# Could dark matter have gamma-ray absorption lines?

1. Mar 30, 2012

### johne1618

Are there sky surveys that perform gamma-ray absorption spectroscopy?

I was wondering if dark matter might absorb gamma radiation.

I have done a simple Bohr-atom type calculation assuming a dark matter model of a bound state of a North and South magnetic monopole and found a Rydberg energy of about a MeV. I assume that the mass of the monopoles is 1 Tev; masses less than this limit have apparently been excluded by particle accelerator experiments (to a confidence of 95%). I also assume that the monopoles have the minimum magnetic charge.

Last edited: Mar 30, 2012
2. Mar 30, 2012

### johne1618

Actually I retract this calculation - I think I got my fine structure constant upside-down! And also GUT theories think the mass of the monopole is probably bigger than $10^{16}$ GeV!

3. Mar 31, 2012

### Chalnoth

It's somewhat difficult to do spectroscopy in general with gamma rays, as least where astronomy is concerned. The number counts are just too low. But I think the general expectation is that we'd see gamma rays from dark matter annihilation, but that the dark matter won't do much if any absorption.

That said, I don't think that magnetic monopoles can work as dark matter. They'd interact far too strongly with one another and normal matter.

4. Mar 31, 2012

### Chalnoth

Quite possibly!