Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. However, they give themselves away when material they feed on emits high-energy X-rays that NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission can detect.
Both of the black holes are the central engines of what astronomers call "active galactic nuclei," a class of extremely bright objects that includes quasars and blazars.
Depending on how these galactic nuclei are oriented and what sort of material surrounds them, they appear very different when examined with telescopes.
Active galactic nuclei are so bright because particles in the regions around the black hole get very hot and emit radiation across the full electromagnetic spectrum - from low-energy radio waves to high-energy X-rays.
Also Read
However, most active nuclei are believed to be surrounded by a doughnut-shaped region of thick gas and dust that obscures the central regions from certain lines of sight.
That means that instead of seeing the bright central regions, our telescopes primarily see the reflected X-rays from the doughnut-shaped obscuring material.
"Just as we can't see the Sun on a cloudy day, we can't directly see how bright these active galactic nuclei really are because of all of the gas and dust surrounding the central engine," said Peter Boorman, graduate student at University of Southampton in the UK, who led the study of an active galaxy called IC 3639, which is 170 million light years away.
The findings from NuSTAR confirm the nature of IC 3639 as an active galactic nucleus.
Annuar studied the spiral galaxy NGC 1448. The black hole in its centre was discovered in 2009, even though it is only 38 million light years away.
Researchers discovered that this galaxy also has a thick column of gas hiding the central black hole, which could be part of a doughnut-shaped region.
X-ray emission from NGC 1448 suggests for the first time that there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.
Disclaimer: No Business Standard Journalist was involved in creation of this content