October General Meeting Report
“Pulsar and Supernova Remnants”
Dr. Andrew Melatos, Melbourne University.
A sure sign that you are getting old is when the new crop of post-graduates start to look like highschool kids to you . Andrew Melatos for me testifies to that. I had to look up his Curriculum Vitae on the web to confirm he has completed his BSc (with honours) in Sydney in 1991, his PhD in 1995, became Research Fellow in Theoretical Astrophysics at Caltech in 1997 and Miller Fellow (Astronomy) at Berkeley USA from 1997-2000. He is currently Lecturer in the School of Physics at Melbourne University.
Andrew gave us a quick hop-skip and jump through the physics of supernovae and their left-over remnants, the Neutron Stars. There are now some 1500 of these exotic Pulsars or X-ray powerhouses known to astronomers. First found through their periodic “lighthouse” beams, these Pulsars have become a new field of physics unlike any other that can be studied on Earth. Magnetic fields a trillion times that on Earth, super-fluid vortexes, pulsar winds and gamma-ray bursts with energy equivalents of a million galaxies. Attempts to make sense of these mysteries challenge our understanding of physics, and for Andrew have been grouped into three categories in astrophysics, Pulsar Glitches, Relativistic Wind and Gamma Ray Bursts. In a fascinating PowerPoint presentation he showed dynamic rings, knots, wisps and jets of matter and antimatter around the pulsar in the Crab Nebula as observed in X-ray light by the Chandra satellite, changing in time between November 2000 and April 2001. It is speculated a high-speed wind of matter and antimatter particles from the pulsar plows into the surrounding nebula, creating a shock wave and forming the inner ring. Energetic shocked particles then move outward to brighten the outer ring and produce an extended X-ray glow. Furthermore, the discovery of the Hulse-Taylor binary pulsar, PSR B1913+16, along with more than two decades of pulsar timing measurements, has lead to spectacular confirmation of the emission of gravitational radiation by tight binary star systems.
Huge investments in a new generation of gravitational wave detectors, “LIGO” and the even more futuristic space-based “LISA”, are confirmation of our determination in trying to understand the mechanics at work under these extreme conditions. Both detectors use laser beam wave analysis to measure distance changes due to the movement of gravity waves. The LIGO, with terrestrial limitations, is theoretically capable to measure movements down to the width of an atom, and the LISA, free from mechanical interference, promises to give a 100fold increase in sensitivity.
How we on Earth are vulnerable to the threat of damaging radiation from almost anywhere in our Galaxy was graphically demonstrated by Lockie Cresswell in the closing vote of thanks to Dr Andrew Melatos