Quasar Definition and 61 Threads

Regarding the new "quasar clock" data showing that time ran more slowly (~5-fold) shortly after the Big Bang: is it all based on the periodic variation in luminosity at various wavelengths of some quasars (and presumably explained by the special relativistic time dilation effect from "spatial...

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 an outflow, the material will be emitted with energy coming from both the quasar itself and the Hubble...

Given that a quasar is a super massive black hole with an accretion disk rotating at some significant percentage of the speed of light, what is the mechanism that generates the enormously luminous jet that emanates from the "poles" of the black hole that has become a quasar? a. The magnetic...

I am reading up on quasars because I am interested in the magnetic beams that emanate from their poles, accelerating material. I read that the magnetic beams are generated by the orbiting debris the quasar is consuming. Sorry, that doesn't sound right to me. I assumed the black hole core is...

When I see discussions about quasar redshift, exactly what are they talking about? I assume a quasar is similar to a black hole, so emits little radiation from the main mass. The light from a quasar comes principally from its jets of accelerated material, no? Which means the jet pointed...

Summary: If the furthest quasars we can see are let's say 13 billion light years away from us, then does this mean that the distance between us and that quasar was 13 billion light years at 13 billion years ago? To anyone educated in physics this might be a silly question but to me this is...

AIUI, a quasar is simply a black hole at the core of a galaxy that shoots out an enormous amount of energy along the axis of circulation. Since we are far from that axis, we cannot look into the Milky Way's core from that vantage point.

I understand quasars as black holes with an accretion disk and occassional jets of mass being shot out of the black hole from it's top and bottom. (Correct me if I'm wrong) If so, what is the actual possibility for that type of quasar to be rotated so heavily that it rotates on a horizontal...

Homework Statement You have decided to use a CCD camera to check if a 16th magnitude quasar is variable. With your telescope/camera combination, you know that a star with a magnitude of 0 would deliver 1 × 109 photons/second to one pixel, so this allows you to work out the photons/second from...

Hi, I'm currently trying to wrap my head around how the Ly-α forest works. This is what I have so far; A distant quasar produces these Ly-α photons, which occur when a hydrogen's electron drops from n=2 to n=1, and has a wavelength of around 121nm (depending on the exact transition). This...

Hello, Does quasars has a proper motion? I searched in different article and sometimes they are considered as objects having a proper motion and other times not. So I want some clarification. in which case can we say that a quasar has a proper motion? Thanks

Hello, What do you think about this article? https://arxiv.org/abs/1502.05850 Why and how do we mesure the Spectral Energy Distribution for quasars? Thanks

Does the new quasar http://news.bbc.co.uk/2/hi/science/nature/649059.stm indicate a challenge for models of quasars? Some of the ritz-type models do provide explanations for these, e.g., http://faculty.washington.edu/devasia/Physics/Devasia_cosmology.pdf It provides potential explanations to...

From deep galaxy counts, it is estimated that there are about 40 billion galaxies in the observable universe (not including probable multitudes of dwarf galaxies too faint to observe). Assuming that the mean age of these galaxies is 10 Gyr, and that each one goes through an AGN episode once...

Dear all, I am reading the paper "Cosmic dynamics in the era of Extremely Large Telescopes " by Liske et al. about redshift. I get the physical meaning of redshift drift, but when it comes to the error bars, I am confused. - Aren't the error bars given in equation (15) ? - Isn't this function...

Hello everyone! We observe the so-called Lyman-alpha forest in the spectrum of distant quasars and it is said that these multiple absorption lines are due to the presence of intergalactic HI clouds that absorb light at the wavelenght of 1216 A , the Lyman-alpha transition. My question is the...

Hello I just got interested into quasars and I have a question:What metric do you use for quasars?

The video: When Astrophysicists detected Quasars, they thought that they could not be more than a few light-days across as they were changing their brightness in just a few days. If we assume that they are light-years long, then the change in brightness from the other side would be observed...

I'm looking for help in understanding the meaning, nature and/or concept of singularity as such applies to the mechanics of a black hole ...

Homework Statement A quasar at redshift 0.3 is gravitationally lensed into two images by an elliptical galaxy at redshift 0.18. The two images of the quasar are separated from the center of the galaxy by 1.1 and 1.6 arcseconds, on opposite sides. One of the quasar images flares up in intensity...

There was some excitement a few months ago about the discovery of the Huge-LQG quasar structure, claimed to be the "largest structure in the Universe", which was said to violate the cosmological principle and the assumption of homogeneity of the Universe. Some previous threads on this topic on...

I know that the quasar is a huge source of energy, it can produce energy and light more that glaxies do ; so the question is how that can be possible and the quasar is a super massive Black hole which absorb every thing even Light couldn't escape ?! My Friend tell me when the Black Hole is...

Ive looked on a good number of websites, including the pedia, and i still feel like i didnt get a straight answer. What exactly is a quasar. Is it a black hole in the center of a galaxy? What is the physical makeup of a quasar?

Largest Structure in Universe Discovered http://news.yahoo.com/largest-structure-universe-discovered-093416167.html "An international team led by academics from the University of Central Lancashire (UCLan) has found the largest known structure in the universe. The team, led by Dr Roger...

Quasar Mass-Luminosity High Mass Turnoff Evolution and a Synchronization Puzzle It is unusual that a generation of researchers has the opportunity to completely rewrite, to replace major established scientific theories. The observation that quasars are turning on and off, at a specific mass...

Based on assumptions concerning the quasar mechanism it was assumed that quasars are turned on due to mergers. Observationally for z<1 where it is possible to determine if the quasar's associated galaxy is or is not merging it has been found that the quasar turn on does not correlate with...

Hi, Is Sagittarius A* the black hole a quasar or a blazar? As far as I've understood, AGNs are quasars, blazars or seyfert galaxies. Can someone please explain how the shockwaves/knots in the jets emitted by black holes can be detected?? Thanks :)

Quasars are galaxies which are very active at centre pulsars are dense stars... Since pulsars rotate very fast it can be a quasar gone crazy?

Hi there, I have got a real quick question. From where am I supposed to calculate the length of the jet ? http://i42.tinypic.com/w72929.jpg

Hello, could someone point out to me 1) Ironclad evidence of correlated light curves - and I mean a correlation that is beyond doubt - among lensed quasars 2) Morphological correspondence - e.g. corresponding jets - in images of lensed quasars. I can find sketchy cases which may be...

http://www.physorg.com/news/2011-06-astronomers-universe-distant-quasar.html The quasar that has just been found, named ULAS J1120+0641, is seen as it was only 770 million years after the Big Bang (redshift 7.1). It took 12.9 billion years for its light to reach us. These observations...

Our cosmology model follows the cosmological principle according to which we are not in a privileged place in the universe and there is homogeneity, but if you take a look at the distribution of quasars in the universe there seems to be a "quasar spherical void" roughly one billion lightyears...

I saw a real image of a quasar bursting out gamma radiation on a science channel program and I am having trouble finding the image, or any like it on the internet. All I can find are CG rendered things, and IR/UV images. The photo that I am referring to looked a bit like the Hubble deep field...

So I was looking some stuff up on Quasars on Wikipedia and noticed this picture. http://upload.wikimedia.org/wikipedia/commons/a/ab/2003-03-b-web.jpg It says that this is a Quasar Core. What exactly is the difference between the left and right pictures here? Did they block out the light...

A very interesting but speculative paper was published in the Physical Review and arXiv recently about the possibility of the former existence of Cosmic Strings at the point of Electroweak energies. Robert Poltis and Dejan Stojkovic http://prl.aps.org/abstract/PRL/v105/i16/e161301...

1. Astronomers on Earth observe a feature at 442 nm in the spectrum of a distant quasar. However, it is known that this feature corresponds to 581 nm in the rest frame of the quasar. Calculate the speed of the quasar. Enter your answer as a fraction of the speed of light, positive if the quasar...

people say that light emitted by quasar states that it is moving away from us? why? is it related to doppler effect? if so please explain.

If Astronomers stated that they had using the Hubble telescope found a remote island on the Earth with 1000 meter tall Homo sapiens we would based on scientific knowledge and logic concerning the biological limits of animal structure (any land based animal that moves on the surface of the earth)...

can anyone explain quasar feedback.. having some trouble.

I hear that large telescopes can resolve the Andromeda galaxy into individual stars. Is it possible to do the same for galaxies outside our local group? Also, have we observed any stars which sit in deep inter-galactic space, far from any galaxies?

Homework Statement If a quasar varies on a time scale of four months, how does the maximum size of the emitting region compare with the Schwarzschild radius for a 109 MSun black hole? Homework Equations The Attempt at a Solution Calculating the S radius of the black hole is...

A non-technical explanation for "FTL" quasar motions I was trying to think of an accurate but non-technical explanation for quasar motions that seem to be faster than light, and I came up with one. A have a friend in Atlanta and he sends me a book via UPS. That book takes three days to get...

The https://www.physicsforums.com/showthread.php?t=282116" in the Cosmology section kicks off with a reference to a late 2005 Space Telescope Science Institute (STScI) conference presentation on some recent research results on high-z quasars, from the SDSS. Much of the discussion in that...

Nice picture of quasar accretion disk---pat on back for standard cosmology in Nature The 24 July issue of Nature reports some beautiful observational work, using a polarized light filter. Actually able to SEE the hot blue accretion disk whirling around a supermassive black hole at the center of...

I've scanned some literature, but could not find a description of the mechanism that causes the "thin vertical wind"* from the accretion disk of a quasar. Can someone please explain or point me to an accessible paper? *Elvis M., 2000, Astrophysical Journal 545, 63

Does anyone know how much percentage of the total redshift of a quasar is contributed by Gravitational redshift considering light from the Quasar is emitted by heavy active galactic nuclei ? If there is a significant contribution from gravitational redshift then how will the Hubbles law hold...

What are the available theories to explain the amount of energy concentrated in quasars? And what are possible problems in those theories? I don't have any background in this, I'm just trying to ascertain whether the philosophy of technology book I'm reading is still up to date. Thanks.

What would be some arguments that show that double lobed radio galaxies and seyfert galaxies have similar energy sources? I mean i know they are powered by black holes right? are there energy arguments i can make though? thanks

[Moderator note: this thread has been created by splitting out posts related to 'the quasar "in" NGC 7319', in the https://www.physicsforums.com/showthread.php?t=113862".] Ah, the quasar that shines through a 'hole' in a galaxy! Those galaxies, they sure look 'solid', don't they? Who'd'a...

I am very disturbed by the lack of time dilation in the variability of quasar v redshift studies. http://www.arxiv.org/abs/astro-ph/0105073 Title: Time Dilation and Quasar Variability Authors: M.R.S. Hawkins The timescale of quasar variability is widely expected to show the effects of time...