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Author Topic: Where is our local quasar remnant?  (Read 3944 times)

Offline LeeE

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Where is our local quasar remnant?
« on: 30/10/2009 17:13:48 »
If we accept that the universe is fundamentally the same everywhere, then an observer in the regions where we now see quasars should, when looking towards us, see quasars somewhere in our region of space.  Because such an observer will be seeing our past, just as we see theirs, we shouldn't expect to see an active quasar in our region of space, but we should see the remnants of one, or perhaps a few, quasars fairly close to us.

Does anyone know of any candidates for such quasar remnants nearby?

Incidentally, the current model for quasars involves material falling into very large Black Holes (wikipedia says):

"there is now a scientific consensus that a quasar is a compact region 10-10,000 times the Schwarzschild radius of the central supermassive black hole of a galaxy, powered by its accretion disc."

and also:

"Large central masses (106 to 109 Solar masses) have been measured in quasars using 'reverberation mapping'."

Now even if a quasar has quietened down over the billions of years since it was active, the region of space around it should still be brighter than the CMBR, and remember too that this isn't a tiny thing we're looking for here, but something that's pretty big, mass-wise.  Also, don't forget that the larger a Black Hole is, the colder it is and therefore the more slowly it will evaporate due to Hawking radiation, so these super-massive galactic mass Black Holes should still be around.


 

Offline Soul Surfer

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Where is our local quasar remnant?
« Reply #1 on: 30/10/2009 18:19:13 »
The closest Quasar remenant is probably the quiet black hole at the centre of our own galaxy although it was probably not a very powerful one because it is omy measured in millions and not billions of solar masses.
 

Offline LeeE

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Where is our local quasar remnant?
« Reply #2 on: 30/10/2009 18:53:53 »
The closest Quasar remenant is probably the quiet black hole at the centre of our own galaxy although it was probably not a very powerful one because it is omy measured in millions and not billions of solar masses.

Thanks for your thoughts, but wouldn't that suggest that every galaxy was once a quasar?  And how would active galaxies fit in with this?  The existence of active galaxies now, or at least relatively recently, would seem to suggest that they become, or continue to be, active after the quasar phase.  With active galaxies I believe we can still see most of the ejected material, so why can't we see the material ejected in the quasar phase?
 

Offline Vern

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Where is our local quasar remnant?
« Reply #3 on: 30/10/2009 19:07:32 »
I have a mind set for galactic ejected material, and pay attention to mention of it. I don't remember seeing anywhere that we can see most of galactic ejected material. Wouldn't most of this ejecta be ions and radiation?

Edit: I know that we can see material ejected from supernova type eruptions, but I'm looking for mention of material ejected outside of galaxies. I remember Halton Arp suggested that some Quasars seem to leave a trail of material from galaxies that appear much less red shifted than the Quasar.

The reason I pay attention to mention of galactic ejecta is a suspicion that it may be a candidate for the cause of galactic rotation anomaly.
« Last Edit: 30/10/2009 19:16:39 by Vern »
 

Offline LeeE

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Where is our local quasar remnant?
« Reply #4 on: 30/10/2009 19:16:58 »
Active galaxy jets are apparently mostly plasma, being partially ionised gas.  There's certainly material to be seen in them, and material that has to go somewhere.
 

Offline Vern

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Where is our local quasar remnant?
« Reply #5 on: 30/10/2009 19:22:35 »
I wondered whether we see most of the galactic ejecta. I know we see some of it, but I would guess we only see a small percentage.

I tend to suspect that Quasars more likely happen at the end of galactic existence rather than the beginning.
« Last Edit: 30/10/2009 19:25:52 by Vern »
 

Offline Vern

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Where is our local quasar remnant?
« Reply #6 on: 31/10/2009 12:30:51 »
This Wiki is a good article on Quasars. It indicates that we have observed some of them to be as much as 28 billion light years distant. I am amazed by the power of faith that allows us to entertain notions of creation events that defy the natural laws we have discovered.

Quote from: the link
Some quasars display changes in luminosity which are rapid in the optical range and even more rapid in the X-rays. This implies that they are small (Solar System sized or less) because an object cannot change faster than the time it takes light to travel from one end to the other; but relativistic beaming of jets pointed nearly directly toward us explains the most extreme cases. The highest redshift known for a quasar (as of December 2007) is 6.43,[2] which corresponds (assuming the currently-accepted value of 71 for the Hubble Constant) to a distance of approximately 28 billion light-years. (N.B. there are some subtleties in distance definitions in cosmology, so that distances greater than 13.7 billion light-years, or even greater than 27.4 = 2x13.7 billion light-years, can occur.)
« Last Edit: 31/10/2009 12:34:37 by Vern »
 

Offline Soul Surfer

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Where is our local quasar remnant?
« Reply #7 on: 01/11/2009 19:02:47 »
Every large galaxy was probably a quasar at some time or other because all that a quasar is is a "feeding" black hole.  Active galactic nuclei are essentially weak quasars.   They were much more common in the past probably because of their size and the availability of material local to the black hole.  Quasars are very variable and probably go through many outbursts and quiet spells on the timescale of the age of the universe.
 

Offline LeeE

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Where is our local quasar remnant?
« Reply #8 on: 01/11/2009 20:25:25 »
Hmm... I'm mostly inclined to go along with you SoulSurfer,except that I think that some AGN's have been calculated to have similar on-axis energies to quasars.  I can accept their short-term irregularities too, as long as the Schwarzchild radius of the BH is less than the duration of the irregularities.

In the end though, I still find it a bit strange that no obvious ex-quasar remnants have been observed locally.
 

Offline Soul Surfer

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Where is our local quasar remnant?
« Reply #9 on: 02/11/2009 23:43:21 »
Putting a one million solar mass black hole into the scale of things.  It is about twice the diameter of the sun or a few light seconds across

Few people realise quite how small black holes realy are and how difficult it would be to fall into them from a distance if there was nothing in the way.

even the very most massive black holes known are only about as big as the orbits of the outer planets.
 

Offline LeeE

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Where is our local quasar remnant?
« Reply #10 on: 03/11/2009 11:07:49 »
Putting a one million solar mass black hole into the scale of things.  It is about twice the diameter of the sun or a few light seconds across

Few people realise quite how small black holes realy are and how difficult it would be to fall into them from a distance if there was nothing in the way.

even the very most massive black holes known are only about as big as the orbits of the outer planets.

Sure, on an astronomical scale, the diameter of a one million solar mass BH would be negligible, but I suspect that we would have detected any relatively local ones by their lensing.
 

Offline PhysBang

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Where is our local quasar remnant?
« Reply #11 on: 03/11/2009 12:59:28 »
The black hole in our galaxy is obscured (in the visible spectrum) from us by dust, as is everything else in the centre of the galaxy. Fortunately, its gravitational influence can be detected by looking in the infrared at the motion of stars. I'm not sure if anyone has yet proposed using gravitational lensing to look at it. It would be a great test if it is possible.
 

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Where is our local quasar remnant?
« Reply #11 on: 03/11/2009 12:59:28 »

 

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