What are quasars, really? (pulsars, stars, Sun, black hole)
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
If I forget the entire chapter that I read three times last night, and forget the Wiki article that I just read for the second time, and forget everything else I've read, will someone please explain what a quasar really is and really does? Every time I think I have it, I find a final statement saying "after the quasar finishes accreting the surrounding gas and dust, it becomes a galaxy.
Confusing because, before that, I'd read that quasars surround black holes in the center of galaxies. In other words, quasars are already inside galaxies.
So, a quasar will transform itself into a galaxy inside of a galaxy? Confusing. Elsewhere (and I cannot find it now) I'd read about quasars destroying galaxies.
If all this is already clarified on this forum, please point me to that. Or, please explain. Exactly what forms a quasar and then what does it do? Thank you.
Quasars , as we currently understand them , are basically primordial galaxies. Keep in mind they are very distant , with the nearest being the former quasar IC 2497 , at 730 million ly distant. Any images are viewed as they were in the past , so they have settled into stable galaxies by now. The term means 'quasi stellar radio source' due to the radio emissions given off by them. Regarding formation , they are ultraluminous galactic nuclei , powered by supermassive central black holes. My guess would be they may have began as clusters of massive 1st generation stars that left the main sequence and coalesced into one supermassive black hole before the cluster had time to disperse. The luminous region may be similar to the accretion disk around stellar mass black holes in close binaries , e.g. X ray binaries. I could be wrong , I remember reading about them in 1988 as a child. Look at the well known X ray source Cygnus X-1 , to give you an idea. I'm sure someone else will chime in to confirm or rebuke this , the input will be appreciated.
Quasars , as we currently understand them , are basically primordial galaxies. Keep in mind they are very distant , with the nearest being the former quasar IC 2497 , at 730 million ly distant. Any images are viewed as they were in the past , so they have settled into stable galaxies by now. The term means 'quasi stellar radio source' due to the radio emissions given off by them. Regarding formation , they are ultraluminous galactic nuclei , powered by supermassive central black holes. My guess would be they may have began as clusters of massive 1st generation stars that left the main sequence and coalesced into one supermassive black hole before the cluster had time to disperse. The luminous region may be similar to the accretion disk around stellar mass black holes in close binaries , e.g. X ray binaries. I could be wrong , I remember reading about them in 1988 as a child. Look at the well known X ray source Cygnus X-1 , to give you an idea. I'm sure someone else will chime in to confirm or rebuke this , the input will be appreciated.
So, do we have a black hole devouring an old galaxy while matter being tossed back preparing to form a new galaxy from which starts with those quasars? The black hole gives as well as gets? That would explain the newly forming galaxy seeming to be inside an old galaxy. If I understand the black hole right, it is at the center of the old galaxy.
Let's see if I can digest what you are saying. Meanwhile, I am remembering a couple of recent articles from Scientific American and Discover. I'll get those out and re-read them. Eventually, everything will fall into place.
If I forget the entire chapter that I read three times last night, and forget the Wiki article that I just read for the second time, and forget everything else I've read, will someone please explain what a quasar really is and really does? Every time I think I have it, I find a final statement saying "after the quasar finishes accreting the surrounding gas and dust, it becomes a galaxy.
Confusing because, before that, I'd read that quasars surround black holes in the center of galaxies. In other words, quasars are already inside galaxies.
So, a quasar will transform itself into a galaxy inside of a galaxy? Confusing. Elsewhere (and I cannot find it now) I'd read about quasars destroying galaxies.
If all this is already clarified on this forum, please point me to that. Or, please explain. Exactly what forms a quasar and then what does it do? Thank you.
Quasar is merely a contraction of "Quasi-Stellar" radio source. Astronomers did not have any idea what they were looking at when they first discovered quasars using radio telescopes. They looked "star-like" but were too far away to be stars, so they named them "Quasi-Stellar" radio source, which got shortened to quasar.
Quasars are really just very active, and very distant (redshift z > 0.5), galaxies. Nothing more. Quasars are not inside galaxies, they are galaxies with very active super-massive black holes. Quasars can indeed disrupt other nearby galaxies due to the jet of material exiting from both poles of their active super-massive black hole.
To make things even more confusing, astronomers have three different names for the exact same object, depending upon their point of view.
If they are looking at the galaxy with an active super-massive black hole from its side (< 45° angle), then it is a radio galaxy.
If they are looking at the galaxy with an active super-massive black hole from more than a 45° angle, but less than a 90° angle, then it is a quasar.
If they are looking at the galaxy with an active super-massive black hole from directly at one of its poles, then it is a blazar.
Astronomers are really good at naming things before they know what they are. Such as "quasars," "blazars," "pulsars," "planetary nebula" (which have nothing to do with planets), etc., etc.
Quasar is merely a contraction of "Quasi-Stellar" radio source. Astronomers did not have any idea what they were looking at when they first discovered quasars using radio telescopes. They looked "star-like" but were too far away to be stars, so they named them "Quasi-Stellar" radio source, which got shortened to quasar.
Quasars are really just very active, and very distant (redshift z > 0.5), galaxies. Nothing more. Quasars are not inside galaxies, they are galaxies with very active super-massive black holes. Quasars can indeed disrupt other nearby galaxies due to the jet of material exiting from both poles of their active super-massive black hole.
To make things even more confusing, astronomers have three different names for the exact same object, depending upon their point of view.
If they are looking at the galaxy with an active super-massive black hole from its side (< 45° angle), then it is a radio galaxy.
If they are looking at the galaxy with an active super-massive black hole from more than a 45° angle, but less than a 90° angle, then it is a quasar.
If they are looking at the galaxy with an active super-massive black hole from directly at one of its poles, then it is a blazar.
Astronomers are really good at naming things before they know what they are. Such as "quasars," "blazars," "pulsars," "planetary nebula" (which have nothing to do with planets), etc., etc.
AGN = Active Galactic Nuclei
I understand what you are saying but I'll have to dig out that one line from the book that seemed to be putting a quasar with its black hole inside another galaxy. I'll probably find I'm mis-reading but I'll look for it asap. I had something to do with the quasar's black hole "devouring" stars from an old galaxy.
I understand what you are saying but I'll have to dig out that one line from the book that seemed to be putting a quasar with its black hole inside another galaxy. I'll probably find I'm mis-reading but I'll look for it asap. I had something to do with the quasar's black hole "devouring" stars from an old galaxy.
Galactic collisions can create quasars. As the two galaxies collide the super-massive black hole from one, or the other, or both galaxies, would have new material to consume which could kick-start one or both galaxies to become a quasar.
If our own Milky Way galaxy's super-massive black hole were to suddenly start consuming lots of stars, then from a distant galaxy (redshift z > 0.5 away), depending on their angle of view, our galaxy would appear to them as a radio galaxy, a quasar, or a blazar.
Galactic collisions can create quasars. As the two galaxies collide the super-massive black hole from one, or the other, or both galaxies, would have new material to consume which could kick-start one or both galaxies to become a quasar.
If our own Milky Way galaxy's super-massive black hole were to suddenly start consuming lots of stars, then from a distant galaxy (redshift z > 0.5 away), depending on their angle of view, our galaxy would appear to them as a radio galaxy, a quasar, or a blazar.
Which takes me back to my original post where I quoted the sentence: "After the quasar finishes accreting the surrounding gas and dust, it becomes a galaxy. So, galaxies become quasars and then quasars become galaxies.
Which takes me back to my original post where I quoted the sentence: "After the quasar finishes accreting the surrounding gas and dust, it becomes a galaxy. So, galaxies become quasars and then quasars become galaxies.
See my dilemma?
I do indeed. Unfortunately, I can not clear up your confusion because both could be true.
A super-massive black hole that encounters a lot of material (gas, stars, etc.) could start consuming that material and after it has finished eating everything in its vicinity result in an elliptical galaxy.
Or, two galaxies may collide giving one or both super-massive black holes more material to consume, reigniting them.
So quasars could be an indication of a new galaxy in the process of being created. Or it could mean that two galaxies have collided with each other. The only thing that we know from our observations is that a super-massive black hole has a lot of material to consume, or it could not produce a radio galaxy/quasar/blazar. Everything after that is speculation.
I do indeed. Unfortunately, I can not clear up your confusion because both could be true.
A super-massive black hole that encounters a lot of material (gas, stars, etc.) could start consuming that material and after it has finished eating everything in its vicinity result in an elliptical galaxy.
Or, two galaxies may collide giving one or both super-massive black holes more material to consume, reigniting them.
So quasars could be an indication of a new galaxy in the process of being created. Or it could mean that two galaxies have collided with each other. The only thing that we know from our observations is that a super-massive black hole has a lot of material to consume, or it could not produce a radio galaxy/quasar/blazar. Everything after that is speculation.
Ah well. If either could be right, we have no problem. We only have to say it was "this or that". Right? I've run into this sort of statement once or twice before in "Origins". Now I know it isn't necessarily contradicting itself.
Ah well. If either could be right, we have no problem. We only have to say it was "this or that". Right? I've run into this sort of statement once or twice before in "Origins". Now I know it isn't necessarily contradicting itself.
Sort of a "it depends on what is is"?
Some call it "scientific inference," while others call it speculation. We see this extremely bright, energetic, and distant object and we try to make sense of what we are seeing.
Radio galaxies/quasars/blazers produce an enormous amount of energy. Only something that is several million or even several billion times the mass of our sun could produce such energy. We only know of one object that massive - super-massive black holes.
We know very little about super-massive black holes, other than they are found at the center of an overwhelming number of galaxies. We do not know how they originally formed.
They could have formed from stellar black holes that collided over billions of years; or
They could have formed from super-massive Population III type stars which formed ~30 million years to ~500 million years after the Big Bang; or
They could have formed during the Hadron Epoch (from 0.000001 seconds after the Big Bang to 1 second after the Big Bang) when the temperature and pressure of the universe was still high enough for black holes to form (a.k.a. primordial black holes), but long before stars were formed.
Or it could be any combination of the three, we just do not know one way or the other.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
