Why are Quasars all far away? Edge of the Universe?

[Whack-a-Mole]

Ok, I have been in enough discussions regarding the nature of the Universe around here to know that defining an “edge” to the Universe is a meaningless concept (i.e what is north of the North Pole).

However, Quasars puzzle me. I thought one of the basic tenets of cosmology is that the universe, on large scales, is pretty much the same whichever way you look (no one place is particularly unique from any other place). But how can that be with Quasars only appearing at the most extreme range of our best radio telescopes? It is as if there is an edge else how can one explain that there are no nearby quasars? Just dumb luck it worked out that way?

Again, I know there is no “edge” but what gives here?

[The_Hamster_King]

The further away something is, the longer its light takes to get here. Quasars were a phase that the entire universe went through early in its history, but the only ones we see now are the ones so far away that their light is just now arriving.

[Triskadecamus]

Perhaps Quasars are very old. The sorts of energy budgets that create them, and sustain their existence were only available in the very early era of the universe’s history. In the geometry of astronomy, old equals distant. So, the reason we only see them at the extreme of our observational reach is that all the ones around here were gone long ago, and the only ones we can see are the ones that were far enough away that the light just got here.

Tris

“It should be possible to explain the laws of physics to a barmaid.” ~ Albert Einstein ~
“You should see the place where Einstein used to drink!” ~ Triskadecamus ~

[Q.E.D]

If there are no quasars closer than 10-12 billion LY or so, it simply means that the conditions necessary for their formation only existed in the Universe more than 10-12 billion years ago.

[David_Simmons]

@Whack-a-Mole

Ok, I have been in enough discussions regarding the nature of the Universe around here to know that defining an “edge” to the Universe is a meaningless concept (i.e what is north of the North Pole).

However, Quasars puzzle me. I thought one of the basic tenets of cosmology is that the universe, on large scales, is pretty much the same whichever way you look (no one place is particularly unique from any other place). But how can that be with Quasars only appearing at the most extreme range of our best radio telescopes? It is as if there is an edge else how can one explain that there are no nearby quasars? Just dumb luck it worked out that way?

Again, I know there is no “edge” but what gives here?

I think the universe is the same pretty much wherever you look. No matter where you look, quasars show a large red shift indicating a great distance and age. In fact, as I recall this is what finally caused astronomer Fred Hoyle to abandon his steady state model of the universe. I.e. all quasars are ancient therefore conditions must have been different then than they are now.

Here’s what Britannica has about them: “A more spectacular example of galaxy evolution is provided by quasars. From the statistics of the frequency of different redshifts, which represent different distances and different epochs in the past, it has been determined that the quasar phenomenon occurred most frequently a few billion years after the big bang (the exact amount of time is uncertain because astronomers do not as yetknow enough about the geometry or the age of the universe). It appears that conditions did not become suitable for quasar formation until after the galaxies had formed and separated. Today quasars are quite rare, but many galaxies have miniature versions of them in their nuclei in the form of less massive yet remarkably energetic objects.”

I suspect some of that is out of date and an astronomy expert will be along shortly to bring it up to the present.

[Squink]

Here is a quasar that is only 2 billion light years away. Apparently there are several which are even closer:

Nearby Quasars Result From Galactic Encounters, VLA Studies Indicate
…
The researchers chose three quasars at distances of 670 million to 830 million light-years. The three galaxies surrounding these quasars had different appearances in optical images: one showed evidence of mild interaction with a neighboring galaxy; one appeared undisturbed but had a nearby neighbor; and the third appeared undisturbed and alone. When imaged with the VLA, all three showed strong evidence that their gas had been disrupted by an encounter with another galaxy.

[Joe_Random]

@Whack-a-Mole

I thought one of the basic tenets of cosmology is that the universe, on large scales, is pretty much the same whichever way you look (no one place is particularly unique from any other place). But how can that be with Quasars only appearing at the most extreme range of our best radio telescopes?

[queue Star Wars theme]
Long, long ago in a galaxy far, far away…
[/SW theme]

My point being that telescopes aren’t just looking at stuff that’s far away. They’re looking at stuff that happened way, waaaay in the past, too. The farther, distance-wise, you get from the Earth, the further into the past you’re seeing. So it’s not that quasars are all far away from us, just that they’re all remnants from the early universe that don’t appear to be around anymore.

On preview, I see that this has already been responed to, but I refuse to admit that I wasted time composing a perfectly good response, so there.

[Whack-a-Mole]

I’m still a bit stuck on understanding this so I’ll flail around a bit here and see if anyone comes to the rescue.

• I get the part that whatever is needed to make a Quasar only happened in the relatively young universe.

• Yet the Big Bang should not be thought of like a stick of dynamite going boom. It happened everywhere at once so quasars presumably should have been scattered roughly equally all over space.

• On the flip side I know that all things in the universe are moving away from each other so follow the earlier posts.

• On the flip-flip side wouldn’t one suppose there are places in the universe close (relatively speaking compared to us) to quasars? Doesn’t this make for a non-uniform universe as some places can be considered quite distinct (i.e. quasars nearby in one direction and none to be seen in the opposite direction)?

[David_Simmons]

@Joe Random

On preview, I see that this has already been responed to, but I refuse to admit that I wasted time composing a perfectly good response, so there.

Attaboy!! Never say die.

[Triskadecamus]

@Whack-a-Mole

On the flip-flip side wouldn’t one suppose there are places in the universe close (relatively speaking compared to us) to quasars? Doesn’t this make for a non-uniform universe as some places can be considered quite distinct (i.e. quasars nearby in one direction and none to be seen in the opposite direction)?

There were places in the universe close to the Quasars. But that was a long time ago. The quasars are gone, now, and only the places remain. This might well be one of them, right here, but our local quasar just faded out, ten or twelve billion years ago. Things haven’t been the same, since, let me tell you.

In a few hundred billion years, folks will ask the same questions about stars. You know, “Why don’t we see stars nearby? All the stars we can detect with our graviscopes are fifty billion light years away? Why aren’t there any stars around here?”

Tris

“You could park a car in the shadow of his ass.” ~ Geena Davis, in Thelma and Louise ~

[The_Hamster_King]

@Whack-a-Mole

• On the flip-flip side wouldn’t one suppose there are places in the universe close (relatively speaking compared to us) to quasars? Doesn’t this make for a non-uniform universe as some places can be considered quite distinct (i.e. quasars nearby in one direction and none to be seen in the opposite direction)?

No matter where you are in the universe, you’ll see large numbers of quasars about 10-15 billion light years away in all directions.

The quasars we see now aren’t there anymore. They existed 15 billion years ago. We can only see them now because it took their light that long to reach us.

Meanwhile, the light from the quasars that were near us back then is 15 billiion light years away and racing ever farther away with every passing second.

[Chronos]

I guess this report wasn’t very memorable… Sigh.

But the key to Whack-a-Mole’s question, I think, is that quasars are (or rather, were) scattered pretty uniformly through the Universe. There are, in fact, galaxies close to us which were once quasars. The key is that they aren’t quasars any more. All of the quasars in the Universe have quieted down now, so the only ones we can see are the distant ones whose light is still en route.

[Joe_Random]

@Whack-a-Mole

Yet the Big Bang should not be thought of like a stick of dynamite going boom. It happened everywhere at once so quasars presumably should have been scattered roughly equally all over space.

I’m sure that they were . . . when they actually existed.

On the flip-flip side wouldn’t one suppose there are places in the universe close (relatively speaking compared to us) to quasars?

Nope. If you somehow managed to violate every known law of physics and instantly teleported to some planet in the vicinity of where we can currently see quasars, you wouldn’t be near any quasars at all. This is because we’re seeing light that originated from those quasars billions of years ago. They have long since ceased to exist, even though the photons they spewed into space are just now getting here.

Doesn’t this make for a non-uniform universe as some places can be considered quite distinct (i.e. quasars nearby in one direction and none to be seen in the opposite direction)?

I’m pretty sure (no cite) that we can see quasars in every direction. And if you moved to another point in the universe, you’d see the same thing. In fact, if you did that little teleoprtation trick I mentioned earlier, and then turned a radio telescope back on the Milky Way, you’d likely see a few quasars here, since there probably were quasars around here several billion years ago.

[Colibri]

All of the primordial quasars that were originally in the space close to us changed into something else 10 billion years ago.

All the quasars that we “see” at a great distance from us also no longer exist. They also changed into something else 10 billion years ago. We only see them because we are looking far back into the past, because of the time it has taken for the light to reach us from where these quasers once were.

Aside from the few relatively recent quasars that Squink mentions, they simply do not exist in the universe any more, so there is no place that is “closer” to any of them. From anyplace in the universe, they will always appear to be more than 10-12 billion light years away. Any light from closer started traveling after quasars ceased to exist, and so won’t show them.

[Whack-a-Mole]

@Chronos

I guess this report wasn’t very memorable… Sigh.

Thanks Chronos. I get it now (and see what others were trying to crowbar into my thick head).

If it makes you feel better I did not forget that piece…just missed it. I’ll remember that one from now on though.

Too bad though that we will never be able to go out and see one up close. If I invent a teleportation device (conveniently ignoring all the issues that raises) I’ll pop out there only to find no quasar but looking back at where I came from might well see one sitting next door to where I just left! This stuff is so much fun to melt your brain with!

[Whack-a-Mole]

Ack…I hit reply and then got busy with something else only to finish my last post some time later and see Joe Random hit on everything I said (and then some). Not trying to repeat others…just need to preview more. Thanks for all the replies.

[scotandrsn]

Let’s get ourselves up to speed on quasars. Not pointing fingers, but some of what I’m reading here makes me wonder if some of us aren’t working from a VERY old understanding of what quasars are.

They were first discovered in 1963, as point-sources of light that were not stars. Hence the name “quasi-stellar objects” or “quasars”.

The reason we know they are not stars is that stars have a radiation spectrum that falls into a certain pattern, but quasars did not. We also realized that they are fairly large and extremely far away.

In the mid-1990s, astronomers began to realize what they might be.

If you’ve ever seen an amazing photo of a galaxy and then looked at one live through a telescope, you notice a certain brilliance missing. That’s because to get the photo, it must be overexposed. Dim things achieve a more visible brightness, and bright things wash out to a very bright white.

Here is a fairly wide-field picture of Galaxy M33. It appears completely blown out.

In a tighter shot of M33. The overexposure has let us see some of the outer structure of the galaxy, but notice that the core is still washed out.

Here is an even tighter shot of the core area of M33. We can see more detail, but there is still a very bright area in the center that the overexposure has washed out.

So the closer we look at a galaxy, more we realize that there is a very bright point-source in the middle. Sound familiar?

What then, would be most visible about this galaxy if we were to observe it from 10-12 billion light-years away?

IOW, quasars are galaxy cores (specifically the cores of supermassive galaxies), which we’ve know for about 10 years.

More information here

The fact that they are so far away means that quasars represent an early stage of formation of such galaxies.

[scotandrsn]

And of course it took me so long to put my post together I didn’t see Chronos’ link to his Staff Report until I’d submitted :smack:

[Chronos]

All galaxies have bright cores (at least, brighter than the outlying regions), but that’s not the same phenomenon as quasars. The bright core of, say, the Milky Way is just due to the fact that there are a lot of stars giving off light in the core. But a quasar is significantly brighter than all of the stars in a galaxy combined, and is smaller than the Solar System. You’re not going to get that just by putting a bunch of stars close together.

[mangeorge]

Damned interesting thread, and links. Thanks, Whack-a-Mole.

Peace,
mangeorge