Are galaxies of antimatter identifiable?

[Leo Klem]

12 August 2009

My question relates to the search for antimatter in the cosmic space. As far as many laymen know, the composition of the material ingredients of galaxies is detected through spectroscopic analysis (i.e. through the analysis of the electromagnetic waves emitted).
Considering that antimatter consists of leptons and hadrons that substantially differ from the corresponding components of the ordinary matter only because of the respective electrical charges, is there any special reason that makes spectroscopic methods distinguish galaxies of matter from galaxies of antimatter?
In simpler words, can galaxies consisting of atoms of antimatter (in electrical equilibrium) be optically distinguished from galaxies made of ordinary matter?

 

[negitron]

No, because a photon is its own antiparticle. In other words, even if antimatter emits antiphotons, we can't tell the difference because an antiphoton IS a photon just like the ones we know and love.

 

[Nabeshin]

This thread from a few months ago seems relevant:

https://www.physicsforums.com/showthread.php?t=314184