Disturbing the Universe

David L Clements, science and science fiction


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A new redshift record!

A new record for most distant object* seems to have been claimed for the gamma ray burst GRB_090423. The burst, a brief flash of gamma rays and associated afterglow, was first detected by the SWIFT satellite, and then ground based telescopes followed up these observations with imaging and, once the optical/near-IR counterpart was found, spectroscopy. In this case the object proved to be very red with essentially no emission in the optical. This is a clear indicator for high redshift. The surprise was just how high – a redshift of 8.1, corresponding to just 630 Million years after the Big Bang.

The burst will have now faded so the likelihood of seeing anything more from this particular spot on the sky is probably low, but these observations push back still further the point at which we know condensed objects to have formed. They’ll also have something to say about the reionization of the universe which should have been happening around the time this gamma ray burst went off.

All rather exciting!

As a further footnote I am impressed that the wikipedia page for GRB_090423 is already up containing clear links to all the GCN circulars on the object. An impressive example of rapid online publication.

* This means most distant collapsed object as opposed to the cosmic microwave background which is more distant, coming just about 100000 years after the Big Bang, but isn’t a collapsed object like a star or black hole since it comes from the opacity of the entire universe.

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