Friday, May 27, 2011

GRB 090429B: Farthest Detected Object in the Universe?

At approximately 10.2 billion light-years away from our solar system, JKCS 041 stunned the world as being the farthest known galaxy cluster in the entire universe in 2009. In fact, it was the farthest object until GRB 090429B and other candidates were discovered.

GRB 090429B was just like any other gamma-ray burst, exploding just like its companions until NASA's Swift satellite measured its distance away from our planet. Discovered on April 29th 2009, GRB (Gamma-Ray Burst) 090429B, had been a new candidate for position of being the farthest recorded object in the universe, farthest recorded from our planet, respectively. At the estimated distance of 13.14 billion light years (2.94 billion light years farther than JKCS 041), GRB 090429B has been the center of attention for a while, as published in a paper written by an international team of astronomers led by former Penn State University graduate student Antonino Cucchiara, now at the University of California, Berkeley.

Massive gamma-rays erupted from this exploding star (just like T Pyxidis from a previous article), when the universe was young. ScienceDaily, a trusted center for science research, but with an evolutionist worldview writes: "The gigantic burst...erupted...when the universe was less than 4% of its present age, just 520 million years old, and less than 10% of its present size." This leads into the great discussion of the 'Distant Starlight' problem, which you can read for yourself at the link above. 

But how and why does GRB 090429B explode? Gamma ray bursts are truly the brightest explosions known and are easily detected by the Swift satellite because of that fact. Swift can detect up to billions of light years on account of how bright and powerful the explosions are. Their real burst can last up to two minutes, but their fading 'afterglow' remains for days to months after the explosion. This was how the distance of GRB 090429B was measured; the 'afterglow' allows astronomers to measure the distance to the burst.

 But these 'afterglow' measurements can and will vary. In early 2009, GRB 090429B was at the estimated distance of 13.04 billion light-years. This record became surpassed in 2010 where GRB 090429B was recorded at 13.07 billion light-years away. Finally, it was recorded at 13.14 billion-light years away where it lies now. Antonio Cuccharia, when asked about the altering distances responded: "Our extreme estimate of the distance to GRB 090429B makes this a sort of 'revenge of the bursts. A gamma-ray burst is once more contending for the title of most distant object in the cosmos -- beyond the previously known most-distant quasars and galaxies."

After the distance was confirmed to be what it is now, headlines flew across the world because of how unique its properties were. Cucchiara and a few colleagues found that, while the afterglow was visible in infrared observations, it was not visible in optical light. This "drop out" behavior is a distinctive signature of distant objects, and has been used to identify similar objects. As time progressed as Cucchiara was viewing GRB 090429B, the 'afterglow' became dimmer and dimmer in the light of the visible spectrum as seen by humans.

"It was frustrating to lose sight of this burst, but the hints we had were so exciting there was no chance of us letting it go," Cucchiara tells us in 2009 about his trial with the gamma-ray burst. He spent two years (2010 and 2011) carefully observing it and actually included it with part of his doctoral thesis at Penn State. "Like the best politicians or talent-show contestants, the more we examined this burst, the better it looked," says Andrew Levan, the paper's second author.

However, is GRB 090429B the farthest object away from our planet? There are several requirements it must pass to make this fact true. First, it must lie beyond the 13.07 billion light year distance. Another galaxy reported in 2010 was this far, led by Matthew Lehnert and a team of astronomers at the Observatoire de Paris. According to a 98.9 percent probability, it is certain it is farther, but the odds could be off. Second, it must also lie beyond another galaxy reported in 2011 by a team of astronomers led by Rychard Bouwens of U.C. Santa Cruz. Either this is a complex or simple problem. The Bouwens team estimates that thier galaxy has a 20 percent chance that the galaxy isn't a record-breaker at all; but, if the galaxy is a record-breaker, it could range from a 13.11 to 13.28 billion light years. Only a 4.8% chance, if this were the case, could GRB 090429B be more distant than that. 'Overall, and treating these uncertainties as perfectly understood, there is a 23% chance that GRB 090429B is now the most distant known object in the Universe, the astronomers said,' ScienceDaily writes.

In the future, bright 'afterglows' like GRB 090429B could be used to explore the conditions of star and galaxy formation at these early cosmic epochs in detail. Derek Fox, an associate professor of astronomy and astrophysics at Penn State closes by telling us, "Discovering extremely distant bursts is pretty fun but we suspect there is a whole lot more information in the bursts, waiting for us that we have yet to access." The universe is still opening its secrets to us, and as we wait patiently, we could be able to obtain them. 

"The galaxy hosting the progenitor star of GRB 090429B was truly one of the first galaxies in the universe," Fox says. "Beyond the possible cosmic distance record, GRB 090429B illustrates how gamma-ray bursts can be used to reveal the locations of massive stars in the early universe and to track the processes of early galaxy and star formation that eventually led to the galaxy-rich cosmos we see around us today."

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