Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter

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Quasars and Low Surface Brightness Galaxies as
Probes of Dark Matter
Erik Zackrisson
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Outline

• Dark matter
• Dark matter halos
• Baryonic and non-baryonic dark matter
• Cold dark matter
• Quasars
• Gravitational lensing
• Redshift
• Low Surface Brightness Galaxies
• Rotation curves
• Summary of Results

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Dark Matter
Dark matter
Luminous matter
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First detection of dark matter

• Fritz Zwicky (1933) Dark matter in the Coma
  Cluster

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The Dark Matter Problem
2 (Luminous)
98 (Dark)
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Dark Matter Halos I
Galaxy ? Stars Gas Dust Supermassive Black
Hole Dark Matter
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Dark Matter Halos II
Luminous galaxy
Dark halo
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Baryonic Non-Baryonic Dark Matter

• Baryonic matter 15
• Example Stars, gas clouds, planets
• Missing 35
• Non-baryonic matter 85
• Example Axions, neutralinos,
• primordial black holes
• Missing 100
• Best model Cold Dark Matter (CDM)

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Cold dark matter and the evolution of structure
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Cold dark matter and the evolution of structure
II
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Cold Dark Matter Halos
Central density cusp predicted by cold dark
matter
R
Observed
Density
R
Dark matter halo
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Quasars
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(No Transcript)
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Gravitational lensing
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Gravitational lensing II
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Microlensing Made Simple
Obs! Fel bild!
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Microlensing Made Simple II
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Claim The long-term optical variability of
quasars is quased by microlensing
Hawkins, M.R.S. (1993, 1996, 1997, 2000, 2001,
2002, 2003)
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The dark matter puzzle solved?

• Mcompact ?10-3 Msolar
• Almost all of the dark matter in this form
• Primordial black holes?

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Expansion of the Universe
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Redshifts
High z ? Large distance Low z ? Small distance
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Claims of non-cosmological redshifts
z1
z2
Low-z galaxy with pairs of high-z quasars (with
z1?z2) aligned along minor axis
Low-z galaxy surrounded by overdensity of high-z
quasars
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Ejection scenarios
?
?
?
New galaxy (?), very low redshift (z1)
?
?
Bright quasar, low redshift (gtz1)
Faint quasar, high redshift (gtgtz1)
Local galaxy, very low redshift (z1)
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Low Surface Brightness Galaxies
Examples of Target Galaxies
The Very Large Telescope
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The Central Mass Budget
Low Surface Brightness Galaxies
High Surface Brightness Galaxies
Dark matter
Luminous matter
Dark matter
Luminous matter
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Rotation Curves
CDM prediction
Vrot
Density
Observed
Radius
Radius
Spectroscopy ? Rotation Curve ? Density
Profile
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Results

• Paper I
• Uncertainties in the typical quasar size ? Quasar
  variability cannot easily be used to constrain
  dark matter at the current time
• Paper II
• Microlensing cannot explain the long-term optical
  variability of quasars Hawkins is wrong!
• Paper III
• Non-cosmological redshift scenarios involving
  quasar ejection can be tested with observations
  of quasar host galaxies made a small telescope

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Results II

• Paper IV
• The bluest low surface brightness galaxies can be
  used to test hierarchical galaxy formation models
  provided that we can derive their ages
• The star formation rate of the bluest low surface
  brightness galaxies cannot have been constant or
  increasing unless the stellar initial mass
  function is unusual
• Paper V
• The density profiles of the dark halos
  surrounding the bluest low surface brightness
  galaxies are in conflict with the Cold Dark
  Matter predictions

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Errata

• Spikblad Polhemssalen ? Polhemsalen
• Page v optical long-term ? long-term optical
• Page 3 as the ray crossed ? as its ray grazed
• Page 24 (twice) reflectance ? reflection
• Page 33 z ? 23 ? z ? 24
• Page 35 the latter variations ? these variations
• Page 35 hoever are ? are however
• Page 37 by fast rise ? by a fast rise
• Page 44 10121014 m ? 10123?1013 m
• Page 56 disk by ? disk is given by
• Page 69 ett par procent ? några få procent
• Page 69 välkända astronomiska objekt ? välkända
  typer av astronomiska objekt
• Page 69 både vår och andra ? både vår egen och
  andra
• Paper I, page 26, column 2, paragraph 1 higher
  angular size distance ? higher light travel time
  distance
• Paper V, page 8 Division line should not be
  dashed