Questions tagged [galaxy-cluster]
Questions regarding gravitationally bound systems of hundreds to thousands of galaxies as well as interactions between such systems.
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Is there a better explanation of this picture showing the very distant star "Earendel"?
"Close-up of the tiny region where Earendel happened to fall right on top of the narrow line where the magnification increases by (tens of) thousands of times. A cluster of many stars is seen ...
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What is the ultimate fate of a cluster of galaxies?
We're fairly aware clusters of galaxies drift apart due to space expansion, which will drive them out of each other's cosmic event horizon eventually, leaving them separate, alone, each a single "body"...
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How are Galaxy Super Clusters Generated
I have seen pictures of clusters of galaxies, usually used in regards to theories of dark matter and galaxy formations. One of the most famous ones has the perceived shape of a stick-figure. If I am ...
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Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection
I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection
of the right ascension and declination the galaxies relate to the center of ...
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When will the Milky Way "arrive" at the Great Attractor, and what all happen then?
The Great Attractor is described as a location to towards which the Milky Way, along with all other galaxies in the Laniakea Supercluster are moving. How long will it take for the Milky Way to "arrive"...
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To what extent do the spin of smaller celestial bodies reflect the spin of the larger system’s of which they are a part?
One can ask whether two objects are spinning in the same direction or not. For example, the Sun, Earth, Luna, most of our solar planets (except Venus and Uranus), and the planets’ satellites all spin ...
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Local neighbourhood and Superclusters
Recently, I watched a YouTube video on Limits of Humanity, by famous Youtube channel Kurzgesagt. It talked about the local neighbourhood, and it is the only group of galaxies which are gravitationally ...
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Is the Hubble Ultra-Deep Field image representative of the entire sky?
The Hubble ultra-deep field image is a photograph of an area of sky equivalent to a 1mm x 1mm piece of paper held a metre away from the eye (one thirteen millionth of the entire sky). It contains an ...
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Is there a paper on galaxy mergers in clusters of galaxies?
I'm looking for something to cite about galaxy mergers in clusters of galaxies.
I need numbers on the frequency of mergers in the outer parts of galaxy clusters vs. the cluster center. In the center ...
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How do astronomers know that distant galaxies aren't actually nearby star clusters?
When reading about the recent release of data from the Dark Energy Survey, and the 'pictures' of well over 200 million distant galaxies, I got to wondering:
How can they know that a small, faint, ...
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Does the Milky Way belong to a Galaxy cluster
I know that the Milky Way is a member of the Local Group and the Virgo Supercluster / Laniakea Supercluster. However, I can't seem to find any information about the Galaxy cluster we belong to.
Does ...
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Would gravitational waves be subject to external gravitational perturbations?
Given that the gravitational wave detected by LIGO was a very weak echo of a very distant event, could it have been "deviated" and distorted on its way here by a sufficiently massive black hole in ...
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Why does the concentration-mass relation of galaxy clusters have a negative slope?
As reported in some recent observational works works (ref. Merten et al. 2015) the concentration-mass relation of galaxy clusters has a negative slope. This means that at a fixed redshift, haloes with ...
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How many galaxies are currently merging?
On the homepage of the galaxies research group at CfA SAO, it states, "Astronomers discovered that as many as 25% of galaxies are currently merging with others." They do not provide a ...
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Why does the Bullet Cluster have many names?
On Wikipedia, there are two names to call the Bullet Cluster, '1E 0657-56' and '1E 0657-558'.
Furthermore, even on the NASA Hubble Space Telescope site, they call it '1E 0657-556'.
Why is the bullet ...
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Fingers of God effect for galaxy clusters
Galaxies that reside in galaxy clusters are know to have peculiar velocities that cause the Fingers of God effect.
But what about galaxy clusters themselves?
Do they also have peculiar velocites ...
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What accounts into calculating the Hubble constant?
From my understanding, the Hubble constant $H_0$ calculates from observed redshifts $z$ of distant galaxys against their proper distance $D$. The current value appears to be 67.80(77) $\frac{km}{s}Mpc^...
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What distance is considered 'close' for the 9th nearest neighbor of a galaxy?
I am currently working on determining the nth nearest neighbors of a large survey of galaxies. I am not an astronomer by trade, so I am unsure of interpreting some of my results. I have discovered for ...
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Generating random galaxy catalogs for correlation functions
The galaxy correlation function, when computed directly from a galaxy catalog, relies on computing a randomly generated counterpart catalog.
When dealing with a simulated galaxy mock-catalog, where ...
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Interpretation and understanding of the relation for the photometric redshift in a given bin
In the context of photometric probe of surveys (like LSST), I need to understand the relation I have to use for photometric bins.
Considering $p_{ph}(z_p|z)$ the probability to measure a photometric ...
user16492
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How to determine the mass of a galaxy?
I am having a slight disagreement with my professor.
We can measure the mass of a distant star cluster from:
A.Its color
B.Its radius
C.Its metallicity
D.Smearing of lines in its total spectrum
My ...
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Which galaxy is closest to the center of the KBC void?
I was reading up on Bootes void and came across this list of the largest voids in the visible universe, and apparently the one we're in, the KBC void, is not only the biggest, but damned-near ...
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Temperature of the intracluster medium (ICM)
I've read once in an article that the temperature of the medium within galaxy clusters (the intracluster medium or ICM) is extremely high.
What does that temperature really mean? Particle velocity?
...
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What is the distance of the closeset galaxy outside our local group and what is its name?
The Milky Way is 2.5 million light years from Andromeda and the size of the Local Group has a diameter of approxmiately 10 million light years across.
What is the distance from this Local Group to the ...
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Why does the first measurements of the thermal Sunyaev-Zel’dovich effect from ALMA show a temperature decrease and not an increase at the cluster?
Seeing the phrase a fully functional Stewart Platform I Wikipediad it and that article shows the AMiBA a CMB interferometer mounted on a hexapod (shown below).
Wikipedia's Sunyaev–Zeldovich effect; ...
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Why does a right-handed circular polarized wave get lagged when going through ionized plasma?
I have a question related to Faraday rotation. In Abigail Polin's Faraday rotation video I have seen that a linearly polarized wave can be decomposed in a left-handed circular wave and a right-handed ...
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Do other supercluster like Laniakea also get pulled by the Great Attractor?
I'm not sure, whether there is any other observable super cluster like our local one, Laniakea, and if they do exists, do they also get pulled by the Great Attractor?
I am a little confused about ...
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what is the current explanation for the formation of cosmic voids?
Why aren't galaxies distributed evenly in space, but instead form those sponge-like structures, with huge voids between filaments?
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Are there small voids of 10 - 20 megaparsecs also within, and not only between superclusters?
I sincerely apologize if this question is stupid, however after all the articles I read so far, I could not confirm this assumption, which I think is actually a fact, but I'm not completely confident.
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Are high-speed galactic collisions survivable?
This is a hypothetical question, but it really is meant as a vivid way of asking about the affects of high-speed galactic collisions. The November 27 APOD showed the Cheshire Cat galaxy group, and the ...
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Is the local group bound to the Virgo cluster?
The Virgo Cluster is currently red-shifted by 0.003 according to Wikipedia; this indicates that the cluster is expanding. Will the cluster's enormous gravity eventually "win" and pull the ...
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How are shockwaves used to study magnetic fields of merging galaxy clusters?
Recently i read an article about how a shockwave 60 times larger than milky way galaxy is generated.When these shockwaves interacts with magnetic field, radio waves are emitted. I wanted to know how ...
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Recent research regarding if the local group of galaxies will remain bound to the Virgo Cluster?
The question of if the local group of galaxies will remain bound to the Virgo Cluster has been asked before (Is the local group bound to the Virgo cluster?). I am wondering if there is any more recent ...
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Cross-correlations between Lagrange and Fourier synthesis
In the context of forecast for large surveys, I have to make cross-correlations between 2D (with angular coordinates of Lagrange transformation for GC photometric and Weak Lensing) and 3D (Fourier ...
user16492
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Why is this Einstein ring pink?
I'm having a hard time understanding this image in the CNN News item This glowing ring of light is from a distant galaxy.
The caption (from this version of the article) says:
This image shows ...
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Are 3D coordinate data from Sloan DSS-III available & easily accessible to non-pros?
Of course the newly announced SDSS-III data and maps from the Sloan Digital Sky Survey with 1.2 million objects, along with all previous data sets are openly available, and I'm sure there are many ...
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Is there a consistent missing mass ratio for Galaxy Clusters?
The Coma Cluster is what famously lead Fritz Zwicky to the conclusion that Dark Matter exists. As the velocities of the galaxies within the cluster were too fast for them to remain within orbit of ...
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Why is the dark matter component of MOND important in central regions?
A lot of papers say that even the theory of MOND requires the existence of dark matter, particularly in the central regions. However this is a bit counterintuitive to me considering that rotation ...
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Converting equatorial coordinates to Cartesian coordinates for extragalactic distances
I'm trying to search for galaxy clusters with the friends-of-friends (FoF) algorithm. I have the equatorial coordinates ($\alpha, \delta$) and redshifts ($0.5<z<2.5$) of galaxies that I wish to ...
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Deep-CEE I data
I was reading Deep-CEE I: Fishing for Galaxy Clusters with Deep Neural Nets and I couldn't find the dataset.
Could someone provide me with the links related to this?
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What's so interesting about Coma-type galaxy clusters?
When the dynamical mass of a proto-cluster of galaxies is ~(1-2)x1014 Msolar, the proto-cluster is expected to evolve into a coma-type cluster.
In almost every paper I read about the confirmation of ...
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Does the Abell 1689 supercluster have angular momentum?
The Abell 1689 is a large group of galaxies, containing a lot of elliptical galaxies :
https://en.wikipedia.org/wiki/Abell_1689
Usually, an elliptical galaxy don't have large angular momentum around ...
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Difference in the baryon acoustic oscillation measurements
I understand from this Wikipedia page about baryon acoustic oscillations (BAOs). I can also see that BAO measurements were first detected using luminous red galaxy samples.
Now, many papers use ...
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What percentage of galaxies are isolated galaxies and what percentage are members of a cluster?
Some galaxies, such as NGC821 are classified as "isolated galaxies", others form parts of distinct groups or clusters (relevant link) Although isolated galaxies may be accompanied by small ...
user50623
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Deviations of conservation laws in the context of cosmological evolution?
If energy is "not conserved" in General Relativity (or at least, it is difficult to define it) in the context of an accelerating expanding spacetime (like it happens in our Universe), are ...
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Getting XYZ coordinates of Luminous Red Galaxies catalogue
So I want to get the XYZ (rectangular/Cartesian) coordinates of the LRG (luminous red galaxies) catalog. The catalog is available for download from here: https://data.sdss.org/sas/dr16/eboss/lss/...
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Total number density of galaxies and problematic expression in practise
This post comes from physics exchange forum, I have transfered it here, maybe I will be luckier since I have not received answers on the other forum.
Here is the issue :
I am asked to give the ...
user16492
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Energy conservation in Barnes-Hut algorithm [closed]
I wrote a code that follows the Barnes-Hut algorithm for gravitational dynamics. Everything looks pretty good, except that when I plot the total energy $$E_{tot}\equiv E_k+E_u=const$$ I get this ...
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H-alpha velocity fields of spirals falling into a cluster
What kind of impact would you expect ram pressure stripping / tidal interactions / harassment / interactions with the cluster potential (etc!) to have on the h-alpha velocity fields of infalling ...
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Is it possible for galaxy clusters to interact?
Galaxies commonly interact and collide with other galaxies. Is it possible that clusters of galaxies similarly interact and collide? Have people tried to study this phenomenon previously? I couldn't ...
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