Very Large Array gives deep, detailed image of distant Universe

Apr 30, 2013
VLA Image of Small Portion of Extragalactic Space: About 2,000 discrete objects are identified in this VLA image of the distant Universe. This entire image constitutes only about one-millionth of the entire sky. Credit: Condon, et al., NRAO/AUI/NSF

(Phys.org) —Staring at a small patch of sky for more than 50 hours with the ultra-sensitive Karl G. Jansky Very Large Array (VLA), astronomers have for the first time identified discrete sources that account for nearly all the radio waves coming from distant galaxies. They found that about 63 percent of the background radio emission comes from galaxies with gorging black holes at their cores and the remaining 37 percent comes from galaxies that are rapidly forming stars.

"The sensitivity and resolution of the VLA, following its decade-long upgrade, made it possible to identify the specific objects responsible for nearly all of the radio background emission coming from beyond our own ," said Jim Condon, of the (NRAO). "Before we had this capability, we could not detect the numerous faint sources that produce much of the background emission," he added.

Previous studies had measured the amount of radio emission coming from the distant Universe, but had not been capable of attributing all the to specific objects. In earlier observations, emission from two or more faint objects often was blurred or blended into what appeared to be a single, stronger source of radio waves.

"Advancing technology has revealed more and more of the Universe to us over the past few decades, and our study shows individual objects that account for about 96 percent of the background radio emission coming from the ," Condon said. "The VLA now is a million times more sensitive than the that made landmark surveys of the sky in the 1960s," he added.

In February and March of 2012, Condon and his colleagues studied a region of sky that previously had been observed by the original, pre-upgrade, VLA, and by the , which observes infrared light. They carefully analyzed and processed their data, then produced an image that showed the individual, radio-emitting objects within their field of view.

Their field of view, in the constellation Draco, encompassed about one-millionth of the whole sky. In that region, they identified about 2,000 discrete radio-emitting objects. That would indicate, the scientists said, that there are about 2 billion such objects in the whole sky. These are the objects that account for 96 percent of the background radio emission. However, the researchers pointed out, the remaining 4 percent of the could be coming from as many as 100 billion very faint objects.

Further analysis allowed the scientists to determine which of the objects are galaxies containing massive central black holes that are actively consuming surrounding material and which are galaxies undergoing rapid bursts of star formation. Their results indicate that, as previously proposed, the two types of galaxies evolved at the same rate in the early Universe.

"What radio astronomers have accomplished over the past few decades is analogous to advancing from the early Greek maps of the world that showed only the Mediterranean basin to the maps of today that show the whole world in exquisite detail," Condon said.

Condon worked with William Cotton, Edward Fomalont, Kenneth Kellermann, and Rick Perley of NRAO; Neal Miller of the University of Maryland; and Douglas Scott, Tessa Vernstrom, and Jasper Wall of the University of British Columbia. The researchers published their work in the Astrophysical Journal.

Explore further: Image: NGC 6872 in the constellation of Pavo

Related Stories

Radio galaxies in the distant universe

Jun 26, 2012

(Phys.org) -- For over a decade astronomers have been probing a region of the northern sky, not far from the handle of the Big Dipper, that is relatively free of bright stars and the diffuse glow of the Milky ...

LOFAR discovers new giant galaxy in all-sky survey

Mar 20, 2013

A team of astronomers led by ASTRON astronomer Dr. George Heald has discovered a previously unknown gigantic radio galaxy, using initial images from a new, ongoing all-sky radio survey. The galaxy was found ...

Fireworks in the early universe

Sep 28, 2012

Galaxies in the early universe grew fast by rapidly making new stars. Such prodigious star formation episodes, characterized by the intense radiation of the newborn stars, were often accompanied by fireworks ...

Cosmic radio beacons

Nov 08, 2010

(PhysOrg.com) -- Because all cosmic objects evolve with time, astronomers sometimes have a difficult time deciding if two sources that seem different are actually related but just in different stages of life. ...

Recommended for you

Image: NGC 6872 in the constellation of Pavo

9 hours ago

This picture, taken by the NASA/ESA Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2), shows a galaxy known as NGC 6872 in the constellation of Pavo (The Peacock). Its unusual shape is caused ...

Measuring the proper motion of a galaxy

10 hours ago

The motion of a star relative to us can be determined by measuring two quantities, radial motion and proper motion. Radial motion is the motion of a star along our line of sight. That is, motion directly ...

Gravitational waves according to Planck

Sep 22, 2014

Scientists of the Planck collaboration, and in particular the Trieste team, have conducted a series of in-depth checks on the discovery recently publicized by the Antarctic Observatory, which announced last ...

Infant solar system shows signs of windy weather

Sep 22, 2014

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have observed what may be the first-ever signs of windy weather around a T Tauri star, an infant analog of our own Sun. This may help ...

Finding hints of gravitational waves in the stars

Sep 22, 2014

Scientists have shown how gravitational waves—invisible ripples in the fabric of space and time that propagate through the universe—might be "seen" by looking at the stars. The new model proposes that ...

How gamma ray telescopes work

Sep 22, 2014

Yesterday I talked about the detection of gamma ray bursts, intense blasts of gamma rays that occasionally appear in distant galaxies. Gamma ray bursts were only detected when gamma ray satellites were put ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

wiyosaya
not rated yet Apr 30, 2013
"Advancing technology has revealed more and more of the Universe to us over the past few decades, and our study shows individual objects that account for about 96 percent of the background radio emission coming from the distant Universe,"

Now that such a high resolution study is possible, does this call into question the nature of the cosmic background radiation?
Q-Star
2 / 5 (4) Apr 30, 2013
Now that such a high resolution study is possible, does this call into question the nature of the cosmic background radiation?


Not at all, it's providing confirmation of how the CMB has been interpreted and modeled. An amazingly good fit.
Fleetfoot
1 / 5 (1) May 01, 2013
ALMA measures a lower frequency background. There's a graphical summary of the various backgrounds here:

http://www.isas.j...g_01.gif

The radio component is on the far left below the CMBR.