How to calculate how many 'overlaps' to expect, given ...?
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by
JeanTate
Spiral galaxies with double-lobe radio emission, which extends well beyond the optical boundary of the galaxy, are extremely rare; Keel+ 2006 reports one of the very few, discovered a decade or so earlier.
"Double-lobe" radio structures (doublelobes, for short) are pretty common, as are spiral galaxies. If you have a spectrum of a galaxy, you can (almost always) estimate its redshift, and so its distance; as far as I know, this is not possible for doublelobes.
Assume the distribution of doublelobes across the sky is independent of the distribution of spiral galaxies. How would you go about calculating how many 'overlaps' to expect?
At first glance this might seem fairly straight-forward, at least in principle; on thinking about it some more, I conclude that it's anything but. Of course, I could well be quite wrong! What do you think?
Some clarifications/elaborations:
-> the distribution of spirals could be either 'on the sky' or in 3D
-> what counts as an 'overlap' is, obviously, a key factor; assume that the spiral must be 'between' the two lobes (so, for example, FIRSTJ154336.1+110527/SDSS J154336.07+110512.9 are not an overlap; some details here)
-> if it helps, assume you have only the FIRST and SDSS DR10 data
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