Introduction to Extra-galactic Radio Sources

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Introduction to Extra-galactic Radio Sources
Apparent Superluminal motion

• Anupreeta More
• My sincere thanks to Dr. Saikia (NCRA, Pune)

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Contents

• Features of an Extra-galactic radio source
• Fanaroff-Riley Classification
• Apparent Superluminal motion its explanation
• Relativistic Beaming
• Summary

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Features of an Extragalactic Radio source
C
D
B
A

• A) Core mas B) Jets pc-kpc
• C) Hotspots kpc D) Lobes (lobe to
  lobe) 100 kpc

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Fanaroff-Riley Classification R dist.
between brightest regions total extent of
the source L(178 MHz) 2x1025 W/Hz/rad2
Class FRI Class FRII

• hotspot lobe dominated
• collimated, supersonic jets
• stronger total radio power
• associated with more isolated large galaxies

• jet dominated
• turbulent, subsonic jets
• weaker total radio power
• associated with large cD galaxies located in
  rich clusters

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FRI
FRII

• 3C272.1 3C47

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Images of FRI sources
3C465 3C83.1B
3C296 1.4 GHz 1.38 GHz
1.5GHz
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Images of FRII sources

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VLBI maps of 3C273

• A second look

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Explanation of apparent superluminal motion
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Relativistic Beaming
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• The ratio of observed flux of a relativistically
• moving blob approaching at an angle q to the
• one receding (q p) is given by,
• Fapp (1 b cos q) 3a
• Frec (1 b cos q)

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Summary

• 1. FRI FRII sources may be intrinsically
  different or have
• different host galaxy environments
• 2. Orientation effects and Relativistic Beaming
• - explain SL motion one-sided jets
  respectively
• - help in building unified models