Questions tagged [quasars]
Questions about quasi-stellar radio sources, active galactic nuclei that are far away and quite old.
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Why are all quasars so far away?
Why are all quasars so far away?
If the universe is homogeneous, we should expect to have a homogeneous distribution of quasars, but all of then seem to be far away from Earth. Why is that?
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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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What happens when the quasar remnants reach Earth in 3 million years?
According to this article, during:
(during) a quasar stage in its evolution (6 million years ago) ... the Milky Way’s central black hole swallowed a huge amount of gas, creating a shock wave that has ...
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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?
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What is the mechanism through which mass is converted to thermal energy in the accretion disc of a black hole?
In the book The Cosmic Perspective, it is stated that as matter is falling into a supermassive black hole, up to $40\%$ of its mass are converted to thermal energy, making the accretion of matter ...
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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 ...
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What does "Effective radius of [CII] line is 1.4 kpc" mean?
A recent paper (A dusty compact object bridging galaxies and quasars at cosmic dawn) describes one of their results as the "Effective radius of [CII] line" (Extended Data Table 2, p38):
I ...
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How are neutrinos produced in blazar jets?
I was watching the press release about measuring neutrinos and gamma rays from a distant blazar. One of the presenters mentioned that the neutrinos are associated with very high energy protons caught ...
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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 > ...
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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 ...
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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 ...
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How bright would Sagittarius A* be from Earth if it became an Active Galactic Nucleus?
Essentially I'd like to know how bright our central black hole could appear from earth in relation to full moon brightness. Assuming maximum energy output (like when it's gobbling up an entire ...
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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 ...
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Is there a recent update on the mysterious M82 radio source reported in 2010?
The Wikipedia page on the "Cigar Galaxy" (M82) has the following summary about an "unknown object":
In April 2010, radio astronomers working at the Jodrell Bank
Observatory of the University of ...
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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 ...
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Why are the radio images of the jet of 3C 273 different?
At NASA/IPAC Extragalactic database, we can see images of the jet of matter being ejected from the quasar 3C 273. Here are a couple from the radio spectrum as examples:
My question is: why are the ...
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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 ...
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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 ...
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Sudden spikes on the light curve of a Quasar from K2 mission
I obtained the optical light curve of 3C 273 QSO from the MAST repository off the K2 mission and plotted it by making the FITS into a CSV file through Pandas dataframe and plotting the obtained ...
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On the "periodic" lightcurves of Active Galactic Nuclei
So apparently they are all lightcurves of (likely candidates) Active Galactic Nuclei and in some way or the other they all appear to be periodic:
I'd like to know the reason for this and the ...
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How to interpret this spectrum of the "new DESI Quasar at z = 6.53"; what causes the big edge at about 9150 Angstroms?
I'm not exacty sure why but Scitech Daily's Seeing Dark Energy’s True Colors: DESI Creates Largest 3D Map of the Cosmos includes the graphic and caption below.
It indicates a quasar in a Hubble image ...
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Is quasar 2M1310-1714 outside the observable universe?
This Einstein ring
Image credit: NASA / ESA / Hubble / T. Treu / Judy Schmidt
shows multiple images of the quasar 2M1310-1714. Its distance is quoted at 17 billion light years and although the age ...
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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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How much light comes from quasars in an AGN?
From what I've been able to gather, the very bright spot at the center of galaxies is produced by both the central quasar and a dense cluster of millions of stars that surround it. How much of the ...
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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 "...
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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 ...
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Why the space is so dark even there are billions of stars and many quasars emitting light [duplicate]
In our galaxy itself, there are millions of stars, and there are many more other galaxies in our local group and billions in the observable universes.
For sure they all emit a lot of light, still why ...
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Why are quasars so far away that they couldn't be optically resolved in the 1950's? [duplicate]
Wikipedia's Quasar includes the following in its introduction:
The term quasar originated as a contraction of quasi-stellar (star-like) radio source, because quasars were first identified during the ...
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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?
I just tried to read the new New York Times article Two Black Holes Colliding Not Enough? Make It Three which links to the new 25-June-2020 Physical Review Letter Graham et al. Candidate ...
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How to convert luminosity at rest frame wavelength of 1450 A to absolute magnitude at 1450 A?
How do I convert the luminosity (erg sec$^{-1}$ Hz$^{-1}$) of a quasar at a rest frame wavelength of 1450 Angstroms to absolute magnitude at the same wavelength?
I know that the bolometric ...
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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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Intergalactic Lyman-alpha absorption for high redshift quasars (Gunn-Peterson effect)
This is a follow up to a recent question on SE asking about the apparent suppression of radiation shortward of the (red-shifted) Ly-$\alpha$ line of a quasar at redshift $z=6.53$.
The general ...
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Obtaining the Light curve of a a Quasar
So, I am relatively comfortable with handling $\textit{FITS}$ files and hence I choose Python for the following operation.
The thing is that I need to analyse some Quasar light curves and hence I went ...
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Can the Hubble expansion inject energy in AGN and 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 ...
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What "external illumination" source causes the heating of a quasar's accretion disc?
In Section 3.4, UV-to-optical continuum flux ratio, Gaskell et al. (2023) Estimating reddening of the continuum and broad-line region of active galactic nuclei: the mean reddening of NGC 5548 and the ...
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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 ...
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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 ...
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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 ...
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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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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?
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What does "TON" in TON 618 stand for?
I don't think TON 618 is a random name, but rather a composition of category name and a number.
But when I tried to google it, any article about TON 618 did not contain anything about its name origin ...
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Could quasars be interior to the event horizon of a SMBH?
My question is prompted by suspicion of three current ideas in astrophysics:
GR predicts a singularity at the center of a BH without regard to QM.
quasar hyper-luminosity is caused by an acretion ...
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light emission of quasars
I'm studying Astrophysics and I have some video's from a past course. I'm currently studying the reionization of the universe. At the current point in the class, the instructor is talking about ...
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Reduced chi square value
I am currently plotting a continuum of observed data. I need to check the effectiveness of the fitted continuum with the reduced chi-square method. Ideally, should the reduced chi-square value ...
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Could life develop in a galaxy with a quasar at its centre?
Quasars are a type of Active Galactic Nucleus that inhabit the centres of some galaxies. They are among the most energetic objects known in the universe, emitting up to a thousand times the energy ...
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What enhances the capture and merge rates of pairs of small black holes orbiting around supermassive black holes?
I just tried to read the new New York Times article Two Black Holes Colliding Not Enough? Make It Three which links to the new 25-June-2020 Physical Review Letter Graham et al. Candidate ...
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How to convert spectra to log-wavelength and interpolate them into linear spacing in log-wavelength
I want to write a function that cross correlates a spectrum with a quasar template
I’d like to ask you how can I convert my flux density vs wavelength spectrum to log-wavelength. It’s not clear to me ...
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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?
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Radio SEDs for quasars
Using data from https://ned.ipac.caltech.edu/, I can get nice-looking spectral energy distributions for quasars, such as for these two:
but most of their points are in UV to IR range. I'm looking ...
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Do gravitationally bound (e.g. orbiting) objects really resist the expansion of space?
Thinking about the expansion of space, it is commonly explained that gravitationally bound objects (like galaxies and galaxy clusters) will not be affected by the expansion of space (dark energy). I ...
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