A Tour of Faint Active Nuclei in Chandra Deep Field South

Narrator (April Hobart, CXC): A long-standing question in astrophysics is: how and when did supermassive black holes appear and grow in the early universe? New research using NASA's Chandra X-ray Observatory and the Sloan Digital Sky Survey — called the SDSS — suggests that an answer to this question lies with the intermittent way giant black holes may consume material in the first billion years after the Big Bang.

Astronomers have determined the Big Bang occurred about 13.8 billion years ago and have evidence from the SDSS that supermassive black holes with masses of about a billion times that of the sun existed by about 12.8 billion years ago. This implies that supermassive black holes grew rapidly in the first billion years after the Big Bang. Yet, scientists have struggled to find signs of these growing giant black holes.

To address this conundrum, an all-female team of researchers examined different theoretical models and tested them against optical data from the SDSS and X-ray data from Chandra. Their findings indicate that black hole feeding during this era may turn on abruptly and last for short periods of time, which means this growth may be difficult to spot.

The timing of such growth may be key. The authors' model suggests that 13 billion years ago, about one third of supermassive black holes may have been accreting enough matter to be detectable. Just 200 million years earlier — a veritable blip in cosmic time — the number of potentially detectable black holes is only about 3%. In order to test this idea further, the researchers suggest that surveys with Chandra and future X-ray telescope that look at larger areas of the sky in X-rays are necessary.