Question on the Argus Array

[Worldtree]

Hi Merkudul ! welcome

A few of these articles about civilizations in the local group and beyond give some idea for the resolution of the Argus Array https://www.orionsarm.com/eg-article/45f97a51dbf24

https://www.orionsarm.com/eg-topic/5bab622ee8c16
The Golden Tower builders in the Andromeda galaxy
https://www.orionsarm.com/eg-article/46f96880b0a26

The Once and For All (an article still in development)  comes close to a "very impressive thing seen at billions of light years away" 
https://www.orionsarm.com/forum/showthre...268&page=8

But these threads gives some numbers about the limits of the Argus Array 
https://www.orionsarm.com/forum/showthre...rgus+array
https://www.orionsarm.com/forum/showthre...rgus+Array

The minimum theoretical diameter for an object to be resolved by an optical sensor is (1.22*[wavelength/diameter])/distance. Wavelength is the frequency of light your detecting, diameter is the diameter of the sensor (or sensor array if using an interferometer), distance is distance to the object. Given this observing at a wavelength of 5e-7m (within the visual spectrum), taking the Argus array to be 1e19m wide (approximately 1000ly) and the distance of 3.26e25m (a gigaparsec) the smallest theoretical diameter of an object to be resolved is 2 meters.

There are many caveats to this however. Interstellar dust will scatter the light, the time to resolve will be enormously long (potentially millions or more years) given the few photons caught, the object may be exceedingly dark/cold exacerbating the latter, relative motion and inflation will distort wavelength etc.

One of the more unusual consequences of an expanding universe is that the universe was a lot smaller when it was younger. This means that the galaxies that we now see as being at the far edge of the observable universe were only a few tens, or hundreds, of millions of light years away when they emitted the light which we now see. The result of this is that galaxies, nebulae, and individual stars look much larger than we might expect given their distance. 
https://en.wikipedia.org/wiki/Angular_di...over_point

On the other hand, the light we receive from these objects is very redshifted, so the number of photons we receive is smaller, and contain less energy, than the light we receive from nearby objects of a similar nature. Once again, the main limitation on the power of the Argus Array is the lack of light we can obtain to build a picture; resolution is less of a problem.
For instance the most distant galaxy yet seen by the James Webb telescope has a redshift of about z=20. and appears the same size as a galaxy 500 million light years away,

even though the light-travel distance is more than 13 billion light years.