According to current theories, a dense cloud of gas feeds material into the disk surrounding a supermassive black hole during its period of early growth, which "cloaks" or hides much of the quasar's bright light from our view.
As the black hole consumes material and becomes more massive, the gas in the cloud is depleted, until the black hole and its bright disk are uncovered.
Supermassive black holes, which are millions to billions of times more massive than our Sun, typically grow by pulling in material from a disk of surrounding matter.
Rapid growth generates large amounts of radiation in a very small region around the black hole. Scientists call this extremely bright, compact source a "quasar."
"It's extraordinarily challenging to find quasars in this cloaked phase because so much of their radiation is absorbed and cannot be detected by current instruments," said Fabio Vito from the Pontificia Universidad Catolica de Chile who led the study.
"Thanks to Chandra and the ability of X-rays to pierce through the obscuring cloud, we think we've finally succeeded," Vito added.
The new finding came from observations of a quasar called PSO167-13, which was first discovered by Pan-STARRS, an optical-light telescope in Hawaii.