Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First Stars, Galaxies Formed More Rapidly Than Expected

07.09.2012
Analysis of data from the National Science Foundation’s South Pole Telescope, for the first time, more precisely defines the period of cosmological evolution when the first stars and galaxies formed and gradually illuminated the universe. The data indicate that this period, called the epoch of reionization, was shorter than theorists speculated — and that it ended early.
“We find that the epoch of reionization lasted less than 500 million years and began when the universe was at least 250 million years old,” said Oliver Zahn, a postdoctoral fellow at the Berkeley Center for Cosmological Physics at the University of California, Berkeley, who led the study. “Before this measurement, scientists believed that reionization lasted 750 million years or longer, and had no evidence as to when reionization began.”

The findings by Zahn, his colleagues at UChicago’s Kavli Institute for Cosmological Physics and elsewhere have been published in a pair of papers appearing in the Sept. 1, 2012 issue of the Astrophysical Journal. Their latest results are based on a new analysis that combines measurements taken by the South Pole Telescope at three frequencies, and extends these measurements to a larger area covering approximately 2 percent of the sky. The 10-meter South Pole Telescope operates at millimeter wavelengths to make high-resolution images of the cosmic microwave background (CMB), the light left over from the big bang.

“Studying the epoch of reionization is important because it represents one of the few ways by which we can study the first stars and galaxies,” said study co-author John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics.
Before the first stars formed, most matter in the universe took the form of neutral hydrogen atoms. The radiation from the first stars transformed the neutral gas into an electron-proton plasma. Observations with the Wilkinson Microwave Anisotropy Probe satellite of polarized signals in the CMB indicate that this epoch occurred nearly 13 billion years ago, but these observations give no indication of when the epoch began or how long it lasted.

The first stars that formed were probably 30 to 300 times more massive than the sun and millions of times as bright, burning for only a few million years before exploding. The energetic ultraviolet light from these stars was capable of splitting hydrogen atoms back into electrons and protons, thus ionizing them.

Scientists believe that during reionization, the first galaxies to form ionized “bubbles” in the neutral gas surrounding them. Electrons in these bubbles would scatter with light particles from the cosmic microwave background. This would create small hot and cold spots in the CMB depending on whether a bubble is moving toward or away from Earth. A longer epoch of reionization would create more bubbles, leading to a larger signal in the CMB.

The epoch’s short duration indicates that reionization was more explosive than scientists had previously thought. It suggests that massive galaxies played a key role in reionization, because smaller galaxies would have formed much earlier. Rapid reionization also argues against many proposed astrophysical phenomena that would slow the process.

This is only the beginning of what astronomers expect to learn about reionization from the South Pole Telescope. The current results are based on only the first third of the telescope’s full survey. Additional work is under way to combine South Pole Telescope maps with ones made by the Herschel satellite to further increase sensitivity to the reionization signal.

“We expect to measure the duration of reionization to within 50 million years with the current survey,” said study co-author Christian Reichardt, a Berkeley astrophysicist. “With planned upgrades to the instrument, we hope to improve this even further in the next five years.”

The 280-ton South Pole Telescope stands 75 feet tall and is the largest astronomical telescope ever built in Antarctica’s clear, dry air. Sited at the National Science Foundation’s Amundsen-Scott South Pole station at the geographic South Pole, it stands at an elevation of 9,300 feet on the polar plateau. Because of its location at the Earth’s axis, it can conduct long-term observations of a single patch of sky.

UChicago leads the South Pole Telescope collaboration, which includes research groups from Argonne National Laboratory, Cardiff University, Case Western Reserve University, Harvard University, Ludwig-Maximilians-Universitat, Smithsonian Astrophysical Observatory, McGill University, University of California at Berkeley, University of California at Davis, University of Colorado at Boulder, University of Michigan and individual scientists at several other institutions.

The South Pole Telescope is primarily funded by the NSF’s Office of Polar Programs. Partial support also is provided by the NSF-funded Physics Frontier Center of UChicago’s Kavli Institute for Cosmological Physics, the Kavli Foundation, and the Gordon and Betty Moore Foundation.

Steve Koppes | Newswise Science News
Further information:
http://www.uchicago.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 >>>