Credit: Carnegie-Irvine Galaxy Survey/NASA/JPL-Caltech
Monsters Under the Bed
Buried deep within the dust are monsters: supermassive black holes. If we're fortunate, we can see where the dangers lie and study their outrageous behavior. They usually can be found at the centers of galaxies, and many are not shy, and reveal their presence through outpourings of radio, optical and X-ray radiation. But some are harder to see. For some reason, most, if not all, supermassive black holes are surrounded by enormous, thick, doughnut-shaped structures of dust and gas. This dust screen can effectively hide the supermassive black hole if we happen to view the black hole through it. For example, the supermassive black hole in NGC 1448, one of the brighter galaxies near the Milky Way, was unseen for years. An indication of the prescence of this supermassive black hole was only discovered 8 years ago through reprocessed infrared radiation produced near the black hole and detected by the Spitzer Space Telescope, which showed that the black hole actually produced more than one quarter of the galaxy's infrared radiation. Now, NASA's newest black hole finder, NuSTAR, has been able to directly detect X-rays from the black hole itself. NuSTAR can do this because it observes at very high X-ray energies that can pass unobscured through the thickest walls of dust. The image above show a composite of the NuSTAR image (in purple) superimposed on an optical image of NGC 1448. The purple-blue emission at the center of the galaxy shows the high energy X-rays arising from NGC 1448's supermassive black hole.
Published: January 23, 2017
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 30-Jan-2017 08:33:03 EST