X-ray universe

Print edition : October 16, 2015

Figure 1: Rings of X-ray light centered on V404 Cygni, a binary system containing an erupting black hole (dot at center), were imaged by the X-ray telescope aboard NASA's Swift satellite from June 30 to July 4, following the detection of the X-ray outburst on June 15. Color indicates the energy of the X-rays, with red representing the lowest (0.800-1.5 kilo electron volts, keV), green for medium (1.5 keV-2.500 keV), and the most energetic (2.5- 5.0 keV) shown in blue. For comparison, visible light has energies ranging from about 2 to 3 eV. The dark lines running diagonally are artifacts of the imaging system. Photo: Andrew Beardmore (University of Leicester) and NASA/Swift

Figure 2: An artist’s impression of a black hole feasting on matter from its companion star in a binary system. Material flows from the star towards the black hole and gathers in a disc, where it is heated up, shining brightly at optical, ultraviolet and X-ray wavelengths before spiralling into the black hole. Part of the disc material does not end up onto the black hole but is ejected in the form of two powerful jets of particles. Photo: European Space Agency (ESA)/ATG medialab

Figure 4: X-rays span from a wavelength of about 0.008 nm (about 150keV) in the electromagnetic spectrum and extend across by four orders of magnitude to about 8 nm (about 0.15 keV), over which the earth's atmosphere is opaque. Photo: Wikipedia

Figure 5. X-ray telescopes and the electromagnetic spectrum. Photo: NASA

Astrosat is the latest instance of the revolution in X-ray astronomy, which, by mapping high-energy phenomena, gives us vital clues about the dynamics of the universe’s evolution.
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