Galaxy cluster Definition and 20 Threads

According to some papers I've found [1], [2] expanding voids can be found inside clouds of denser materials that can cause them to eventually collapse. I have a question about this: Overdensities generally expand up to a given turnaround radius and then collapse. However, as the elements in the...

CMB photons can be affected by the expansion of the universe through the linear integrated Sachs-Wolfe effect (ISW) [1] and the non-linear ISW effect or also called Rees-Sciama effect [1]. In particular, according to the ISW effect, the photons crossing superclusters would leave them having a...

Dark Energy puts a constrain on the size of overdensities (like clusters and superclusters of galaxies) and their growth. A higher Dark Energy density would reduce the radius of the zone where matter would be gravitationally bound, because more Dark Energy density would mean that objects would...

I have a question about this work called "Dark energy and key physical parameters of clusters of galaxies"*There, towards the end, the authors talk about the isothermal velocities and tempreature parameters of the gas and particles circulating between galaxies in clusters. In particular they...

Concerning cosmological structures (like galaxies, clusters of galaxies, gas bodies, superclusters...etc) if the elements that make them are close enough they will be attracted towards each other by gravity. Contrarily, if they are sufficiently far apart they will get further away following the...

If energy is "not conserved" in General Relativity (or at least, it is difficult to define it) in the context of an expanding accelerating spacetime (like it happens in our Universe), are there any observations of deviations from the strict conservation laws in the evolution and formation of...

I found an old article (https://journals.aps.org/pr/abstract/10.1103/PhysRev.137.B1379) which talks about conservation of energy in an expanding space. Apparently, the author found that energy is conserved at local scales (like the motion of planets in our solar system) as one would expect, but...

I assume we can work it out from X-ray emission detections, such as shown with the famous bullet cluster images.

I am trying to follow a calculation from the book of William C. Saslaw, The Distribution of the Galaxies: Gravitational Clustering in Cosmology. The calculation is shown on the pages following page 122 in chapter 14 where the author talks about the Correlation function. I am able to reproduce...

<Moderator's note: Moved from a technical forum and thus no template.> Suppose that all stars in this galaxy were born in a single major-merger burst event about 10 Gyr ago. From this original burst, I want to compute the fraction of stellar mass still surviving as stars in the main sequence ...

Homework Statement An estimate of the mass of the Coma cluster can be made from the velocity of the galaxies relative to the centre of mass of the cluster; the velocities are around 2000 km s-1. The stars that form the cluster have been together for a long time. Show that a simple model will...

Hello! I watched a video on the Youtube channel Kurzgesagt titled How far can we go? Limits of humanity The video attempts to explain why we may be limited to our local galaxy group even with science fiction technologies. During a part of the video (starting at 2:26), they try to explain how...

Homework Statement I want to calculate/estimate the average photon energy from a galaxy cluster incident on the mirror of a X ray telescope (Chandra to be specific) . The cluster has redshift z and at constant uniform temperature T Homework Equations Specific Intensity of thermal...

I found this: http://adsabs.harvard.edu/abs/1992A&A...259L..31B document that describes how the X-Ray emissions from galaxy clusters are used to calculate the mass of the cluster. I'm unable to follow the steps to calculating the gas mass. Specifically, in section (2) there is a formula for...

If objects in the universe are built hierarchically, wouldn't one expect a Galaxy Cluster that is roughly spherical to follow the same profile as an elliptical galaxy?

Astronomers find galaxy cluster with bursting heart An international team of astronomers has discovered a gargantuan galaxy cluster with a core bursting with new stars - an incredibly rare find. The discovery, made with the help of the NASA/ESA Hubble Space Telescope, is the first to show that...

I have a modification to MOND that appears to work much better than 'Standard' MOND at the galactic scale. I want to test this model now on larger structures. Does anyone know where I can find kinematic data on galaxy clusters, preferably some 'gold' standard that people have been examining for...

Below are two URLs to Hubble telescope photos of galaxy clusters. I would like to know if every single white or colored splotch in these photos is a galaxy, or do single/individual stars/suns manage to get mixed in there? Thank you for your time...

I saw this article and wondered if there is cause for concern? It does seem rather large and well defined so soon after the BB. Massive galaxy cluster could upend theory of universe evolution...

I'm doing an undergraduate research project this term on some modified theories of gravity, and I need some mass/density profiles. Does anyone know any papers that give mass profiles of galaxy clusters determined predominantly through gravitational lensing measurements? The model I'm working...