Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCI scientists discover minimum mass for galaxies

01.09.2008
Breakthrough helps researchers better understand mysterious dark matter

By analyzing light from small, faint galaxies that orbit the Milky Way, UC Irvine scientists believe they have discovered the minimum mass for galaxies in the universe – 10 million times the mass of the sun.

This mass could be the smallest known "building block" of the mysterious, invisible substance called dark matter. Stars that form within these building blocks clump together and turn into galaxies.

Scientists know very little about the microscopic properties of dark matter, even though it accounts for approximately five-sixths of all matter in the universe.

"By knowing this minimum galaxy mass, we can better understand how dark matter behaves, which is essential to one day learning how our universe and life as we know it came to be," said Louis Strigari, lead author of this study and a McCue Postdoctoral Fellow in the Department of Physics and Astronomy at UCI.

Study results are published Aug. 28 in the journal Nature.

Dark matter governs the growth of structure in the universe. Without it, galaxies like our own Milky Way would not exist. Scientists know how dark matter's gravity attracts normal matter and causes galaxies to form. They also suspect that small galaxies merge over time to create larger galaxies such as our Milky Way.

The smallest known galaxies, called dwarf galaxies, vary greatly in brightness, from 1,000 times the luminosity of the sun to 10 million times the luminosity of the sun. At least 22 of these dwarf galaxies are known to orbit the Milky Way. UCI scientists studied 18 of them using data obtained with the Keck telescope in Hawaii and the Magellan telescope in Chile, with the goal of calculating their masses. By analyzing stars' light in each galaxy, they determined how fast the stars were moving. Using those speeds, they calculated the mass of each galaxy.

The researchers expected the masses to vary, with the brightest galaxy weighing the most and the faintest galaxy weighing the least. But surprisingly all dwarf galaxies had the same mass – 10 million times the mass of the sun.

Manoj Kaplinghat, a study co-author and physics and astronomy assistant professor at UCI, explains this finding using an analogy in which humans play the role of dark matter.

"Suppose you are an alien flying over Earth and identifying urban areas from the concentration of lights in the night. From the brightness of the lights, you may surmise, for example, that more humans live in Los Angeles than in Mumbai, but this is not the case," Kaplinghat said. "What we have discovered is more extreme and akin to saying that all metro areas, even those that are barely visible at night to the aliens, have a population of about 10 million."

Since dwarf galaxies are mostly dark matter – the ratio of dark matter to normal matter is as large as 10,000 to one – the minimum-mass discovery reveals a fundamental property of dark matter.

"We are excited because these galaxies are virtually invisible, yet contain a tremendous amount of dark matter," said James Bullock, a study co-author and director of UCI's Center for Cosmology. "This helps us better understand the particle that makes up dark matter, and it teaches us something about how galaxies form in the universe."

The scientists say clumps of dark matter may exist that contain no stars. The only dark matter clumps they can detect right now are those that are lit by stars.

Scientists hope to learn about dark matter's microscopic properties when the Large Hadron Collider in Switzerland becomes operational later this year. The device will accelerate two beams of nuclei in a ring in opposite directions and then slam them together to recreate conditions just after the Big Bang. By doing this, scientists hope to create the dark matter particle in the lab for the first time.

###

Several UCI physicists are working on this international project. Joining UCI scientists on the galaxy study were Joshua Simon of the California Institute of Technology, Marla Geha of Yale University, Beth Willman of the Harvard-Smithsonian Center for Astrophysics, and Matthew Walker of the University of Cambridge.

The research was funded by a grant from the National Science Foundation and a donation from Gary McCue to the UCI Center for Cosmology.

About the University of California, Irvine: The University of California, Irvine is a top-ranked university dedicated to research, scholarship and community service. Founded in 1965, UCI is among the fastest-growing University of California campuses, with more than 27,000 undergraduate and graduate students and nearly 2,000 faculty members. The third-largest employer in dynamic Orange County, UCI contributes an annual economic impact of $3.6 billion. For more UCI news, visit www.today.uci.edu.

News Radio: UCI maintains on campus an ISDN line for conducting interviews with its faculty and experts. The use of this line is available free-of-charge to radio news programs/stations who wish to interview UCI faculty and experts. Use of the ISDN line is subject to availability and approval by the university.

UCI maintains an online directory of faculty available as experts to the media. To access, visit www.today.uci.edu/experts. For UCI breaking news, visit www.zotwire.uci.edu.

Jennifer Fitzenberger | EurekAlert!
Further information:
http://www.uci.edu
http://www.today.uci.edu/experts
http://www.zotwire.uci.edu

More articles from Physics and Astronomy:

nachricht Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun
18.04.2019 | University of Warwick

nachricht In vivo super-resolution photoacoustic computed tomography by localization of single dyed droplets
18.04.2019 | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences

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: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>