  Periodically driven quantum many-body systems host unconventional behavior
not realized at equilibrium. Here we investigate such a setup for strongly
interacting spinless fermions on a chain, which at zero temperature and strong
interactions form a charge density wave insulator. Using unbiased numerical
matrix product state methods for time-dependent spectral functions, we find
that driving of the correlated charge-density wave insulator leads not only to
a renormalization of the excitation spectrum as predicted by an effective
Floquet Hamiltonian, but also to a cosine-like in-gap feature. This is not
obtained for a charge density wave model without interactions. A mean-field
treatment provides a partial explanation in terms of doublon excitations.
However, the full picture needs to take into account strong correlation
effects.
