Space

September 19, 2012

NASA telescopes spy ultra-distant galaxy amidst cosmic ‘dark ages’

With the combined power of NASA’s Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, astronomers have spotted what could be the most distant galaxy ever seen.

ight from the young galaxy captured by the orbiting observatories first shone when our 13.7-billion-year-old universe was just 500 million years old.

The far-off galaxy existed within an important era when the universe began to transit from the so-called cosmic dark ages. During this period, the universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, remotest epochs of cosmic history.

“This galaxy is the most distant object we have ever observed with high confidence,” said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore and lead author of a new paper appearing in Nature. “Future work involving this galaxy, as well as others like it that we hope to find, will allow us to study the universe’s earliest objects and how the dark ages ended.”

Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA’s telescopes. In other words, the starlight snagged by Hubble and Spitzer left the galaxy when the universe was just 3.6 percent of its present age. Technically speaking, the galaxy has a redshift, or “z,” of 9.6. The term redshift refers to how much an object’s light has shifted into longer wavelengths as a result of the expansion of the universe. Astronomers use redshift to describe cosmic distances.

Unlike previous detections of galaxy candidates in this age range, which were only glimpsed in a single color, or waveband, this newfound galaxy has been seen in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today’s largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing. In this phenomenon, predicted by Albert Einstein a century ago, the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and the newfound galaxy magnified the newfound galaxy’s light, brightening the remote object some 15 times and bringing it into view.

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way’s mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the epoch of reionization, the event that signaled the demise of the universe’s dark ages. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, a state that the gas has remained in since that time.

“In essence, during the epoch of reionization, the lights came on in the universe,” said paper co-author Leonidas Moustakas, a research scientist at NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Hubble and Spitzer, NASA’s James Webb Telescope, which is scheduled for launch in 2018. The newly described distant galaxy likely will be a prime target.

 




All of this week's top headlines to your email every Friday.


 
 

 
nasa-astronaut

Astronaut Stephen Frick retires from NASA

Astronaut Stephen Frick has retired from NASA to accept a position in the private sector. Frick, who flew as both a shuttle pilot and commander, left the Agency July 13. Steve has been a great asset to the astronaut office and ...
 
 
NASA/JPL-CalTech/R. Hurt photograph

NASA’s Kepler mission discovers bigger, older cousin to Earth

NASA/JPL-CalTech/R. Hurt photograph This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of ...
 
 
NASA photograph by A. Gemignani

Launch, docking returns ISS crew to full strength

NASA photograph by A. Gemignani The Soyuz TMA-17M rocket launched from the Baikonur Cosmodrome in Kazakhstan July 22, 2015 carrying Expedition 44 Soyuz Commander Oleg Kononenko of the Russian Federal Space Agency (Roscosmos), F...
 

 
NASA/JHUAPL/SwRI photograph

NASA’s New Horizons team finds haze, flowing ice on Pluto

NASA/JHUAPL/SwRI photograph Pluto sends a breathtaking farewell to New Horizons. Backlit by the sun, Pluto’s atmosphere rings its silhouette like a luminous halo in this image taken by NASA’s New Horizons spacecraft around ...
 
 
NASA photograph

NASA satellite camera provides ‘EPIC’ view of Earth

NASA photograph Earth as seen on July 6, 2015, from a distance of one million miles by a NASA scientific camera aboard the Deep Space Climate Observatory spacecraft. A NASA camera on the Deep Space Climate Observatory (DSCOVR) ...
 
 
NASA/JHUAPL/SWRI photograph

NASA’s New Horizons discovers frozen plains in heart of Pluto’s ‘heart’

In the center left of Pluto’s vast heart-shaped feature – informally named “Tombaugh Regio” — lies a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>