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Questions tagged [quasars]

Questions about quasi-stellar radio sources, active galactic nuclei that are far away and quite old.

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57 views

How does science knows what is the early universe?

I've read about Hubble seeing the brightest quasar in the early universe. Question is, how does science knows what is early and what is late? Please correct me if I'm wondering, but after the big ...
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2answers
67 views

Can I take logarithms of magnitudes (which are already log) [closed]

I'm investigating the relationship between the magnitude of quasars in various wavelengths, and their redshift $z$. I've found that if I take the $log$-$mod$-transform ($L_{mag}$) of the magnitudes, ...
2
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0answers
37 views

What fractions of matter are retained and displaced by quasars?

Following on from a query concerning quasar mass, what fraction of matter is ejected compared to matter that is lost to the BH? Is there a graph that describes the fractions of the mass of quasars ...
5
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1answer
71 views

3C273 jet mass estimate

In this picture of 3C273, we can see a jet—estimated to be around 200,000 light-years long—being emitted. I'm trying to find an estimate for the mass of the jet. It's a stream of ...
13
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2answers
573 views

Quasar mass and accretion rates

This page on Wikipedia -- Quasars mentions that the "The largest known [quasar] is estimated to consume matter equivalent to 600 Earths per minute". However, there is no citation for this comment. How ...
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0answers
34 views

Quasar Spin and Luminosity of its Jet

What is the relation between the spin of a quasar and the luminosity of the jet emitted by the same quasar?
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2answers
76 views

Can we extract power from quasars? [closed]

As they say, "In cosmos near earth but beyond atmosphere there are too much dangerous and powerful radiation frm quasars or gammy burst .,etc". So if there is so much cosmic radiations being emitted, ...
4
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1answer
80 views

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

AFAIK, objects in the universe thought to be black holes show evidence of radiatively inefficient accretion flow. But is this the case with Quasars? If not, is there a possibility that the core of a ...
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2answers
137 views

Is there an official list of objects in the sky?

I would like to know how many known quasars there are in the Universe as well as x-ray binary black holes (not Neutron stars) but I don't seem to be able to. I also want to know how many black holes ...
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0answers
39 views

Differences between Seyfert galaxies and Quasars [duplicate]

Everywhere I read, the definition of Seyfert galaxies coincides with quasars: both have a SMBH in the nucleus, are active and bright, and tend to emit blue in visible light due to synchroton radiation ...
6
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1answer
87 views

Gravitational lensing of quasars

Are there any cases in which the gravitational lensing of a quasar has been observed in both visible light and in radio waves, and if so, is the radio-wave resolution good enough to show that the ...
1
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1answer
65 views

Has the Lyman-alpha forest ever been used to test Arp's theory?

Has the Lyman-alpha forest ever been used to test Halton Arp's theory that quasars are not cosmological but instead are ejected from relatively near-by galaxies? If Arp was right, then the spectra of ...
2
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1answer
103 views

What resolution is needed to see a quasar through the galactic center?

The center of the galaxy is densely packed with stars and obscured by a whole lot of dust between us and it. For those reasons, groups that study the motion of stars around the super-massive black-...
3
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1answer
88 views

Why do Seyfert Galaxies emit less energy than Quasars and Blazars, and how is the emitted energy measured?

When I was reading information about QSOs on a website, it said that Seyfert Galaxies emit less energy than Quasars and QSOs. Why do Seyfert Galaxies emit less energy than quasars, and how is this ...
3
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1answer
294 views

What is high redshift?

I'm curious about the difference between low redshift and high redshift universe. Is there any defined limit of redshift beyond which we call things high redshifted?
4
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1answer
273 views

Redshift quantization

A full disclosure to begin with: I'm a PhD student in mathematics and while I understand most of standard cosmological-astronomical terms and I've followed a one semester course on cosmology, I don't ...
2
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1answer
57 views

Accretion discs emitting jets [duplicate]

When there are accretion discs jets of particles or radiations will be emitted in the direction parallel to the rotational axis. My beginner level astronomy textbook just says that it is due to ...
0
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1answer
119 views

Extraction of error spectrum in Sloan Digital Sky Survey

I need to know does SDSS spectrum contains error spectrum as well? http://www.sdss.org/dr12/spectro/spectro_basics/#AbouttheSpectra The above link says, further HDU's contain error spectrum and than ...
2
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1answer
177 views

What would be the outcome for life in our galaxy if the merger of the Milky Way and Andromeda creates a Quasar?

If predictions are correct, the Milky Way and Andromeda are set to collide in around 4 billion years. If, when this occurs, a Quasar is formed by matter being accreted to the common galactic center (...
4
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3answers
858 views

Quasars and Gamma Ray Bursts

Has there been any study to suggest that either quasars of gamma ray bursts are more detectable from further distances in the universe? I've read that quasars are the most powerful energy in the ...
8
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1answer
185 views

What is the scale of things you can see with gravitational lensing?

I'm trying to understand the examples of gravity lensing (using the general relativity property of large masses to bend light like a lens). Most of the examples I see are of some galaxy (presumably ...
2
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1answer
212 views

Has the most luminous object in the universe been found?

It's hard to search through the entire (observable) universe, but the most luminous thing there is must on the other hand be easy to find. Can we now say that the most luminous quasar we know, is the (...
2
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2answers
263 views

What is projected separation and how can I make sense of its unit (h^-1 kpc)?

I have been reading this paper on the separation of a binary quasar in which it states: At a projected separation of 8.3/h kpc (Omega_matter = 1), CTQ 839 would be the smallest projected separation ...
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1answer
125 views

Does 2 merging black holes necessarily make a quasar?

2 black holes are about to merge to become a larger black hole. Does this mean it'll become a quasar? From what I know, quasars are supermassive black holes or a collective amount of them. So, if it ...
2
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2answers
924 views

If quasars are powered by black holes, why are they so bright?

If a black hole can swallow everything, even light, then how can a black hole power anything, particularly something as bright as a quasar. Why doesn't the black hole swallow the light of the quasar? ...
9
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1answer
104 views

How to find the distance between two quasars

I want to calculate the distance between two quasars of which I know the angular position and the red shift. Let $Q_1=(\alpha_1,\delta_1, z_1)$ and $Q_2=(\alpha 2,\delta 2, z_2)$ and suppose $z_2 > ...
2
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1answer
320 views

Mass distribution in the early universe

The latest big quasar find at ~12.8 bn LJ with an estimated mass of 12 bn M☉ (see e.g. http://www.newscientist.com/article/mg22530104.000-ancient-black-hole-had-an-inexplicable-growth-spurt.html) puts ...
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5answers
4k views

Why are all quasars so far away?

Why are all quasars so far away? If the universe is homogeneous, we could expect to have a homogeneous distribution of quasars, but all of then seem to be far away from Earth. Why is that?
7
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1answer
282 views

How often does the supermassive black hole in the Milky Way become a quasar?

My current interest is black holes and quasars. I was wondering how often they erupt--specifically ours? Would it be blindingly bright on Earth? Finally, would there be any effects that would alter ...
6
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2answers
5k views

Difference between quasar and Active Galactic Nuclei?

Are there any differences between quasars and Active Galactic Nuclei (AGN)? As I understand it, they are both caused by extremely luminous electromagnetic emission from material accreting onto a ...