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Discovery of “furthest object” said to pave way for probing early cosmos

April 28, 2009
World Science staff

An ex­plo­sion in space de­tected April 23 marks the most dis­tant, longest-a­go event and ob­ject known, as­tro­no­mers say.

Ob­jects seen fur­ther away in space al­so ap­pear as fur­ther back in time, since it takes time for their light to get he­re.

Gamma-ray bursts are pow­er­ful flashes of en­er­get­ic gamma-rays last­ing from less than a sec­ond to sev­er­al min­utes. They re­lease a tre­men­dous amount of en­er­gy in this short time mak­ing them the most pow­er­ful events in the Uni­verse. They are thought to be most­ly as­so­ci­at­ed with the ex­plo­sion of stars that col­lapse in­to black holes. In the ex­plo­sion, two je­ts of very fast-mov­ing ma­te­ri­al are ejected, as de­picted in this artist’s il­lus­tra­tion. If a jet hap­pens to be aimed at Earth, we see a brief flash. (Cour­te­sy ESO)

Al­though there have been a num­ber of such rec­ord-breakers in the past, as­tro­no­mers say each rec­ord paves the way for prob­ing ear­li­er and ear­li­er in­to the his­to­ry of the uni­verse, al­low­ing an un­prec­e­dent­ed un­der­stand­ing of its ev­o­lu­tion.

The blast ap­par­ently took place more than 13 bil­lion years ago, about 600 mil­lion years af­ter the es­ti­mat­ed birth of our uni­verse.

Gamma-ray bursts are pow­er­ful flashes of high-energy light, not vis­i­ble to the hu­man eye, last­ing from less than a sec­ond to sev­er­al min­utes. The most pow­er­ful blasts known, they’re thought to be mostly as­so­ci­at­ed with the death throes of stars col­laps­ing in­to black holes, ex­tremely com­pact ob­jects whose gra­vity sucks in eve­ry­thing near­by.

The new­found burst, des­ig­nat­ed GRB 090423, was de­tected by the Swift sat­el­lite, an in­stru­ment of NASA and two col­la­bo­rat­ing or­gan­iz­a­tions. The 10-sec­ond burst was seen in the di­rec­tion of the con­stel­la­tion Le­o, or the Li­on. It was soon be­ing fol­lowed by a range of ground-based tele­scopes watch­ing the af­termath of the ex­plo­sion. These in­clud­ed the Eu­ro­pe­an South­ern Ob­ser­va­to­ry’s Very Large Tel­e­scope at Paranal, Chil­e, whose ob­serva­t­ions led to the dis­tance es­ti­mate.

“The light com­ing from the ex­plo­sion has been stretched, or ‘red­shift­ed,’ con­sid­erably by the ex­pan­sion of the Uni­verse,” said Nial Tan­vir, lead­er of the team mak­ing the Very Large Tel­e­scope ob­serva­t­ions. 

The light waves from the burst are es­ti­mat­ed to have been stretched to 8.2 times their orig­i­nal length, a fac­tor that es­tab­lishes this as “most re­mote gamma-ray burst ev­er de­tected, and al­so the most dis­tant ob­ject ev­er dis­cov­ered—by some way.” 

The ex­plo­sion is estimated to have oc­curred when the cos­mos less than five per­cent of its cur­rent age. Astro­nom­ers think the first stars formed when the uni­verse was be­tween 200 and 400 mil­lion years old.

“This discovery proves the im­por­tance of gamma-ray bursts in prob­ing the most dis­tant parts of the Uni­verse,” said Tan­vir. “We can now be con­fi­dent that even more re­mote bursts will be found in the fu­ture, which will open a win­dow to stu­dy­ing the very first stars.” 

The pre­vi­ous rec­ord hold­er for most dis­tant ob­ject known was a gal­axy known as I0K-1, de­tected by Jap­a­nese re­search­ers in 2006 and seen as it was an es­ti­mat­ed 780 mil­lion years af­ter the birth of the uni­verse.

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An explosion in space detected last Thursday marks the most distant, longest-ago event and object known, astronomers say. Objects seen further away in space also appear as further back in time, since it takes time for their light to get here. Although there have been a number of such record-breakers in the past, astronomers say each record paves the way for probing earlier and earlier into the history of the universe, allowing an unprecedented understanding of its evolution. The blast apparently took place more than 13 billion years ago, about 600 million years after the estimated birth of our universe. Gamma-ray bursts are powerful flashes of high-energy light, not visible to the human eye, lasting from less than a second to several minutes. The most powerful blasts known, they’re thought to be mostly associated with the death throes of stars collapsing into black holes, extremely compact objects whose gravity sucks in everything nearby. The newfound burst, designated GRB 090423 was detected by the Swift satellite, an instrument of NASA and two collaborating organizations. The 10 second burst was seen in the direction of the Leo, or the Lion. It was soon being followed by a range of ground-based telescopes watching the aftermath of the explosion. These included the European Southern Observatory’s Very Large Telescope at Paranal, Chile, whose observations led to the distance estimate. “The light coming from the explosion has been stretched, or ‘redshifted,’ considerably by the expansion of the Universe,” said Nial Tanvir, leader of the team making the Very Large Telescope observations. The light waves from the burst are estimated to have been stretched to 8.2 times their original length, a factor that establishes this as “most remote gamma-ray burst ever detected, and also the most distant object ever discovered—by some way.” The explosion is believed to have occurred when the cosmos less than five percent of its current age. It is believed that the very first stars only formed when the Universe was between 200 and 400 million years old. “This discovery proves the importance of gamma-ray bursts in probing the most distant parts of the Universe,” said Tanvir. “We can now be confident that even more remote bursts will be found in the future, which will open a window to studying the very first stars.” The previous record holder for most distant object known was a galaxy known as I0K-1, detected by Japanese researchers in 2006 and seen as it looked an estimated 780 million years after the birth of the universe.