# Tag Info

1 vote

### Do galaxies have north and south magnetic poles and can different galaxies attract each other via opposite poles?

Actually, satellite galaxies do tend to pile up along the poles of a large central galaxy. it's called the Holmberg Effect, but there are multiple effects with that name. The guy was as active as a ...
• 1,826
Accepted

### Efficient method for generating combined spectra from N-body simulation data using Python (convolution)

This is answer to my own question, same as I posted to StackOverflow. See original question for the link I completely forgot to post this answer here once I got the convolution method to work. Thanks ...
• 41

### Do galaxies have north and south magnetic poles and can different galaxies attract each other via opposite poles?

The galactic magnetic field is largely created by charged gas clouds rotating with the galaxy https://www.wtamu.edu/~cbaird/sq/mobile/2014/09/03/why-dont-galaxies-have-a-natural-magnetic-field-like-...
• 555
Accepted

### What are isophotal diameters? And how do they relate to galaxies' size?

Galaxies are intrinsically fuzzy objects that usually fade away fairly smoothly in density as you go out in radius. So there isn't really such a thing as the diameter or size. Isophotal diameters are ...
• 17.8k

### Finding the angular size of a galaxy cluster when given the RA and Dec cordinates of all the galaxies in the cluster

If the cluster is symmetric take the difference in declination between the galaxies with the highest and lowest declinations$^{*}$. This is the angular size. $*$ Assuming the cluster does not span the ...
• 157k
1 vote

### What is galaxy internal velocity anisotropy?

Isotropic means the same in all directions. If all galaxies you observe move in random directions, their velocities are isotropic. If most galaxies appear to be moving in the same direction, then the ...

### What does Colossus cosmology.sigma() return

The documentation says "rms variance", which means $\sigma$ and not $\sigma^2$. ("rms" is short for "root mean square".) I can't attest that the code returns the correct ...
• 4,760

### Reasons for extremely high number density of galaxies at low redshift

Disclaimer: not an expert on this area. However, I'm writing an answer because there's not currently one, and because the answer below works for the number density of supernovae with redshift and I ...
• 4,719
1 vote
Accepted

• 36