Questions tagged [quasars]
Questions about quasi-stellar radio sources, active galactic nuclei that are far away and quite old.
84 questions
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What is the difference between two types of active galaxy?
What is the difference between blazars and quasars? Is the classifcation related to the black holes at their centres? What are the relative numbers of each type and do all the known examples have ...
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Why are the QSOs from DESI so patchy?
I'm looking at DESI's QSO catalogue from the redshift catalogue. This map, showing the DR9 QSO target selection is published in Chaussidon et al. (2023), and seems to show a reasonably smooth ...
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Why would some sources in a cross-matched DESI/SDSS catalog have different spectroscopic redshifts?
I've crossmatched quasars from DESI DR9 and from SDSS DR16. When I plot the spectroscopic redshift from each of the individual catalogs for each source, I get:
Naively, I'd expect the $z_{spec}$ to ...
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How bright in the night sky would J0529-4351 (brightest quasar ever found) be if it were in our galaxy?
According to this article, the quasar (black hole) named J0529-4351 is the most luminous object in the known universe, being:
500 trillion times more luminous than the Sun
To put it in terms easier ...
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Is the code that produces the SDSS DR16Q quasar catalogue available?
I'm curious if it's available to investigate (from my question in the title), or even better, modify and re-run. See SDSS DR16Q quasar catalogue.
Not the data itself, that's in a fits file. The code ...
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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 (A quasar Milky Way six million years ago?), during:
(during) a quasar stage in its evolution (6 million years ago) ... the Milky Way’s central black hole swallowed a huge ...
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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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