  We present a detailed discussion of the entanglement structure of vector
fields through canonical quantization. We quantize Maxwell theory in Rindler
space in Lorenz gauge, discuss the Hilbert space structure and analyze the
Unruh effect. As a warm-up, in 1+1 dimensions, we compute the spectrum and
prove that the theory is thermodynamically trivial. In d+1 dimensions, we
identify the edge sector as eigenstates of horizon electric flux or
equivalently as states representing large gauge transformations, localized on
the horizon. The edge Hilbert space is generated by inserting a generic
combination of Wilson line punctures in the edge vacuum, and the edge states
are identified as Maxwell microstates of the black hole. This construction is
repeated for Proca theory. Extensions to tensor field theories, and the link
with Chern-Simons are discussed.
