University of Leicester astronomers in discovery of 'most distant object ever seen'

Posted by pt91 at May 26, 2011 09:52 AM |
Researchers look back in time at exploding star spotted at edge of the galaxy
University of Leicester astronomers in discovery of 'most distant object ever seen'

Image of the site of the GRB. Credit: Gemini Observatory/ AURA/ Levan, Tanvir, Cucchiara

Issued by University of Leicester Press Office on 26 May 2011

Jpeg image available from pressoffice@le.ac.uk depicting location of exploding star

An international team of UK and US astronomers, including scientists from the University of Leicester’s  Department of Physics and Astronomy,  have spotted the most distant explosion, and possibly the most distant object, ever seen in the Universe.

The exploding star, known as a Gamma-ray Burst (GRB) was briefly as  bright as several thousand galaxies (more than a million million times the brightness of the sun), which allowed it to be detected at an estimated distance of 13.14 billion light years  - putting it 96% of the  way to the edge of our observable Universe.

The research is presented in a paper by an international team of astronomers, with major contributions from UK scientists at the   Universities of Leicester and Warwick. The research uses the Swift satellite, the   Gemini North Observatory and the Hubble Space Telescope and is accepted for publication in the Astrophysical Journal.

Dr Andrew Levan of the University of Warwick, one of the first people to observe the explosion and the second author of the paper, said:  “The race to find distant objects stems from the desire to find and study the first stars and galaxies that formed in the Universe, in the first few hundred million years after the Big Bang.

"By looking very far away, because the light takes so long on its journey to reach the Earth, 

Astronomers are effectively able to look back in time to this early era. Unfortunately, the immense  distances involved make this very challenging.

090429B_hst 300
Image of the site of the GRB. Credit: Gemini Observatory/ AURA/ Levan, Tanvir, Cucchiara

Observations with the Hubble Space Telescope show that the galaxy from which this gamma-ray burst originated is too faint for detection, even with the most powerful telescope ever built.

“This GRB shows us that there is a lot of action going on in the   Universe which we can't currently see," said Prof Nial Tanvir, the leader of the Hubble Space Telescope programme. "Our observations show us that even the Hubble Space Telescope is only seeing the tip of the iceberg in the distant Universe".

"Swift is capable of finding some GRBs at distances corresponding to when the first stars are predicted in the Universe", said Prof Paul O'Brien   a member of the Swift team at the University of Leicester, "but we are also currently designing   future space observatories, such as Lobster or Janus, which are tuned to finding many more."

The gamma-ray burst was first detected by NASA's Swift satellite in April 2009. The research team spent two years carrying out a careful examination of their data to see if the burst really was a  record-breaker.

Thanks to their extreme brightness, gamma-ray bursts can be detected by Swift and other satellite observatories even when they occur at distances of billions of light years. While the bursts themselves last for minutes at most, their fading "afterglow" light remains observable with large telescopes for days or even weeks. By performing a sophisticated analysis of this light, the research team were able to show that the burst most likely has a redshift (the means astronomers use to  measure distance) of approximately 9.4.  While there is some uncertainty due to the faintness of the source, this is significantly greater than the previous record holding GRB, which had a redshift of 8.2.

The research led by former Penn State graduate student Antonino Cucchiara, now at

Lawrence Berkeley National Laboratory in the US,  has been accepted for publication in the Astrophysical Journal in a paper entitled “Photometric Redshift of z ~ 9.4 for GRB 090429B. 2011”

Antonino Cucchiara, then a graduate student at Penn State University, woke up in the early morning hours to direct observations at the Gemini telescope on Mauna Kea, Hawaii , working with co-authors Andrew Levan  from the University of  Warwick  and Nial Tanvir from the University of Leicester  and thesis supervisor Derek Fox from Penn State.

Notes for editors:

The Swift satellite is a joint US/UK/Italian mission, launched   in 2004 which detects approximately 100 GRBs per year.  The UK contribution to the Swift mission is provided by the UK Space Agency.

The Gemini North Observatory: is one of the world's largest optical   telescopes, with a mirror 8m in diameter, which is situated at over 4000m near the   summit of the volcano Mauna Kea, on the Big Island of Hawaii.  It is an international observatory, partly funded by the STFC on behalf of UK astronomers.

The Hubble Space Telescope: is a joint NASA/ESA satellite which was  launched in 1990.

For further details please contact:

Nial Tanvir

nrt3@star.le.ac.uk

office: 0116 2231217

Paul O'Brien

pto@star.le.ac.uk

Office: 0116 252 5203

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