What primarily supports a white dwarf remnant against gravity after stellar life ends?

Quantum mechanical pressure resisting gravity

A white dwarf forms as the dense, hot remnant core left behind by Sun-like stars after they have exhausted their fuel and gently shed their outer layers. Crucially, a white dwarf no longer generates energy through sustained nuclear fusion in its core; therefore, it cannot rely on thermal or radiation pressure to support itself against its own immense gravitational pull. Instead, its long existence spanning cosmic timescales is maintained by a purely quantum mechanical effect. This force, known as electron degeneracy pressure, acts as a stiff, inherent resistance to further compression, effectively balancing the relentless inward force of gravity without the need for ongoing thermal energy generation.