Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers find part of universe’s missing matter

03.02.2005


Found: 7 percent of the mass of the universe. Missing since: 10 billion years ago.

Consider one more astronomical mystery solved. Scientists have located a sizeable chunk of the universe that seemed to be missing since back when the stars first formed. It’s floating in super-hot rivers of gas, invisible to the naked eye, surrounding galaxies like our own. And a completely different kind of mystery matter -- dark matter -- may have put it there. The results appear in the current issue of the journal Nature.

To make this latest discovery, astronomers at Ohio State University and their colleagues used NASA’s Chandra X-ray Observatory to take the highest-quality spectrum of its type ever made. Though astronomers had previously detected the rivers of gas with X-ray telescopes, this is the first time that the gas has been studied in enough detail to calculate how much of it is out there. The amount of gas matches the amount of material that went missing 10 billion years ago, said Smita Mathur, associate professor of astronomy at Ohio State.



She and doctoral student Rik Williams did this work with astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA), the University of California, Berkeley, the Instituto de Astronomia in Mexico, and the Massachusetts Institute of Technology. The lead author on the paper is Fabrizio Nicastro of CfA. According to current theories, when the universe began, it contained a certain amount of normal matter, a cache of protons and neutrons that today make up all normal atoms -- “stuff” as we know it.

Astronomers can use optical telescopes to look back in time and see what happened to the normal atoms, called baryons. Around 10 billion years ago, when half of the baryons became stars and galaxies and lit up the sky, the other half just seemed to disappear.

This new study shows that the missing baryons are still out there, Mathur said, they’re just floating in gas that is too hot to see with an optical telescope. The gas that surrounds our galaxy, for example, is 100 times hotter than the sun -- so hot that it shines in high-energy X-rays instead of lower-energy visible light.

In 2002, Mathur and her colleagues used Chandra’s X-ray telescope to gather the first evidence that the gas was made of baryons. The image they obtained was a spectrum, a measurement of the different wavelengths of X-rays emanating from the material. But to prove that there was enough material there to account for the all the missing baryons, they knew they needed to take a better spectrum with the telescope. “Those first results were tantalizing, but not foolproof. The signal-to-noise ratio in the spectrum was just not good enough,” Mathur said.

They needed a bright light source to pump up the signal, one located on the other side of the gas as viewed from Earth, so that the light shined directly through the gas. They found their source in a quasar, located in the constellation Ursa Major -- the Big Dipper. Astronomers believe that quasars are galaxies with very massive black holes in the center. The black holes in quasars don’t just suck material in, they also shoot material out in a high-speed jet. The jet glows brightly, and the result is an intense beam of light -- exactly what Mathur and her colleagues needed to take their picture.

The astronomers decided to use the light from Markarian 421, one of the brightest quasars known. On two days -- one in October 2002 and another in July 2003 -- when Markarian 421 was at its brightest and the beam of light was pointing right at Earth, Mathur’s team took two very high quality X-ray spectra of the intervening gas. Judging by the high signal-to-noise ratio of the data, the astronomers believe that one of their images is the best X-ray spectrum ever taken.

That spectrum isn’t what most people would consider a pretty picture -- it’s really just a graph of energy levels of light that penetrated the gas -- but to Mathur it’s absolutely beautiful, because it proved definitively that there are enough baryons -- “normal” atoms -- out there to account for the missing mass. “This is such a wonderful spectrum that there is just no doubt about it,” she said. Once they had the new spectra, the astronomers were able to calculate the density of baryons in the gas, and confirmed that the amount of material matched the missing matter they were searching for.

As to how the missing baryons ended up where they are, Mathur suspects that they were drawn there by the gravity of a different kind of matter, known as dark matter. Astronomers know that some unseen material provides most of the gravity of the universe, though they disagree on what dark matter is actually made of. If Mathur and her colleagues are right, then their finding supports a dramatic theory: that dark matter provides a kind of backbone to the universe, where the structure of normal matter like galaxies follows an underlying structure of dark matter.

This research was sponsored by NASA-Chandra grants and NASA’s Long-Term Space Astrophysics program.

Smita Mathur | EurekAlert!
Further information:
http://www.osu.edu

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>