BLACK HOLES The following images and text descriptions are taken from the Hubble Space telescope ( There are many resources on the web relating to black holes. Here are 2 other interesting links: A good introductory tutorial on GR and black holes: Joe Wolfe's web pages discussing the twin paradox and other aspects of special relativity – linked from the School of Physics web page.

PRESS RELEASE NO.: STScI-PR97-18 FIREWORKS NEAR A BLACK HOLE IN THE CORE OF SEYFERT GALAXY NGC 4151 The Space Telescope Imaging Spectrograph (STIS) simultaneously records, in unprecedented detail, the velocities of hundreds of gas knots streaming at hundreds of thousands of miles per hour from the nucleus of NGC 4151, thought to house a supermassive black hole. this is the first time the velocity structure in the heart of this object, or similar objects, has been mapped so vividly this close to its central black hole. The twin cones of gas emission are powered by the energy released from the supermassive black hole believed to reside at the heart of this Seyfert galaxy. The STIS data clearly show that the gas knots illuminated by one of these cones is rapidly moving towards us, while the gas knots illuminated by the other cone are rapidly receding. The images have been rotated to show the same orientation of NGC The figures show: WFPC2 (upper left) -- A Hubble Wide Field Planetary Camera 2 image of the oxygen emission (5007 Angstroms) from the gas at the heart of NGC Though the twin cone structure can be seen, the image does not provide any information about the motion of the oxygen gas. STIS OPTICAL (upper right) -- In this STIS spectral image of the oxygen gas, the velocities of the knots are determined by comparing the knots of gas in the stationary WFPC2 image to the horizontal location of the knots in the STIS image. STIS OPTICAL (lower right) -- In this false colour image the two emission lines of oxygen gas (the weaker one at 4959 Angstroms and the stronger one at 5007 Angstroms) are clearly visible. The horizontal line passing through the image is from the light generated by the powerful black hole at the centre of NGC STIS ULTRAVIOLET (lower left) -- This STIS spectral image shows the velocity distribution of the carbon emission from the gas in the core of NGC It requires more energy to make the carbon gas glow (CIV at 1549 Angstroms) than it does to ionise the oxygen gas seen in the other images. This means we expect that the carbon emitting gas is closer to the heart of the energy source.

PRESS RELEASE NO.: STScI-PR97-17 A COLLISION IN THE HEART OF A GALAXY The Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has uncovered a collision between two spiral galaxies in the heart of the peculiar galaxy called Arp 220. The collision has provided the spark for a burst of star formation. The NICMOS image captures bright knots of stars forming in the heart of Arp 220. The bright, crescent moon-shaped object is a remnant core of one of the colliding galaxies. The core is a cluster of 1 billion stars. The core's half-moon shape suggests that its bottom half is obscured by a disk of dust about 300 light-years across. This disk is embedded in the core and may be swirling around a black hole. The core of the other colliding galaxy is the bright round object to the left of the crescent moon-shaped object. Both cores are about 1,200 light-years apart and are orbiting each other. Arp 220, located 250 million light-years away in the constellation Serpens, is the 220th object in Halton Arp's Atlas of Peculiar Galaxies. The image was taken with three filters. The colors have been adjusted so that, in this infrared image, blue corresponds to shorter wavelengths, red to longer wavelengths. The image was taken April 5, 1997.

Cygnus X-1, a Galactic black hole Artists impression of the accretion disk Black hole

Baganoff, F. K. et al. Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre, Nature, 413, , (2001). Also see: Is there a huge black hole in the Milky Way?

Web site: Energy may escape from a black hole when it is in a strong magnetic field which exerts a braking effect. This artist's impression illustrates how the MCG system may look.

Schematic diagram illustrating the possible origins of the iron line in the spectrum of MCG

The XMM-Newton spectrum of MCG Two lines are present at 6.4 keV: the narrow blue line corresponds to X- rays coming from iron that is far away from the black hole, towards the outer parts of the accretion disc. The broad yellow line is the new mystery feature fully revealed by XMM-Newton.