Questions tagged [quasars]

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

Filter by
Sorted by
Tagged with
1
vote
1answer
33 views

Regions and size of an AGN

In this diagram of the regions and approximate scale of an AGN: which is from this paper, what do the x and y scales log(z/pc) and ...
1
vote
0answers
36 views

What compounds are present in 3C273?

Anyone know if we have any chemical reactions occuring in this quasar?
3
votes
0answers
31 views

Number of obscured AGN compared to unobscured AGN

Urry and Padovani 1995 proposed a unified model for Active Galactic Nuclei, which has since been recognised as a good model for AGN. If AGN are randomly oriented, then I'd expect there to be more ...
1
vote
0answers
35 views

Causes of emission of accretion disk

As far as I can see, there are two main sources for the emission of energy from an accretion disk: release of gravitational potential energy of the infalling matter; friction from differential ...
2
votes
2answers
360 views

Quasar Redshifts

How can the gravitational redshift of a very distant quasar be distinguished from its cosmological redshift? Quasars are very massive objects,thought to be supermassive black holes,so therefore must ...
1
vote
1answer
12 views

How to convert the observed magnitude of a Quasar to it's bolometric luminosity?

How can I convert the observed magnitude to Bolometric Luminosity? I know the relation for the star but should it be same for a Quasar? Basically I want to convert the X-axis of this plot to ...
0
votes
0answers
15 views

Anisotropy of quasar distribution

In a paper titled Arp, H. (1984). Distribution of quasars on the sky. Journal of Astrophysics and Astronomy, 5(1):31-41. at Journal of Astrophysics and Astronomy, Halton Arp wrote that there is ...
2
votes
0answers
151 views

Are quasars simply AGNs that are viewed from a particular angle?

I found the picture below in an answer to the post "Was the Milky Way ever a quasar". The picture is published on a website belonging to "NASA/IPAC Extragalactic Database". In the answer that has 16 "...
0
votes
1answer
49 views

What values can a color index variable get?

I am a statistician with love and passion for astronomy. I try to explain some outliers I found in the values of quasars - color indexes. I found four (4) values close to twenty (20). Is that ...
2
votes
0answers
60 views

Correction to inverse square law for cosmology

While reading about the discovery of quasars and the spectroscopic analysis of 3C 273 in this paper by Maarten Schmidt, I came across the following quote: At these distances, corrections to ...
10
votes
1answer
987 views

How can gravitational lensing makes a quasar appear brighter?

How can gravitational lensing makes a quasar brighter than it would in the absence of a foreground galaxy?
0
votes
2answers
123 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 ...
1
vote
2answers
72 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, ...
3
votes
0answers
46 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
votes
1answer
79 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
votes
2answers
727 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 ...
-1
votes
2answers
99 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
votes
1answer
90 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 ...
0
votes
2answers
149 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 ...
5
votes
1answer
96 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 ...
2
votes
1answer
79 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 ...
1
vote
1answer
117 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
votes
1answer
133 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 ...
2
votes
1answer
398 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?
3
votes
1answer
343 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
votes
1answer
66 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
votes
1answer
140 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
votes
1answer
245 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 (...
5
votes
3answers
1k 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
votes
1answer
216 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
votes
1answer
239 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
votes
2answers
369 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 ...
1
vote
1answer
144 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
votes
2answers
1k 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
votes
1answer
114 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
votes
1answer
326 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 ...
12
votes
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
votes
1answer
303 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
votes
2answers
6k 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 ...