SCNC 2002 - Dark Matter: Masses in Space that Go Undetected

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References
Roberts, J. 2002. Does Dark Matter?. UK Dark Matter Collaboration. Department of Physics at Sheffield University. [Available:http://w ww.bbc.co.uk/science/space/deepspace/darkmatter/index.shtml]
Kneib, J.-P., Ellis, R. and Treu T. 2003. A Detailed Map of Dark Matter in a Galactic Cluster Reveals How Giant Cosmic Structures Formed. California Institute of Technology. [Available: http://pr.caltech.edu/media/Press_Releases/PR12 414.html]
Smith, N. 2003. The UK Dark Matter search at Boulby Mine. UK Dark Matter Collaboration. [Available: http://hepwww.rl.ac.uk/ukdmc/boulby/boulby.html]
Rees, M. and Natarajan, P. 2003. A Field Guide to the Invisible Universe. Discover. Vol.24 (12)42-9

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SCNC 2002 - Dark Matter: Masses in Space that Go Undetected

  1. 1. Neutrinos are ‘ghostly’ particles, which can only be detected using giant detectors with a heavy water basin, like this in Canada Existence of Dark Matter: Its Evidences <ul><li>Orbital Velocities </li></ul>Blue line shows the slow decrease in orbital velocity. (After J.-C. Cuillandre, 2003) <ul><li>The speed of stars orbiting around the centre of galaxy should be proportional to the mass contained – the less stars it has, the slower it gets. </li></ul><ul><li>However, galaxies are found to have a high orbital velocity at the edge – stars would be hurled out of the galaxy due to centripetal forces </li></ul><ul><li>So a cloud of invisible matter must surround the galaxy, holding the stars in place </li></ul>2. Gravitational Distortions <ul><li>Lensing Studies revealed that in large clusters of galaxies, lights are distorted due to a very large unaccounted mass </li></ul><ul><li>In 2003, scientists in CalTech, USA measured the distortion and calculated the mass required. </li></ul><ul><li>Blue regions indicate undetected mass, holding the galaxies together like glue </li></ul>Dark Matter Map, of galaxy cluster C10024+1654.(After Observatoire Midi-Pyrénées in France and Caltech.) What are Dark Matters anyway? Characteristics <ul><li>Neutrinos </li></ul><ul><li>Abundant and unreactive, these particles are found to have a slight mass which can account for some of the undetected matter. </li></ul><ul><li>Weakly Interactive Massive Particles (WIMPs) </li></ul><ul><li>These are hypothetical particles and have yet to be detected. </li></ul><ul><li>Massive Astronomical Compact Halo Objects </li></ul><ul><li>This group includes planets, asteroids, gas clouds and even black holes in the universe. They can be faintly detected when they bend the light of a star. </li></ul><ul><li>Not luminous </li></ul><ul><li> Cannot be detected by telescopes </li></ul><ul><li>Not atoms: Do not influence nuclear reactions </li></ul><ul><li> Big Bang theory predicted exact amount of atoms </li></ul><ul><li>Slow moving relative to speed of light (‘cold’) </li></ul><ul><li> Take little time to settle and form galaxy clusters </li></ul>Likely Candidates Efforts have been put to detect WIMPs using its unreactive nature – it should be able to pass through deep Earth, reaching detectors at 1100m deep, like this one in UK. References Roberts, J. 2002. Does Dark Matter?. UK Dark Matter Collaboration . Department of Physics at Sheffield University. [Available:http://w ww.bbc.co.uk/science/space/deepspace/darkmatter/index.shtml] Kneib, J.-P., Ellis, R. and Treu T. 2003. A Detailed Map of Dark Matter in a Galactic Cluster Reveals How Giant Cosmic Structures Formed . California Institute of Technology. [Available: http://pr.caltech.edu/media/Press_Releases/PR12 414.html] Smith, N. 2003. The UK Dark Matter search at Boulby Mine . UK Dark Matter Collaboration. [Available: http://hepwww.rl.ac.uk/ukdmc/boulby/boulby.html ] Rees, M. and Natarajan, P. 2003. A Field Guide to the Invisible Universe. Discover. Vol.24 (12)42-9. Dark Matter: Masses in Space that Go Undetected By Chiu Hon Chim (2002315825) Detecting Dark Matter
  2. 2. Blue line shows the slow decrease in orbital velocity. (After J.-C. Cuillandre, 2003)
  3. 3. Dark Matter Map, of galaxy cluster C10024+1654.(After Observatoire Midi-Pyrénées in France and Caltech.)
  4. 4. Efforts have been put to detect WIMPs using its unreactive nature – it should be able to pass through deep Earth, reaching detectors at 1100m deep, like this one in UK.
  5. 5. Neutrinos are ‘ghostly’ particles, which can only be detected using giant detectors with a heavy water basin, like this in Canada
  6. 6. <ul><li>Orbital Velocities </li></ul><ul><li>The speed of stars orbiting around the centre of galaxy should be proportional to the mass contained – the less stars it has, the slower it gets. </li></ul><ul><li>However, galaxies are found to have a high orbital velocity at the edge – stars would be hurled out of the galaxy due to centripetal forces </li></ul><ul><li>So a cloud of invisible matter must surround the galaxy, holding the stars in place </li></ul>
  7. 7. 2.Gravitational Distortions <ul><li>Lensing Studies revealed that in large clusters of galaxies, lights are distorted due to a very large unaccounted mass </li></ul><ul><li>In 2003, scientists in CalTech, USA measured the distortion and calculated the mass required. </li></ul><ul><li>Blue regions indicate undetected mass, holding the galaxies together like glue </li></ul>
  8. 8. Characteristics <ul><li>Not luminous </li></ul><ul><li> Cannot be detected by telescopes </li></ul><ul><li>Not atoms: Do not influence nuclear reactions </li></ul><ul><li> Big Bang theory predicted exact amount of atoms </li></ul><ul><li>Slow moving relative to speed of light (‘cold’) </li></ul><ul><li> Take little time to settle and form galaxy clusters </li></ul>
  9. 9. <ul><li>Neutrinos </li></ul><ul><li>Abundant and unreactive, these particles are found to have a slight mass which can account for some of the undetected matter. </li></ul><ul><li>Weakly Interactive Massive Particles (WIMPs) </li></ul><ul><li>These are hypothetical particles and have yet to be detected. </li></ul><ul><li>Massive Astronomical Compact Halo Objects </li></ul><ul><li>This group includes planets, asteroids, gas clouds and even black holes in the universe. They can be faintly detected when they bend the light of a star. </li></ul>Likely Candidates
  10. 10. References Roberts, J. 2002. Does Dark Matter?. UK Dark Matter Collaboration . Department of Physics at Sheffield University. [Available:http://w ww.bbc.co.uk/science/space/deepspace/darkmatter/index.shtml] Kneib, J.-P., Ellis, R. and Treu T. 2003. A Detailed Map of Dark Matter in a Galactic Cluster Reveals How Giant Cosmic Structures Formed . California Institute of Technology. [Available: http://pr.caltech.edu/media/Press_Releases/PR12 414.html] Smith, N. 2003. The UK Dark Matter search at Boulby Mine . UK Dark Matter Collaboration. [Available: http://hepwww.rl.ac.uk/ukdmc/boulby/boulby.html ] Rees, M. and Natarajan, P. 2003. A Field Guide to the Invisible Universe. Discover. Vol.24 (12)42-9.

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