Transcript 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.