Distant Galaxies

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Distant Galaxies
Edwin Hubble Measured distances to
galaxies Combined that with galaxy velocities
Came up with the Hubble Diagram
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Vel. km/s
Velocity is proportional to distance v Ho d
Hubbles Law Ho slope Hubble Constant
Distance (Mpc - Megaparsecs)
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• Importance of Hubbles Law
• Used to determine distances (d) (need velocity
  of a galaxy and the value of Ho)
• What is Ho?
• 70 km/s/Mpc.
• 2. Why does the law exist?
• The law exists because the Universe is Expanding!
• 3. What does Ho measure?
• Time
• Hubbles Law can be used to study distant,
  younger galaxies and tells us how the Universe
  has/is evolving

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Active Galaxies
Galaxies that are far away are younger
galaxies. Younger galaxies ? unsettled
galaxies Active Galaxies Large Energy
outputs Energy/Light given off at extreme
wavelengths Variable energy output Active
Galactic Nuclei Active galaxies - often younger
galaxies
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• BL Lacs Blazars
• Characteristics
• No spectra features
• Non-thermal light
• Seyferts Type I and II
• Characteristics
• Bright, variable core
• Unusual spectra
• Unusual energy output x-ray, IR, UV
• High energy output

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Seyfert
Normal Galaxy
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Radio Galaxies
Many galaxies produce radio light Galaxies that
produce A LOT of radio light Radio Galaxy Types
of radio galaxy sources - From the core From
external lobes (large structures)
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Quasars
Quasi-stellar objects (QSO) - Quasars Look like
stars (points) Unusual spectra - emission lines
of ??? 1963 Maarten Schmidt What if the
unidentified features were actual common
features? Spectra is unusual because of a high
redshift - high velocity away
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Quasars - high redshift spectra ? high
velocities Hubbles law high velocity ? great
distance Quasar are amongst the most distant
objects observed! Characteristics High
Velocity Great distance implied (by Hubbles
law) Not very faint ? very luminous Small
energy source Emission lines in spectra, often
broad
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Model for Active Galaxies
BL Lac, Seyferts (I and II), Radio Galaxies,
Quasars All different? Or all the same? Could a
single model explain all of the features observed
in these active galaxies? What would be in this
model?
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Black hole in center Accretion disk around
it High velocity clouds Low velocity clouds Dusty
torus (donut) Jets
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Gravitational Lensing
Einsteins General Relativity on a cosmic scale
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