Cosmic Lens Reveals Distant Galactic Violence

Oct 20, 2008
Radio waves from carbon monoxide gas in the distant galaxy (left) were bent by the gravitational effect of another galaxy directly between the distant object and Earth (right). The nearly-perfect alignment caused the distant object to appear as a ring when seen from Earth. This graphic shows how the distant object would appear as one moves from Earth toward the lensing galaxy. Some of the waves are Doppler shifted by the motions of the gas in the galaxy, and this is indicated by the colors. Green indicates "stationary" gas; red indicates gas moving away from us, and blue indicates gas moving toward us with respect to the rest of the galaxy. Image: Bill Saxton, NRAO/AUI/NSF

( -- By cleverly unraveling the workings of a natural cosmic lens, astronomers have gained a rare glimpse of the violent assembly of a young galaxy in the early Universe. Their new picture suggests that the galaxy has collided with another, feeding a supermassive black hole and triggering a tremendous burst of star formation.

The astronomers used the National Science Foundation's Very Large Array (VLA) radio telescope to look at a galaxy more than 12 billion light-years from Earth, seen as it was when the Universe was only about 15 percent of its current age. Between this galaxy and Earth lies another distant galaxy, so perfectly aligned along the line of sight that its gravity bends the light and radio waves from the farther object into a circle, or "Einstein Ring."

This gravitational lens made it possible for the scientists to learn details of the young, distant galaxy that would have been unobtainable otherwise.

"Nature provided us with a magnifying glass to peer into the workings of a nascent galaxy, providing an exciting look at the violent, messy process of building galaxies in the early history of the Universe," said Dominik Riechers, who led this project at the Max Planck Institute for Astronomy in Germany and now is a Hubble Fellow at the California Institute of Technology (Caltech).

The new picture of the distant galaxy, dubbed PSS J2322+1944, shows a massive reservoir of gas, 16,000 light-years in diameter, that contains the raw material for building new stars. A supermassive black hole is voraciously eating material, and new stars are being born at the rate of nearly 700 Suns per year. By comparison, our Milky Way Galaxy produces the equivalent of about 3-4 Suns per year.

The black hole appears to be near the edge, rather than at the center, of the giant gas reservoir, indicating, the astronomers say, that the galaxy has merged with another.

"This whole picture, of massive galaxies and supermassive black holes assembling themselves through major galaxy mergers so early in the Universe, is a new paradigm in galaxy formation. This gravitationally lensed system allows us to see this process in unprecedented detail," said Chris Carilli, of the National Radio Astronomy Observatory.

In 2003, astronomers studied PSS J2322+1944, finding the Einstein Ring by observing radio waves emitted by molecules of Carbon Monoxide (CO). When astronomers see large amounts of CO gas in a galaxy, they conclude that there also is a large amount of molecular Hydrogen present, and thus a large reservoir of fuel for star formation.

In the latest study, scientists painstakingly produced a physical model of the lensing intermediate galaxy. By knowing the mass, structure and orientation of this galaxy, they could then deduce the details of how it bends the light and radio waves from the more-distant galaxy. This allowed them to reconstruct a picture of the distant object. By doing this with multiple VLA images made at different radio frequencies, they were able to measure the motions of the gas in the distant galaxy.

"The lensing galaxy was, in effect, part of our telescope. By projecting backward through the lens, we determined the structure and dynamics of the galaxy behind it," said Fabian Walter of the Max-Planck Institute for Astronomy in Germany.

PSS J2322+1944 was first discovered by George Djorgovski of Caltech, using the digitized Palomar Observatory Sky Survey. Later radio and optical studies showed that it had a huge reservoir of dust and molecular gas, and indicated gravitational lensing.

Gravitational lenses were predicted, based on Albert Einstein's General Theory of Relativity, in 1919. Einstein himself showed in 1936 that a perfectly-aligned gravitational lens would produce a circular image, but felt that the chances of actually observing such an object were nearly zero. The first gravitational lens was discovered in 1979, and the first Einstein Ring was discovered by researchers using the VLA in 1987.

Riechers, Carilli, and Walter worked with Brendon Brewer and Geraint Lewis of the University of Sydney in Australia, Frank Bertoldi of the University of Bonn in Germany, and Pierre Cox of the Institute of Millimeter Radio Astronomy in France. The scientists reported their findings in the October 20 edition of the Astrophysical Journal.

Provided by National Radio Astronomy Observatory

Explore further: First potentially habitable Earth-sized planet confirmed: It may have liquid water

add to favorites email to friend print save as pdf

Related Stories

Image: Galactic serial killer

Apr 02, 2014

This new image from the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile shows two contrasting galaxies: NGC 1316, and its smaller neighbour NGC 1317. These two are quite close to each other ...

RX J1532.9+3021: Extreme power of black hole revealed

Jan 23, 2014

( —Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in ...

Radio galaxies in the distant universe

Jun 26, 2012

( -- 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 ...

Recommended for you

A sharp eye on Southern binary stars

7 hours ago

Unlike our sun, with its retinue of orbiting planets, many stars in the sky orbit around a second star. These binary stars, with orbital periods ranging from days to centuries, have long been the primary ...

Hubble image: A cross-section of the universe

8 hours ago

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range ...

Cosmologists weigh cosmic filaments and voids

11 hours ago

( —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

User comments : 0

More news stories

Cosmologists weigh cosmic filaments and voids

( —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Hubble image: A cross-section of the universe

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range ...

Hackathon team's GoogolPlex gives Siri extra powers

( —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...