Download Lecture 31

A Perspective in Time: The History of Galaxies
Naked Quasars->Quasars->Active Galaxies->Present Galaxies
Dimmer-------------------------------->
Time------------------------>
NOTES:
Active Galactic Nuclei (AGN)
QUASARS: Radio Quasi-Stellar Objects. Maarten Schmidt
examined 3C273 (3C=Third Cambridge Catalog of Radio
sources) and found its distance from its redshift to be 2 billion
light years--not a star, and L = 1040 watts--1,000 L (MW)!!
.8 to 14(?) Billion years--distance range. L = 1038-1042 watts.
Energy comes from a region solar system-sized. Radio Jets.
A thermal (synchotron) and non-thermal (black-body)
continuous spectrum & broad (gas with varying speeds) lines.
Found to have stars around them (galaxies) in most cases.
Supermassive BH model suggests a billion solar masses by
Eddington Limit--Max M(BH) = L /30,000 (Solar Ms & Ls).
If larger mass, luminosity would blow away infalling material.
QSO's: Radio quiet Quasi-Stellar Objects.
ACTIVE GALAXIES: On average, seen at closer distances
than QSOs. Some in nearby clusters.
Seyfert Galaxies: ~1037 watts, 1,000x dimmer than QSOs.
Type I--broad (narrow peak) and narrow emission lines.
Type II--just narrow emission lines. ).
Radio Galaxies: Less luminous than Quasars. Often elliptical
or peculiar (collision-stimulated?).
3C273—first thought
To be a strange star.
Host galaxy—
blocking light
from core
First discovered Quasar
QUASARS: Quasi-Stellar Radio Objects. Maarten Schmidt
examined 3C273 (3C=Third Cambridge Catalog of Radio
sources) and found its distance from its redshift to be 2 billion
light years--not a star, and L = 1040 watts--1,000 L (MW)!!
Quasars are the dinosaurs of the cosmos. They went extinct
0.8 billion years ago, because we don’t see any closer than
0.8 billion light years.
Quasars: Distance: 8 to 14 Billion years. L = 1038-1042 watts.
Energy comes from a region solar system-sized. Radio Jets.
Found to have stars around them (galaxies) in most cases.
Quasars have a thermal (black body) and non-thermal
(synchotron) continuous spectrum & broad lines.
Broad vs Narrow lines: material moving in many directions
Or orbiting can produce a spread of Doppler Shifts.
Supermassive BH model of quasars suggests a billion solar
masses by Eddington Limit--Max M(BH) = L /30,000 (Solar Ms
& Ls). If larger, luminosity would blow away infalling material.
QSO's: Radio quiet Quasi-Stellar Objects.
Double QSO 0512-3329, 0.64 arcsec separation
Radio Loud vs radio quiet?
In terms of luminosity, Quasars (& QSOs) are the poppa bears,
Active Galaxies the momma bears, and Present Day Galaxies
like the Milky way are the baby bears. Successively about
1000x less luminous.
ACTIVE GALAXIES: On average, seen at closer distances
than QSOs. Some in nearby clusters.
Seyfert Galaxies: ~1037 watts, 1,000x dimmer than QSOs.
Type I--broad (narrow peak) and narrow emission lines.
Type II--just narrow emission lines. ).
Radio Galaxies: Less luminous than Quasars. Often elliptical
or peculiar (collision-stimulated?).
Radio Galaxy Centaurus A.
Collision of spiral with elliptical?
Blazars: variable quasarlike radio sources, with periods of years
--like galactic pulsars.
(Exs. BL Lacertae--3C279 Burst in 1937 and 1943—6 year period.)
Unified Model of
active galaxies:
AGN (Active
Galactic Nuclei).
In some cases, they
may be the same
thing seen from
different angles.
Naked Quasars: no stars around them
--NOT AGN.
White Hole? 7 discovered in 1995.