energy storage
Astrophage have lots of protons contained within itself that collide. When this happens, its kinetic energy is converted into two neutrinos. Because of its super cross sectionality (basically NOTHING can get past its plasma membrane), those neutrinos don't pass through it and stay contained within the astrophage.
This also explains why its temperature is always at 96.415°C (the temperature needed for the protons to move fast enough to have enough energy to create the neutrinos). When the temperature exceeds this, the protons just move with even more kinetic energy (since temperature is just a measure of kinetic energy), creating even more neutrinos. The temperature won't stay above 96.415°C since any excess energy will be used up to produce more nutrinos. Conversely, if the temperature dips belog 96.415°, the protons won't have enough energy for neutrino production. Thus, the astrophage regulates its temperature (like warm blooded organisms) by using up existing energy to return to 96.415°C.
If anyone knows how to derive this PLEASE LMK i've been sitting here for like 5 hours trying to calculate this and derive the correct temperature arghghghghghg (there's no way weir just picked an arbitrary number right???? if all the other science stuff is so thought out)