Question by Misty: What is the definition of ‘quasar’ and are they in any way related to black holes?
seasky.org’s definiton:
Quasar
An unusually bright object found in the remote areas of the universe. Quasars release incredible amounts of energy and are among the oldest and farthest objects in the known universe. They may be the nuclei of ancient, active galaxies.
Wikipedia’s definiton:
A quasi-stellar radio source (quasar) is a very energetic and distant galaxy with an active galactic nucleus. Quasars were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies.
If I google quasar and then click image results (http://images.google.com/images?q=quasar&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&sourceid=ie7&rlz=1I7GGIT_en&um=1&ie=UTF-8&sa=N&hl=en&tab=wi) and tehn google black hole and click image results (http://images.google.com/images?q=black%20hole&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&sourceid=ie7&rlz=1I7GGIT_en&um=1&ie=UTF-8&sa=N&hl=en&tab=wi) some of the images look the same.
The two definitons, which are different in some ways if I understand them correctly have me confused, and so do the shared pictures for quasar and black hole, so can someone tell me the true definiton of quasar and how quasars are related to black holes?
Best answer:
Answer by DVOTA
There is a black hole at the center of the quasar. The quasar is the bright relativistic jets/accretion disk around the black hole.
Add your own answer in the comments!
Seasky.org is wrong, Quasars are peculiar to very young galaxies.
Quasars are a special type of supermassive galactic nucleus observed in some young galaxies and they emit vast amounts of energy at exotic wavelengths. These may be the result of a supermassive Black Hole (BH) consuming mass at a rate faster than it has the time and space to digest it (due to the extreme curvature of “c”) and some of the matter is spun out to the poles where it is energetically ejected into intergalactic space – it has nowhere else to go!
After the Quasar consumes the wayward matter in its neighborhood, the emissions cease and the Quasar shuts down. These kinds of emissions have been observed to occur very briefly in stellar sized BHs. BHs that emit energy are likely just examples of galactic indigestion.
Given their extremely large distances as testified by their large red-shift, quasars cannot be peculiar to very young galaxies, quite to the contrary. They are objects which strongly resemble the active compact nuclei of certain spirals galaxies emitting strongly in the IR, known as Seyfert galaxies. They contain hot and tenuous gazes resembling the solar corona, with velocities of the order of 1/2000km/s, without it being clear whether this corresponds to gas falling in, shot out, or rotating rapidly.
Because their brightness vary sometimes in a matter of hours, they are thought to be small. However given their distance they must be extremely luminous to appear as they do and given their smallness, one estimates that their surface luminosity maybe 10^10 greater than normal galaxies. They also radiate at the other end: many are great X-ray emitters. And all this, to say the truth, is not at all properly understood. They are not black holes, or rather, we haven’t the slightest hint that they are, but of course people who tend to see black holes everywhere will certainly tell you that there is a black hole at the centre of every quasar. As usual there is no real indication and in any case it cannot be very massive given the small size of the object. It is correct that they were first thought of as being point like, hence the ‘quasi star’ from which derives their name.