Massive systems held together by gravitational attraction, consisting of stellar associations, star systems, star clusters and types of interstellar clouds, stellar remnants, gasses, cosmic dust and an important but not yet completely understood component called dark matter.

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Relation between isophotal radius and virial radius in spiral galaxies?

Is there any (proposed) relation between the B-band isophotal radius of a spiral galaxy and its virial radius (r_200)? If you know of such a relation, please post a reference paper.
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39 views

Need help on Springel model for galaxy dynamics

I would like to have help about the response of the dark matter profile in the Springel galaxy dynamics model ( from the paper Tidal tails in CDM cosmologies(NB: Arxiv pre-print)) Here's the part of ...
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41 views

Dimension of galaxy filaments

Galaxy filaments are amongst the largest known cosmic structures in the universe. They [...] form the boundaries between large voids in the universe. As their name suggests filaments are ...
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253 views

Why do galaxies collide? Reconciling dark energy and an expanding universe with the fact that some galaxies are on a collision course

My layman understanding of cosmology is: galaxies are uniformly (more or less) spread throughout the universe, per the Big Bang and the fact that in a central explosion, all dispersed points are ...
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83 views

Can one model a spiral galaxy with a similar manifold to one for a whirlpool?

My question is more of a phenomenological question than literal, since the forces involved are very different. When one looks at the distortions (or wrinkles or whatever you wish to call them) in the ...
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21 views

Velocity dispersion of galaxies

I couldn't find on web how can I get the velocity dispersion and velocity maps of galaxies from the 3D data cube I get from integral field spectrograph.
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154 views

Galaxies and projected radius vs arcmins

I have two sets of data (globular clusters), one for the Andromeda Galaxy and one for the Milky Way. I want to compare the distribution of globular clusters between the two galaxies according to ...
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16 views

Synthesising types of galaxies using various stellar spectra

I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy (considering the arms and the bulge separately and adding them) using stellar spectra which I ...
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43 views

What's so special about velocity dispersion relations in astrophysics (M-sigma relation, Tully-Fisher, etc)?

I'm confused. Velocity dispersion of stars is measured by Doppler broadening, and through virial theorem that provides information about enclosed masses of galaxy bulges, galaxies, etc, as explained, ...
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77 views

What is the equation for Lin-Shu density wave theory?

Lin-Shu density wave theory is a (very good) theory to explain the spiral arm structure of spiral galaxies. Where can I find the equations that underlie this theory? I've seen its computer ...