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“Every large galaxy in the Universe is believed to host a supermassive black hole at their centre, millions of times the mass of our Sun,” says Boorman. “These systems can devour vast quantities of matter due to their extreme gravitational pull, making the black holes grow. The in-falling matter then emits radiation across the full electromagnetic spectrum. These growing supermassive black holes are called Active Galactic Nuclei (AGN).
“The emission can be absorbed by thick clouds of gas and dust covering the AGN,” Boorman continues. “As the level of obscuration increases, only the highest energy X-rays can escape to be observed by us. X-rays are absorbed by the atmosphere so I use data from X-ray satellites located above our atmosphere — such as NuSTAR, Suzaku and Swift — to detect high energy X-ray emission throughout the Universe.”
“The black hole I’ve been studying is so hidden, that it requires highly sensitive observations in the highest energy X-rays to classify it as obscured. Such sensitivities are only available now with the NuSTAR satellite [launched in June 2012] which is designed to create images of the high energy X-ray sky sharper than ever before,” he adds. “By modelling the X-ray emission of supermassive black holes, we get a glimpse of their growth rates, and learn about the amount and composition of material blanketing them. IC 3639 turns out to be glowing extremely bright due to emission from hot Iron atoms whose origin is not fully understood.”
“In broader terms, we also hope to determine the distribution of obscured AGN across the Universe, and figure out how these supermassive black holes have evolved and grown over billions of years,” Boorman concludes. “For this purpose, we will soon begin a large new survey of other nearby AGN with NuSTAR, and we can expect many more discoveries in the coming years.”
“These black holes are relatively close to the Milky Way, but they have remained hidden from us until now,” said Annuar. “They’re like monsters hiding under your bed.”
“Although X-ray astronomy was ‘born’ in the 1960’s, the field is still in its infancy in many respects,” he says. “NuSTAR is helping to change the picture of what we know about supermassive black holes, even in the local universe where many questions remain unanswered. It is really a privilege to be the first to peer into places in the universe where no one has been able to see before.”