Questions tagged [quasars]
Questions about quasi-stellar radio sources, active galactic nuclei that are far away and quite old.
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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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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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Trying to understand how to properly implement this equation to a healpix map
So i am working on reproducing a paper (Secrest, N. J., von Hausegger, S., Rameez, M., Mohayaee, R., Sarkar, S., & Colin, J. (2021). A test of the cosmological principle with quasars. The ...
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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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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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Are there any experiments or observations indicating that the Hubble flow can influence AGNs, quasars and galactic winds (outflows)?
Galactic winds (or outflows) are produced by AGNs (Active Galactic Nuclei), quasars, supernovas...etc which basically eject matter usually in form of waves or spheres, sometimes even arriving to the ...
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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 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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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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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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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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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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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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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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Obtaining the Flux-Time plot for a Quasar
As a follow up question to Obtaining the Light curve of a a Quasar, I wish to know how to obtain a Light curve for a quasar observation like this data set over here.
Is there an archival repository ...
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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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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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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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How can I find more information on a certain galaxy when NED isn't helping?
The paper High Frequency Peakers: Young radio sources or flaring blazars? by S.Tinti et.al. lists some nice radio-wavelength SEDs, like these for instance:
When looking for more photometric info on a ...
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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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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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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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Can Quasars generate Heavy Elements?
Pretty sure Quasars were involved in increasing Galactic metallicity but is there evidence of quasar AGN's generating heavy elements, such as radioactive ones and shooting them across the universe in ...
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How does hawking radiation work without virtual particles?
How does hawking radiation work without the existence for virtual particles? I read that certain quantum fields are distorted when a black hole forms on top of them. But what fields specifically? If ...
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How do accretion disks around black holes evaporate via winds?
I'm curious as to how accretion disks around black holes evaporate. I've heard winds play a crucial role in this. But what winds specifically and how do they form? Is it a stellar wind of sorts? If so ...
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In the 1950's how were radio-astrometric positions with portable dishes so precise they could be assigned to their dim optical counterparts (Quasars)?
In my question Why are quasars so far away that they couldn't be optically resolved in the 1950's? I included the following short paragraph, but then added strikethrough to the second sentence ...
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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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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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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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How to model blazar light curves
I have SED data spanning over a couple of days and I'm able to find the parameters of the SED (R, B, break energy,...) using least squares method. My question is how to model light curves (with t_acc, ...
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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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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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Absorption line in quasar spectrum
I have quasar spectrum which includes emission and absorption lines. I need to find absorption lines in between 2 wavelength. How can I do it with coding?
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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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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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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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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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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 ...
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What compounds are present in 3C273?
Anyone know if we have any chemical reactions occuring in this quasar?
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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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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 ...
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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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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 ...
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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 ...
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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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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 ...
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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 ...
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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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