unknowns to work with when building their models.

"It is unclear how much we expect dark matter to interact with itself because dark matter is already going against everything we know, said Harvey. "We know from previous observations that it must interact with itself reasonably weakly, however this study has now placed it below that of two protons interacting with one another -- which is one theory for dark matter." Harvey said that the results suggest that dark matter is unlikely to be only a kind of dark proton. If dark matter scattered like protons do with one another (electrostatically) it would have been detected. "This challenges the idea that there exists 'dark photons,' the dark matter equivalent of photons," he said.

Dark matter could potentially have rich and complex properties, and there are still several other types of interactions to study. These latest results rule out interactions that create a strong frictional force, causing dark matter to slow down during collisions. Other possible interactions could make dark matter particles bounce off each other like billiard balls, causing dark matter particles to be ejected from the clouds by collisions or for dark matter blobs to change shape. The team will be studying these next.

To further increase the number of collisions that can be studied, the team is also looking to study collisions involving individual galaxies, which are much more common.

"There are still several viable candidates for dark matter, so the game is not over, but we are getting nearer to an answer," concludes Harvey. "These
'astronomically large' particle colliders are finally letting us glimpse the dark world all around us but just out of reach."

For images and more information about the Hubble Space Telescope, visit:

http://hubblesite.org/news/2015/10

http://www.nasa.gov/hubble

http://www.spacetelescope.org/news/heic1506

For more information about Chandra, visit:
http://www.nasa.gov/mission_pages/chandra/main/index.html

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington, D.C. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Contact Information
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Georgia Bladon
ESA/Hubble, Garching, Germany
011-44-7816-291261
gbladon@partner.eso.org

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu

David Harvey
EPFL, Lausanne, Switzerland; University of Edinburgh, Edinburgh, UK
011-41-22-3792475
david.harvey@epfl.ch

Richard Massey
Durham University, Durham, UK
011-44-7740-648080
r.j.massey@durham.ac.uk

Ray Villard
News Chief
villard@stsci.edu
Phone: 410-338-4514

Ray Villard | newswise

More articles from Physics and Astronomy:

nachricht Applicability of dynamic facilitation theory to binary hard disk systems
08.12.2016 | Nagoya Institute of Technology

nachricht Will Earth still exist 5 billion years from now?
08.12.2016 | KU Leuven

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>