Stars in the making: Research may sharpen view of developing universe

Aug 03, 2012 By Peter Reuell

For decades, scientists have sought to develop newer and more powerful ways to peer into the far reaches of the cosmos and into the early days of the universe, both with optical telescopes and powerful radio telescopes.

But a new paper, published last month in Nature and authored by Eli Visbal, a graduate student in Harvard’s Physics Department, with colleagues from the California Institute of Technology and Tel Aviv University, suggests that it may be far easier than commonly thought to peer deep into the universe’s history and observe the telltale signs of the first stars and galaxies.

Using powerful computer models, Visbal and colleagues simulated how stars formed in the universe’s infancy clump together into massive web-like structures. The key to the simulation, he said, was the inclusion of a 2010 discovery that normal matter, such as hydrogen gas, and dark matter — which makes up more than 80 percent of the universe — move through the universe at different speeds.

Those web-like structures, Visbal said, hold the prospect of greatly simplifying the process of detecting the signatures of the earliest stars in the universe.

“This is the first simulation of the three-dimensional distribution of stars that includes this relative velocity effect,” Visbal said. “What was clear from looking at our simulation was that, based on the large fluctuations in these ‘web’ formations, observing early stars should be far easier than we previously thought.”

Astronomers hunting for early stars aren’t hunting for the actual stars, but signatures of their existence. Among the best such signatures, Visbal said, is the 21-centimeter wavelength emission given off by hydrogen gas as it is warmed by the stars.

The challenge, however, is that the radiation from early stars is often obscured by background radiation produced by the Milky Way and other nearby galaxies.

The web-like structures identified in Visbal’s simulations, however, suggest that astronomers should be able to identify early stars by searching for fluctuations in the 21-centimeter emission. By identifying areas that emit high amounts of the radiation, astronomers should be able to spot early stars.

One factor, Visbal explained, is the sheer size — as much as 400 million light-years across — of the “web” of early stars. To observe a region that size, astronomers need only about two-thirds of a degree of angular resolution.

“When you increase the relative velocity effect, you get these huge regions where star formation is suppressed,” Visbal explained. “The result is that you don’t need particularly high-resolution telescopes to make these observations. That’s why it’s more feasible to see these structures.”

Based on the simulations, Visbal said, astronomers should be able to study stars formed when the universe was just 180 million years old. (The universe is 14.6 billion years old.) Current techniques allow astronomers to see objects formed at 800 million years.

Detecting such , Visbal said, could be a critical step in a wider understanding of the universe then and now.

“Structure in the universe is formed hierarchically,” he said. “This means that larger objects are built from the mergers of smaller ones. So, in some sense, if we are able to determine how the first stars and galaxies formed, we can understand the building blocks which make up large objects in the current .”

Researchers will now turn to making real-world observations to determine if the simulation’s predictions are accurate.

“Radio observatories are being used right now to observe 21-centimeter emission from much later times,” Visbal said. “Similar facilities, designed to observe different frequencies, will need to be constructed to detect the signature of the first stars.”

Explore further: Is the universe finite or infinite?

add to favorites email to friend print save as pdf

Related Stories

How the Universe escaped its 'dark ages'

Jun 11, 2012

(Phys.org) -- An international team of astronomers have uncovered an important clue about how the Universe emerged from its ‘dark ages’ some 13 billion years ago. By looking at nearby galaxies, they ...

Could primordial black holes be dark matter?

Sep 21, 2011

(PhysOrg.com) -- “We know that about 25% of the matter in the universe is dark matter, but we don’t know what it is,” Michael Kesden tells PhysOrg.com. “There are a number of different theories about what da ...

Recommended for you

Is the universe finite or infinite?

Mar 27, 2015

Two possiblities exist: either the Universe is finite and has a size, or it's infinite and goes on forever. Both possibilities have mind-bending implications.

'Teapot' nova begins to wane

Mar 27, 2015

A star, or nova, has appeared in the constellation of Sagittarius and, even though it is now waning, it is still bright enough to be visible in the sky over Perth through binoculars or a telescope.

Dark matter is darker than once thought

Mar 27, 2015

This panel of images represents a study of 72 colliding galaxy clusters conducted by a team of astronomers using NASA's Chandra X-ray Observatory and Hubble Space Telescope. The research sets new limits on ...

Galaxy clusters collide—dark matter still a mystery

Mar 26, 2015

When galaxy clusters collide, their dark matters pass through each other, with very little interaction. Deepening the mystery, a study by scientists at EPFL and the University of Edinburgh challenges the ...

Using 19th century technology to time travel to the stars

Mar 26, 2015

In the late 19th century, astronomers developed the technique of capturing telescopic images of stars and galaxies on glass photographic plates. This allowed them to study the night sky in detail. Over 500,000 ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.