  We explore the potential of detecting parity violation in primordial vector
fossils using late-time galaxy spins. Utilizing $N$-body simulations, we use
halo spins as a reliable proxy for galaxy spins to investigate how effectively
such primordial vectorial parity asymmetry remains in galaxy spins at low
redshifts. We develop a novel approach to generate initial conditions with
substantial parity asymmetry, while maintaining the initial matter power
spectrum unchanged. From the parity broken initial condition and halos evolved
from it, we construct the initial spin and halo spin fields, respectively.
Focusing on the helicity of these vector fields, we detect substantial
asymmetry in the initial spin field as a consequence of parity violation in the
primordial vector fossil. In addition, we discover that over $50\%$ of the
primordial asymmetry in the initial spin field remains in the late-time halo
spin field on a range of scales. Given the tight correlation between halo spins
and observable galaxy spins, we expect to detect the current amplitude of
vectorial parity asymmetry potentially up to $16\sigma$-level in observation,
when utilizing galaxy samples from DESI BGS. Our findings demonstrate that the
primordial imprints of vectorial parity violation persist through non-linear
gravitational evolution, highlighting the reliability of galaxy spin as a
sensitive probe for testing the vectorial parity-invariance in the early
Universe.
