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 NASA laser communications to provide Orion faster connections
30.03.2017 | NASA/Goddard Space Flight Center

nachricht Pinball at the atomic level
30.03.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

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: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>