IZW1 is one of five distant quasars studied by astronomer Lei Hao and her colleagues at Cornell in 2005. These astronomers described a type of infrared emission from these objects, thought to come from dust in the core of these quasars. This observation helped confirm the idea that there is a torus, or donut, of dust around the black holes at the cores of some quasars.

Astronomers believe that the most energetic objects known in the universe are AGNs, or ‘active galactic nuclei.’

The distant quasars, for example, are a type of AGN. Since the early 1980s, these objects have been believed to be powered by material falling onto supermassive black holes at the cores of young galaxies. As the matter falls in, it’s heated, producing high-energy x-rays. As astronomers have tried to explain their observations, they’ve also envisioned a disc of gas around the black hole, and a torus, or doughnut, of dust around that.

But, as always, astronomers have wanted confirmation of their ideas. Lei Hao is a Cornell University astronomer. She and her team recently described a type of infrared emission from dust in the vicinity of at least five quasars. This type of emission has been looked for but not found until now.

Lei Hao: But now, with these emissions, the thing that we can do is to see what composes the dust, is it any different than the interstellar dust in our own galaxy? And from the temperature you can see is it very far away from the black hole, or is it very close to the black hole?

In other words, Hao’s observation will enable astronomers to understand these objects better.

Thanks today to Research Corporation, a foundation for the advancement of science.

Our thanks to:
Lei Hao
Department of Astronomy
Cornell University
Ithaca, NY