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Questions tagged [quasars]

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Why does the peak of quasar distribution move from near to far with increasing magnitude?

I made a little tool to examine the distribution of quasars in various catalogs, including SDSS DR16Q: If you check the +/- box, and move the magnitude slider from low (-20) to high (-30), the peak of ...
MikeHelland's user avatar
4 votes
1 answer
139 views

Quasars to a galaxy

Do quasars collapse and make a galaxy or do they eventually spew out enough matter to make one? Because I heard they are the center of galaxies, and I wonder if they can collapse from their own ...
Kellan Heerdegen's user avatar
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Optical emission seen in Relativistic Jets from Quasars

So, I came across a very exciting paper on arXiv today. Here, they talk about the Hubble Space Telescope (HST) imaging of the host galaxy of the very first known quasar- 3C 273. My question is related ...
vivek's user avatar
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Has anybody measured the Schwarzschild radius of a black hole and does the radius equal the radius predicted from the mass?

Have schwarzschild radii been measured from quasars or lensing black holes of known mass?
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Conservation of energy in quasar outflows?

I found this article about the behavior of quasar outflows in cosmology and how they can create a magnetic field. In section 2.1.4., the authors say that when a quasar produces a "wave" or ...
vengaq's user avatar
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2 answers
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Does the HD1 Quasar explain how Super Massive Black Holes Form?

The galaxy HD1 has a 150M SM BH at its core. HD1 formed SUPER early in the universal history. It is 13.5B LY away (basically 330 M years after the big bang)... So does this show that the clumpiness ...
Rick's user avatar
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1 vote
1 answer
36 views

X-Ray data of AGN

I have downloaded spectra of a quasar from the Sloan Digital Sky Survey (SDSS), but it has data in Visible Range. I need data of same quasar in the X-Ray region and I think SDSS don't have data in the ...
3 votes
1 answer
972 views

How do we know that quasars are not white holes?

White holes are speculative in nature. Black holes are known to exist (supermassive black holes in galactic nuclei and stellar-mass black holes in binaries). My question: if white holes are expected ...
Daddy Kropotkin's user avatar
2 votes
0 answers
60 views

How do black holes get their magnetic fields?

I imagine the magnetic field comes from the accretion disk. But what causes it to "spring" upward?
Orangeman's user avatar
2 votes
2 answers
351 views

How does a quasar convert mass to energy?

I'm trying to understand where the energy for a quasar comes from and specifically if it comes from converting mass to energy. I know that as matter falls into a black hole gravitational energy is ...
QuasarBoy99's user avatar
0 votes
1 answer
29 views

Is brightness of quasar jets related to the size of the black hole

I think I read somewhere that brightness of infra red light from quasar( or UV light but red shifted to IR light) is related to the size of the black hole. Why is that?
never took courses but why's user avatar
0 votes
1 answer
77 views

How do I know that I am observing a quasar?

When I find a faint object on the sky that looks like a star or a far away galaxy how do I know that it really is a quasar? I guess that I could first compare the apparent magnitude (how bright it ...
Agerhell's user avatar
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4 votes
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What is Cosmic Downsizing?

I've had a quick look at a few lecture pdfs and papers as supplementals to my own given lecture notes, but I can't seem to get a proper explanation for what cosmic downsizing is. The closest ...
Wrothschild's user avatar
1 vote
0 answers
125 views

Oscillations in an emission line spectrum

From my basic physics background, I know that when an electron gets enough energy from a photon or whatever it may be, it has the capacity to jump up to a specific energy level. When it loses the ...
ScienceGirl1234's user avatar
2 votes
0 answers
247 views

Can gravitational waves be absorbed near a quasar?

As the Quasar Wikipedia article explains, a quasar is powered by gas falling into a supermassive black hole at the center of a galaxy. The Luminous infrared galaxy article says that, in extreme cases, ...
mmesser314's user avatar
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2 answers
409 views

How do quasars produce light?

Wikipedia states that the radiation of quasars is partially nonthermal (i.e. not blackbody). Well, what percentage of the total radiation isn't black body? For some reason Wikipedia doesn't give a ...
Bill's user avatar
  • 393
4 votes
1 answer
209 views

Why can't friction in an accretion disk radiate away enough of the angular momentum do create inward spiral?

As almost every source that I'd found explains, it was a challenge for scientists to understand the mechanism by which the total angular momentum in the accretion disc was conserved, while taking the ...
Max's user avatar
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4 votes
2 answers
413 views

Could quasars produce elements heavier than oxygen?

I have read that supernovae are the main producers of elements heavier than oxygen. I just wonder whether quasars, which have been around a long time just like supernovae have, could have had a ...
Richard Peterson's user avatar
4 votes
2 answers
300 views

How do we know that Quasars actually produce collimated jets?

How did astrophysicists know this? Of course it's very difficult to directly see the jets from Quasars, so I'm wondering how did they come to the conclusion that Quasars produce collimated jets or ...
user43783's user avatar
  • 1,137
55 votes
2 answers
7k views

2002 research: speed of light slowing down?

Back in 2002 there was some research published hinting that $c$ may have been faster at some distant point. It was based on measurements of the fine-structure constant, $$ \alpha = \frac1{4\pi\...
Errol Hunt's user avatar
  • 1,116
4 votes
1 answer
222 views

What is a quasar flux ratio anomaly?

In the context of strongly lensed, multiply-imaged quasar observations, I sometimes hear about "flux ratio anomalies". What are these? Why are they important?
Kyle Oman's user avatar
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2 votes
1 answer
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Quasar redshift

The quasar 3C 273 has a redshift z=0.158. A question in a textbook: could this be a gravitational redshift instead of cosmological (=resulting from the expansion of space)? My answer: no. Firstly, ...
gamma1954's user avatar
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Black hole accretion disks and quasars

Are 'accretion disk of a black hole' and 'quasar' synonymous? If not, what's the difference?
Satyajit Sen's user avatar
5 votes
1 answer
1k views

What is the difference between a quasar and an Active Galactic Nucleus (AGN)?

In answering another Phys.SE question about quasars - Why no new quasars? - an issue arose about which object is the nearest quasar. That got me puzzled. To what is the label "quasar" attached, as ...
ProfRob's user avatar
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2 votes
1 answer
215 views

Why no new quasars?

Why are there no quasars younger than 13 billion years old? I have researched the emission spectrum of quasars and found only hydrogen. Could it be that after a billion years after the Big Bang, ...
Steve Ruiz's user avatar
6 votes
1 answer
290 views

History of the Milky Way-Quasar

Was our Milky Way a Quasar many years ago? I heard that it is difficult to fuel quasars for many billions of years, after a quasar finishes accreting the surrounding gas and dust, it becomes an ...
Daniel Aguayo Vera's user avatar
13 votes
2 answers
4k views

Do quasars exist today?

Are there likely to be any quasars right now, or are all the ones we're seeing old galaxies today, like the Milky Way?
MissingUTAH's user avatar
23 votes
2 answers
10k views

How can Quasars emit anything if they're black holes?

We've heard it many times, nothing can escape the gravity of a black hole, even light once it's past the event horizon. If this is true, how can a black hole emit anything? Quasars are massive black ...
user avatar
9 votes
2 answers
486 views

Which way do black hole jets spin?

The centers of black holes and quasars often have jets coming out the two poles of an accretion disk, say north and south. Is it known if the two jets spin in the same direction or opposite ...
AnimatedPhysics's user avatar