Same question as Michael: if there were a point source with weird spectrum outside of any galaxy, about as bright as the average galaxy, would we reliably notice it?
I’m a bit confused if you already read my comment.
If you fake extremely high red-shift, it would likely be noticed. Radio galaxies were systematically used when looking for distant objects so if someone at the same time created very bright radio source & optical counterpart with impossibly high redshift, it would grab attention to the source, and you can signal intelligence using spectra later.
Same question as Michael: if there were a point source with weird spectrum outside of any galaxy, about as bright as the average galaxy, would we reliably notice it?
I’m a bit confused if you already read my comment.
If you fake extremely high red-shift, it would likely be noticed. Radio galaxies were systematically used when looking for distant objects so if someone at the same time created very bright radio source & optical counterpart with impossibly high redshift, it would grab attention to the source, and you can signal intelligence using spectra later.