PCS 181 Lecture Notes - Lecture 5: Accretion Disk, London Academy Of Music And Dramatic Art, Dominant Wavelength

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21 Mar 2013
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Class 9
Apparent size of Quasar = d = v t
After we correct for the distance to the quasar, we find that
QSO 3C273 was the size of a large star!
How could the energy of 100 to 1000 galaxies be produced by an object the size of a large star ?
How could this energy be produced from such a small volume?
Vr = C*delta lamda/ Lamdalab
V = Ho d
D = V/Ho
The mechanism of a Quasar
- Quasars are usually found in groups of galaxies.
- The quasars and the galaxies have similar redshifts
o Similar velocities
o Similar distances
o An association
- “Fuzz” around Quasars shows stellar absorption spectra
- Quasars are very luminous centers of distant, young galaxies.
- Quasar energy is radiated by matter swirling in an accretion disk around a supermassive
Black Hole.
Summary of Quasar Properties
- Small, compact, blue objects (x-rays are the dominant wavelength)
- Looks like faint stars in photographs
- X-ray emission
- Large redshifts such that UV spectral lines appear in visible portion of the spectrum
- Spectra are dominated by emission lines
Know the names of the three spectra and how they are generated for the test (refer to
the handout)
- Optical luminosities are 100 to 1000 times that of normal galaxies
- Many vary in intensity over days or weeks
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- Some quasars exhibit jets (optical or radio)
Test
30 multiple choice questions
5 of them require use calculators
Review from Bergmann’s lecture notes
Photon: burst of energy
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Document Summary

Apparent size of quasar = d = v t. After we correct for the distance to the quasar, we find that. Qso 3c273 was the size of a large star! Quasars are usually found in groups of galaxies. The quasars and the galaxies have similar redshifts: similar velocities, similar distances, an association. Quasars are very luminous centers of distant, young galaxies. Quasar energy is radiated by matter swirling in an accretion disk around a supermassive. Small, compact, blue objects (x-rays are the dominant wavelength) Large redshifts such that uv spectral lines appear in visible portion of the spectrum. Know the names of the three spectra and how they are generated for the test (refer to the handout) Optical luminosities are 100 to 1000 times that of normal galaxies. Many vary in intensity over days or weeks. Some quasars exhibit jets (optical or radio) This is dust and gas that occupy space between the stars.

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