The Greatest Explosions since the Big Bang:

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The Greatest Explosions since the Big Bang
Supernovae!
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Up for discussion

• Why are they so important?
• How do we find them?
• How do we classify them?
• What is it that explodes?
• Major discoveries using supernovae

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The importance of Supernovae

• Nucleosynthesis of chemical elements
• Star formation histories
• Chemical evolution
• Distance measurement
• Peculiar velocity studies
• Cosmological models
• The nature of Gamma Ray Bursts

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Can you spot the new SN?
Photographic Plates UKS 6.6ox6.6o Wide
Field Imagers MaCHO 45x45 Mosaic II
36x36 ESO WFI 34x33 OmegaCam 1ox1o
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Searching for Supernovae
Construct a Template
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Searching for Supernovae - 2
New Image with SN
Shifted to Template
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Searching for Supernovae - 3
Adjusted for Seeing and transparency
Subtracted
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Searching for Supernovae - 4
Red Image
Blue Image
Red Subtraction
Blue Subtraction
Red Template
Blue Template
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Searching for Supernovae - 5

• Cosmic Ray
• Rare to have coincident CRs in 2 images
• Asteroid
• Only if observing close to the ecliptic
• Generally not associated with a galaxy in the
  template
• Variable Star
• Associated with a star in the template
• Recurrent over many observations
• AGN
• Located in the centre of the galaxy

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How many supernovae do we find?
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And the winner is --- KAIT!

• 76cm telescope _at_ Lick
• Robotic telescope to search for SNe and monitor
  other events (e.g. GRBs/Novae)

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Classification
Type Ic
t 1 week
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SN Progenitors
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Type II, Type Ib, Type Ic Progenitors
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Type Ia Progenitors
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Its all good!
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Or is it?
(Type Ia)
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Type IIn
vs
Type II
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Type Ia
Type IIn
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SN 1997cy
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SN 1999E
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Confused?
Type Ic
Type Ia
Type II
Type IIn
core-collapse
Type Ib
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Supernova classification tree
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Nucleosynthesis
Type Ia (white dwarf binary)
Core-collapse (massive stars)
Ni, Co, Mn, Fe gt Fe
C, O, N gtFe
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Late-time spectra of SNe
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Light Curves of Supernovae
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Light Curves of Type Ia SNe
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Brighter SlowerFainter Faster
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Luminosity-Decline Rate Relation
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Template Fitting MCLS ?m15
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Template Fitting - Stretch
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Template Fitting - how good is it?

• But why does this work at all

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Measuring Distances with SNIa

• Have absolute magnitude of the SN through
  template fitting methods
• Have apparent brightness of the SN through
  photometry

DISTANCES accurate to 7
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What have we learned from Type Ia Supernovae?
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The Universe is Accelerating!

• SNe at high-Z are fainter than expected
• Acceleration started sometime in the last 10
  billion years

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The Universe is Accelerating!

• Best cosmological model
• ?M 0.28
• ?? 0.72

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What Does this Mean?

• The Mundane Astronomers have been fooled by
  supernovae into believing the Universe is
  accelerating. Perhaps supernovae were
  intrinsically fainter in the past and therefore
  look further away?

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Probably not )

• CMB data alone suggests a flat universe with ?gt0
• Any 2 of CMB/SN/LSS taken together indicate an
  accelerating Universe with a dark energy
  component of 70

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What Does this Mean?

• The Heretical General Relativity (though sacred
  in Physics) may be wrong. Since the observations
  are interpreted through the predictions of
  General Relativity, the conclusion that the
  Universe is accelerating may also be wrong -/

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What Does this Mean?

• The Exciting The Universe is being accelerated
  by some unknown type of energy that is spread
  throughout the cosmos!

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Where do we go from here?

• SNAP - SN acceleration probe
• 2000 SNe/year for 3 years
• Expansion history to 1

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What have we learned from core-collapse
Supernovae?
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Hypernovae long duration GRBs
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Summary

• Importance

VERY

• Nucleosynthesis of chemical elements
• Measuring Distances/Cosmology
• Understanding GRBs

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Summary

• Discovery

Thank goodness for computers!

• Initially by eye (I cant bear to think of it!)
• Now by fully automatic, robotic telescopes

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Summary

• Classification Progenitors

Very messy!

• Basically 2 types
• Type Ia explosion of a white dwarf binary
• Core-collapse explosion of a massive star

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Summary

• Science

Very EXCITING!

• Type Ia revealed the accelerating Universe and
  the existence of dark energy
• Core-collapse are associated with GRBs

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Who is next to explode?
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Best Candidate?

• Bright as a half moon but a point of light, not a
  disk
• Visible to the naked eye for many months
• Could be tomorrow, could be in 10,000 years.

Betelgeuse
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Or perhaps?
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Interested in Learning More?
http//astronomy.swin.edu.au/lgermany/