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24 votes
Accepted

What happens when the quasar remnants reach Earth in 3 million years?

Probably nothing of practical interest. Keep in mind that the gas in the shock wave in question is much less dense than our Solar wind. The X-rays generated in the shock wave aren't much intense ...
fraxinus's user avatar
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21 votes
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What is the mechanism through which mass is converted to thermal energy in the accretion disc of a black hole?

The "mass" falling in is the rest mass (at infinity). As the matter falls it gains kinetic energy. Most of the matter cannot fall directly into the black hole because it encounters a ...
ProfRob's user avatar
  • 153k
16 votes

How can gravitational lensing makes a quasar appear brighter?

The quasar gives out light in all directions. The light spreads out in space. Only a very small amount of that light would be pointed exactly in the direction of your telescope. But if a large galaxy ...
James K's user avatar
  • 123k
13 votes
Accepted

What does "Effective radius of [CII] line is 1.4 kpc" mean?

Defining the radius As the surface brightness (SB) of extended objects does not reach zero at some well-defined radius, we need a measure to be able to compare various objects. Probably the most used ...
pela's user avatar
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12 votes
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Quasar mass and accretion rates

Tricky to say for sure, but I would imagine it comes about from measurements of the luminosity and inference of the black hole mass in such systems. The most extreme objects radiate at the Eddington ...
ProfRob's user avatar
  • 153k
12 votes

What happens when the quasar remnants reach Earth in 3 million years?

In astronomy, we generally use observer time uncorrected for distance (because we usually don't know the distance very well). The 6 Mya is the time that the x-rays from the event arrived at Earth, so ...
John Doty's user avatar
  • 1,909
10 votes

How are neutrinos produced in blazar jets?

Neutrinos are typically produced in AGN jets through what we refer to as hadronic processes. Protons are accelerated to relativistic speeds and interact with nearby photons. Depending on the ...
HDE 226868's user avatar
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10 votes
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Why are quasars so far away that they couldn't be optically resolved in the 1950's?

Quasars have a very low density at the present epoch, but were much more common in the past. Their co-moving space density peaks at redshifts of 2-3. The evolving space density of bright quasars. ...
ProfRob's user avatar
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8 votes
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What "external illumination" source causes the heating of a quasar's accretion disc?

Ok, let's understand it this way: The central engine of an Active Galactic Nucleus (AGN) is a supermassive black hole, which accretes matter from its surroundings. This accretion process forms a disk ...
vivek's user avatar
  • 106
8 votes
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On the "periodic" lightcurves of Active Galactic Nuclei

I don't think what you're seeing is periodicity; my bet is that it's just stochastic red noise. Searches for periodicity or quasi-periodic oscillations (QPOs) in AGN light curves is a difficult and at ...
HDE 226868's user avatar
  • 36.6k
7 votes

Quasar Redshifts

The optical emission lines of quasars do not come from sufficiently close the the central supermassive black hole to be appreciably gravitationally redshifted. If they did arise from gas near the "...
ProfRob's user avatar
  • 153k
7 votes

Why would the merger of spinning black holes within the accretion disk of a supermassive black hole cause them to "shoot straight up" out of the disk?

Let me see if I can try answering both parts of your question. The key is a combination of two things: 1) Most of the binary BHs in an accretion disk will have their binary orbits in the same plane as ...
Peter Erwin's user avatar
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7 votes
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Is quasar 2M1310-1714 outside the observable universe?

The redshift of the quasar is 1.975, so it is nowhere near the edge of the observable universe. 17 billion light years is the comoving distance (i.e. where it is now), as you can confirm with this ...
ProfRob's user avatar
  • 153k
6 votes
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How does science knows what is the early universe?

I assume you're referring to the recent press release about the quasar J043947.08+163415.7, observed recently using Hubble. The paper about the observations details how the authors measured the ...
HDE 226868's user avatar
  • 36.6k
6 votes
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Can we extract power from quasars?

We could, but there isn't enough energy to make it worthwhile. These types of radiation are referred to as "highly energetic" because each individual particle (or very short burst) has comparatively ...
Steve Linton's user avatar
  • 10.3k
6 votes
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light emission of quasars

The statement "They're only emitting infrared light" is wrong, or at least poorly phrased. The Ly$\alpha$ forest The Ly$\alpha$ forest (LAF) is caused by the spectrum of the quasar being redshifted ...
pela's user avatar
  • 38.6k
6 votes

Could quasars be interior to the event horizon of a SMBH?

the Quasar Age or Quasar Epoch has ended. As pointed out by James K., the Quasar epoch has not ended. Today quasars are rarer then some Gyr ago, but they are still here. The closest one is about 600 ...
Prallax's user avatar
  • 4,431
6 votes
Accepted

What does "TON" in TON 618 stand for?

Tonantzitla Observatory. See https://en.wikipedia.org/wiki/TON_618 and https://en.wikipedia.org/wiki/Tonantzintla_Observatory
Pierre Paquette's user avatar
5 votes

Is it possible that quasars are not powered by black holes but some other kind of compact, massive object?

The solution to your question is surprisingly simple, I think: A quasar that puts out energy around Eddington luminosity or higher, must accrete at a certain rate, corresponding to the energy output. ...
AtmosphericPrisonEscape's user avatar
5 votes

How to find the distance between two quasars

Edit: I found you a very relevant paper! http://arxiv.org/pdf/astro-ph/0007341v1.pdf seems to be solving exactly your problems for sources with arbitrary angular separation $\alpha$. Equations (12) ...
cnosam's user avatar
  • 106
5 votes

How to interpret this spectrum of the "new DESI Quasar at z = 6.53"; what causes the big edge at about 9150 Angstroms?

The jump occurs at the redshifted wavelength of the Lyman-$\alpha$ line, so this is the Gunn-Peterson trough, which is caused by neutral hydrogen in the intergalactic medium suppressing any radiation ...
Thomas's user avatar
  • 3,494
5 votes

How to interpret this spectrum of the "new DESI Quasar at z = 6.53"; what causes the big edge at about 9150 Angstroms?

Thomas' answer is completely correct, I'd just like to elaborate a little on the reason for such a spectrum. Quasar spectra generally have broad emission lines, in particular Lyman $\alpha$ at a rest ...
pela's user avatar
  • 38.6k
4 votes

Why are all quasars so far away?

in the early universe there was more diffuse matter in gaseous form available to the black holes. The galaxies were more foggy with diffuse matter and less void, so a BH travelling through a galaxy ...
bandybabboon's user avatar
  • 4,250
4 votes

Redshift quantization

There's a pretty comprehensive wikipedia page on the subject. In summary.... Throughout the 2000's conflicting results were published using the same data. The conflict seems to center on the ...
christopherlovell's user avatar
4 votes

Gravitational lensing of quasars

Yes, there are many. One of the first, if not the first was the radio lensed quasar B1938+666, in which a near-IR Einstein ring was reported by King et al. (1998). The answer to your real question ...
ProfRob's user avatar
  • 153k
4 votes

How to convert luminosity at rest frame wavelength of 1450 A to absolute magnitude at 1450 A?

The absolute magnitude of an object is defined as the brightness of the object observed at a distance of $d = 10\,\mathrm{pc}$. With this distance, you can convert the luminosity density $L_\nu$ in $\...
pela's user avatar
  • 38.6k
4 votes
Accepted

What enhances the capture and merge rates of pairs of small black holes orbiting around supermassive black holes?

I would think that the same reason that a gas disk enhances the growth of planetesimals. Drag from the disk enforces circular, co-planar orbits, which in turn means that objects that get close to each ...
ProfRob's user avatar
  • 153k
4 votes

Could life develop in a galaxy with a quasar at its centre?

There is some evidence that the Milky Way black hole has been active in the relatively recent past. Joss Bland-Hawthorn (et.al) describe large-scale ionization cones in the Galaxy that they say ...
James K's user avatar
  • 123k
3 votes
Accepted

What values can a color index variable get?

The only physical mechanism I can think of for quasars to have such a large difference in two bands would be at very high redshift ($z\gtrsim6$) where you have the Gunn-Peterson trough completely ...
pela's user avatar
  • 38.6k

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