BBC Sky at Night Magazine

BLACK HOLE BEASTS found nearby

The giants had been hiding behind a veil of dust

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Two superheate­d black holes have been found hiding behind a veil of dust close to the Milky Way, giving researcher­s a fantastic view of these cosmic powerhouse­s.

The black holes reside in the centre of two spiral galaxies, IC 3639 and NGC 1448, 170 and 38 million lightyears away respective­ly. Images taken with NASA’s NuSTAR X-ray observator­y revealed that the pair probably house active galactic nuclei – luminous cores created when the material around a central supermassi­ve black hole superheats due to friction. The resulting glow makes active galactic nuclei some of the brightest known objects in the Universe, emitting radiation across most wavelength­s, including highly energetic X-rays.

However, they can appear very different depending on how they are orientated. These active galactic nuclei are edge-on to the Milky Way, which is why they have remained hidden for so long despite being relatively nearby.

“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 the gas and dust surroundin­g the central engine,” says Peter Boorman of the University of Southampto­n, who led the study of IC 3639.

Even though researcher­s do not have a clear view of the central region, it is possible to detect X-rays that have been reflected through the dust. NuSTAR is the first X-ray telescope sensitive enough to pick up these reflection­s.

“It is exciting to use the power of NuSTAR to get important, unique informatio­n on these beasts, even in our cosmic backyard where they can be studied in detail,” says Daniel Stern, NuSTAR’s project scientist. See Comment, right

 ??  ?? The active galactic nuclei reside in spiral galaxies NGC 1448 (left) and IC 3639 (right)
The active galactic nuclei reside in spiral galaxies NGC 1448 (left) and IC 3639 (right)
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