29 June 2011

The Ever-Changing Record

I smiled when I heard the news.  An international team of astronomers has just announced the discovery of the most distant quasar, the luminous core of a young and active galaxy situated a whopping 12.9 billion light-years away.  That means the light from this quasar, likely generated as matter falls into a supermassive black hole, started on its journey just 770 million years after the Big Bang. 

This image of the record-setting quasar, ULAS J1120+0641, was
created from images taken from surveys made by both the Sloan
 Digital Sky Survey and the United Kingdom Infrared Telescope Deep
Sky Survey. The quasar appears as a faint red dot close to the center.

I smiled because this headline has been regularly appearing in the news for nearly half a century, ever since Caltech astronomer Maarten Schmidt recognized the first quasar in 1963.  Known as 3C 273, from its listing in a catalog of radio sources, Schmidt's quasar was about 2 billion light-years distant: small potatoes now but a huge cosmic distance in its day.  

Over the years, the most-distant-quasar record has gotten replaced as often as a newborn's diapers.  But now the distances are so great that they present some problems: the light from this newfound quasar suggests that the quasar is being powered by a black hole about two billion times more massive than our Sun. How did such a gargantuan object grow so quickly in the early days of the universe? As team member Daniel Mortlock, of Imperial College London, notes, "It's like rolling a snowball down the hill, and suddenly you find that it's 20 feet across!" Theorists will surely be putting on their thinking caps to find a way.

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