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Active Galaxies – 11c

Active Galaxies – 11c. A few galaxies that are far more luminous than any spiral or elliptical. Luminosities may exceed 1000 times that of the Milky Way. Emit more long wavelength radiation. Active Galaxies. 2 Types: Seyfert Galaxies Radio Galaxies Also there are Quasars.

deirdre-wilson
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Active Galaxies – 11c

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  1. Active Galaxies – 11c • A few galaxies that are far more luminous than any spiral or elliptical. • Luminosities may exceed 1000 times that of the Milky Way. • Emit more long wavelength radiation.

  2. Active Galaxies 2 Types: Seyfert Galaxies Radio Galaxies Also there are Quasars

  3. Seyfert Galaxies Nearly all of the energy emitted is in the radio and infrared from a central region called the galactic nucleus. This galactic nucleus can be 10 times brighter than the entire Milky Way galaxy!

  4. Radio Galaxies (Core-Halo and Lobe) Nearly all of the energy emitted is in the radio portion of the electromagnetic spectrum. Core-Halo Type - Radio emissions with similar luminosity to that of a Seyfert galaxy. Most of the energy comes from a central core.

  5. Radio Galaxies Lobe Type- Radio emissions with similar luminosity to that of a Seyfert galaxy. Most of the emissions are from huge extended regions called radio lobes.

  6. Radio Galaxies Emissions from radio galaxies shown in the (a) visible, and (b) radio portions of the electromagnetic spectrum.

  7. Radio Galaxies Core-Halo and Lobe type galaxies may differ only in their view from Earth

  8. Radio Galaxies This close-up of active galaxy M87 shows the galaxy jet imaged in the radio, infrared, and X-ray portions of the electromagnetic spectrum. Hubble Space Telescope witnesses spectacular flaring in extragalactic jet from M87's black hole

  9. Active Galaxies - Luminosity Most active galaxies exhibit a luminosity that changes over time. This Seyfert galaxy, called 3C 84, shows irregular intensity variations over time.

  10. Active Galaxies have • high luminosities • energy emission is non-stellar (too luminous) • output can be variable over time • often exhibit jets • broad emission lines indicating rapid internal motion What model could explain all of this?

  11. A massive black hole - having the mass of a million suns - may be responsible for the energy production in the center of the Milky Way. A Super Massive Black Hole - having the mass of a billion suns - may be responsible for the energy production in the center of an active galaxy. This is called a central engine.

  12. The Central Engine Infalling gas in an active galaxy forms an accretion disk and spirals down toward the black hole. The gas is heated to high temperatures by friction in the disk and emits large amounts of radiation.

  13. The Central Engine Accretion is around 20% efficient at converting mass into energy. Calculations show that only one solar mass every 10 years could result in the energy emission seen in the most luminous active galaxies. (1038 Watts) Accretion disks are comparable in size to our solar system

  14. The Central Engine “Active Galaxies”

  15. Active Galaxy Energy Emission The energy emission from an active galaxy in non-thermal. It does not match blackbody radiation curves. [Q]: What could cause this emission trend? [A]: Synchrotron radiation - electrons spiralling around a magnetic field.

  16. QUASAR - A Quasi-Stellar object (A star-like object) • In the 1960’s, faint radio sources with unfamiliar spectra were found. • In 1963, it was discovered that these unfamiliar spectra were actually Hydrogen lines redshifted by an ENORMOUS amount. • Redshifts corresponding to velocities of over 100,000 km/s (1/3 the speed of light) have been found. • Luminosities can be over 100 times that of an active galaxy (1040 Watts) Quasars are often known today as QSOs. Quasars are fueled by interactions that bring an inflow of gas to the black holes in the centers of galaxies. Asgas isfunneled into a galaxy's center, it feeds the supermassive black hole. However, it is the accretion onto the black hole that is the source of the quasar's energy.The telltale sign is an unusually large amount of infrared radiation due to the black hole’s heating of surrounding dust. Also, the doughnut-shaped structures that comprise the ancient black holes and dust clouds typically emit x-rays as the black hole cores devour their dusty rings.

  17. Although Quasars are the most luminous objects known in the universe, they often appear as unimpressive features due to their large distance. At the core of the galaxy below lies a quasar, an extremely powerful source of radiation as bright as trillions of suns that originates from the superheated gas of a black hole's accretion disk.

  18. Optical spectrum of Quasar 3C 273 shows a jet of material extending approximately 100,000 ly from the quasar.

  19. Optical spectrum of Quasar 3C 273. The width of the red-shifted spectra indicates rapid rotation.

  20. Scale drawing of the Milky Way galaxy. Quasar 3C 175. Red shift data indicates that this quasar is over 10,000,000,000 ly (10 billion ly) away! The lobes themselves extend 1,000,000 ly across!

  21. Sloan Digital Sky Survey (SDSS) telescope. Researchers at Princeton were operating this telescope remotely. It is located in Southern New Mexico. Quasar Red shift data indicates that the distance to this quasar is close to 14,000,000,000 ly! Quasars-supermassive black holes Quasar Cluster

  22. Below are pictures of Quasar PKS 1127-145. Visible light photograph.(Hubble) X-ray photograph (same field).(Chandra)

  23. Galaxy NGC 4319, and Quasar Markarian 205. Some astronomers originally hypothesizes that the two were part of a single system, but now realize that they are billions of light years apart.

  24. Energy Source for Quasars Quasars have many of the same properties of Active Galaxies: Non-thermal radiation Brightness that changes over time (irregularly) Jets that extend away from a central luminous region. [Q]: What explanation could explain these features? [A]: A super (duper?) massive black hole having the mass of a billion solar masses.

  25. Energy Source for Quasars [Q]: O.K. We have already used the billion solar mass model thing to explain the central engine of an active galaxy. Quasars are 100 times more luminous. How are they different? [A]: While the black hole in the central engine of an active galaxy may consume one star every ten years, a Quasar must consume 10 stars per year. The brightest Quasars may consume 1000 stars per year!

  26. A Binary Quasar? This image in 1979 appeared to be an unimaginable object. A binary Quasar. The upper left and lower right objects had identical properties. [Q]: If it is not a binary Quasar, then what could cause one object to appear to be in two places at one time? [A]: Gravitational lensing by a galaxy in the path of the light from the Quasar.

  27. A Binary Quasar? NO

  28. More Gravitational Lensing

  29. Active Galaxy Evolution - An idea

  30. Active Galaxy Evolution - An idea Show “Quasar Birth” Each of the Quasars in these Hubble photos appear to be in very small, young galaxies. This indicates that Quasars may be present during an early stage of galaxy evolution.

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