The Extreme Universe the search for Black Holes

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The Extreme Universe the search for Black Holes

• Dr. Tom Maccarone
• Dept Physics Astronomy
• Southampton University.

Preview Day 2009
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Structure of talk

• Basic ideas about Black Holes and how we search
  for them
• Astrophysics research at Southampton University
• Undergraduate astronomy programmes

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Escape Velocity
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Escape velocity formula

• For a particle to escape, kinetic energy must
  equal gravitational energy i.e.

½mv2 GmM/r
Where m mass of particle, M mass of
astronomical body, r size of astronomical body
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What is possible?
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Over 200 years of Black Holes
Thus a Black Hole is an object that is so dense
that the Escape Velocity Speed of light
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Supernovae

• Eventually though (after hundreds to thousands of
  millions of years) the star runs out of fuel
• We no longer have a balance and most stars (like
  our Sun) eventually collapse to become dwarf
  stars
• BUT, if our star is more than 8 times the mass of
  our Sun then it will not collapse quietly.
• It undergoes one last violent outburst, throwing
  off 90 of its material into space supernova!

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Limits of matter falling on to a Black Hole
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How we look for black holes

• Eddington limit is
• 1031 W per solar mass
• Bright X-ray sources black holes or neutron
  stars
• Neutron stars have a maximum mass of about 3
  solar masses
• Sources brighter than 3 x 1031 W probably black
  holes
• We usually can find black holes only if they are
  in binary star systems!

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The Milky Way
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The firstBlackHole foundin the MilkyWay
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Proving an object is a black hole

• Must measure the mass and show it is heavier than
  the maximum mass for a neutron star
• Use Kepler's Laws
• Measure velocity of star, mass of star, and
  inclination angle of orbit, then
• M(P) (V3 sin3i)/(2? G)?

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Centre of our Galaxy
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Andromeda
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How many Black Holes?

• In our galaxy there must be many millions of
  stellar-mass size black holes
• At the centre of every galaxy is probably a
  million to billion solar mass black hole
• There are probably 100 billion galaxies in the
  observable Universe.

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Research into astronomy at Southampton

• Research high energy astrophysics
  understanding the Extreme Universe (exceptionally
  hot and dense).
• Studies of black holes, neutron stars and white
  dwarfs in the Milky Way in other galaxies
• Testing General Relativity at its limits.

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INTEGRAL an ESA mission
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The INTEGRAL Galactic Plane Survey
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Teaching of astronomy

• BSc-with-Astronomy 3 year course
• MPhys-with-Astronomy 4 year course
• Both include a 6 month astronomy project in the
  Final Year
• Both include a Field Trip to Tenerife in the 2nd
  year

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Other major instrument projects at Southampton
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Final Year Projects
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Tenerife Field Trip

• Two weeks in Tenerife during the Easter vacation
  of your 2nd year
• First week working at University of La Laguna
  with Spanish students
• Second week at the Izana Observatory

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• MPhys Astrophysics with a Year Abroad
• First 2 years as per the normal MPhys programme
  (including the Tenerife Field Trip)?
• 4th year spent at the Center for Astrophysics,
  Harvard University doing research
• 2000 pound bursary for final year

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Conclusions

• We offer an exciting astronomy undergraduate
  programme
• Taught by international experts on the Extreme
  Universe
• Opportunities for your own research through
  Dissertations, Final Year projects and (if you
  wish) a year at Harvard.

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Questions?

• www.astro.soton.ac.uk