Black Hole Forge
The Black Hole Forge is the source of all the Nomai warp cores found around the solar system, and is found suspended below the Hanging City, just above the black hole at the planet's center. The forge itself can be raised and lowered from the control room on the first level of the Hanging City, and accessed via the uppermost level, which itself can only be accessed via the warp portal on Ash Twin. The Black Hole Forge was used to craft the Advanced Warp Core, which powers the Ash Twin Project.
Whilst the Black Hole Forge can be accessed from the uppermost level, the pathway is actual broken and you will find yourself unable to get to it. You must first raise the Black Hole Forge, then fly to the Ash Twin and use the corresponding Ash Twin Tower to warp to the Black Hole Forge.