LH1 is easily visible because of the space-time distortion it causes in the image of the distant galaxy behind
One of the largest artificial structures in the Visible Universe was first seen by the Argus Array in 6110 AT. Leo Hyperobject 1 is 339 million light years from the Milky Way, in Abell 1369, the Leo Supercluster. This object was first detected because of the Einstein Rings surrounding it; the sphere is silhouetted against the distant galaxy DDF 155A09A091 which has a redshift of z =10.5 and a light-travel-time distance of 13.2 billion light years.
LH1 has an apparent mass twice as great as the Milky Way and a diameter of 1.2 light years. This object seems to have been constructed using almost all the mass in the local galaxy, and less than a thousand stars remain in its immediate vicinity, each orbiting the structure at high velocities. Some of these stars have habitable planets. The outer surface of LH1 is a featureless radiator, with several billion entry- and exit- ports; craft have been observed to enter the structure on occasion, but this traffic has diminished in the last two millennia to almost zero. Many observers speculate that this construct contains a culture that is becoming increasingly isolated from the rest of the universe.
Possible internal structures of the Leo Hyperobject
Such a large mass located within a space little more than a light year across would quickly self-gravitate into a hypermassive black hole, emitting stupendous amounts of energy in the process. So this object must be self-supporting, probably using dynamic orbital ring technology.
The outer shell of this object radiates a significant amount of waste heat, suggesting that there is substantial activity within. One possible model for the structure inside is that of a so-called 'supraself'; a series of millions of supramundane shells that are supported by dynamic orbital rings, centred around the centre of gravity of this object. Such a 'supraself' could potentially have a habitable surface area around 10e23 times as large as the Earth.
However the effective gravity on the outermost surface is only 0.2 gees; if the hypothetical internal shells are evenly distributed, then they will also have lower gravity than Earth. It is possible that the internal shells are concentrated more closely together, and the outermost shell is located further away to increase its effectiveness as a radiator. Note that the mass of this object is still very large, and causes significant time-dilation within its structure - the centre experiences a time-rate hundreds of times slower than the surface.
If the supraself structure contains both computronium and habitable levels, it is possible that the waste heat of processing can be used by the habitable levels to support their ecological systems and other activities. Habitable levels and processing levels may alternate for some fraction of the internal structure, allowing the object to support vast numbers of xenosophonts of a range of toposophic types.
Assuming that this construct was created from at least one large galaxy, it is likely that the supermassive black hole at the centre of that galaxy was included at its centre; the hyperobject may have started out as a suprashell around that black hole. If so, the amount of mass available for habitation and/or processing is diminished somewhat, but probably by an insignificant amount. Alternately the structure could have been constructed at a distance from the central black hole, although this object should be detectable nearby (no such object has been observed).
A large hyperobject of this kind is visible for many millions of light years around, and could attract the attentions of unfriendly xenosophonts. It is possible that the entities who created this object have taken steps to ensure that the volume of space around it is secure; perhaps by memetic influence spread during the many millions, or billions, of years it took to create the shell. Or perhaps any alien species that might pose a threat have been eliminated, possibly using a coherent beam of energy emitted by the outermost shell of the structure. If such a beam were directed against potential enemies in a nearby galaxy, it would take several million years for the beam to arrive; by which time the potential enemies may have become naturally extinct, or have developed an advanced civilisation. If so, even a Nicoll-Dyson beam from an emitter a light-year across might not be enough to ensure destruction.
It seems likely that such an advanced civilisation might attack, possibly using metric weapons that could damage even a vast structure like this. The strategy of converting an entire galaxy into a single hyperobject seems risky, and this may be the reason that very few other examples have been observed (all of which are smaller than this one). Indeed, the metal-rich debris found surrounding the isolated hypermassive black hole HB144 in Coma may be the remnants of a galactic suprashell that was destroyed during construction, or after completion.