London:
Two monster black holes in the galaxies close to the solar system have been detected by the scientists, who used data from NASA telescopes for the study.
The supermassive black holes were discovered at the centre of the galaxies that are near to the Milky Way. The black holes were hiding behind mantles of gas and dust, hence were not spotted earlier.
Supermassive black holes at times go hiding behind gas and dust and hence remain unnoticed from the gaze of many telescopes.
However, when material they feed on produces high-energy X-rays, they give themselves away. NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) mission can detect those emissions.
Both the monster black holes are present at the central engines of “active galactic nuclei,” class of extremely bright objects that includes quasars and blazars, as defined by astronomers.
“These black holes are relatively close to the Milky Way, but they have remained hidden from us until now,” said Ady Annuar, graduate student at Durham University in the UK.
These galactic nuclei look very different when examined using telescopes depending upon how they are oriented and what kind of material surrounds them.
Active galactic nuclei are very bright as particles present in the regions around the black hole turn too hot and churns out radiation across the full the full electromagnetic spectrum - from low-energy radio waves to high-energy X-rays.However, it is believed that a doughnut-shaped region of thick gas and dust surrounds most of the active nuclei. That region obscures the regions from certain lines of sight.
NuSTAR recently studied the active galactic nuclei that appears to be oriented such that astronomers view them edge-on.
It clearly means that our telescopes primarily see the reflected X-rays from the doughnut-shaped obscuring material instead of seeing the bright central regions.
“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 NuStar data from this object was analysed by the reserachers, who compared them with previous studies from NASA’s Chandra X-Ray Observatory and the Japan-led Suzaku satellite.
The nature of IC 3639 is an active galactic nucleus, confirms the findings from NuSTAR.
The spiral galaxy NGC 1448 was examined by Annuar. In 2009, the black hole in its centre was found, though it is just 38 million light years away.
This galaxy is also home to a thick column of gas hiding the central black hole, which could be part of a doughnut-shaped region, discovered researchers.
For the first time, the X-ray emission from NGC 1448 suggests that there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.NGC 1448 has a large population of young (just 5 million year old) stars, suggesting that the galaxy produces new stars at the same time that its black hole feeds on gas and dust, researchers have found.
