  The chiral 2 by 2 charge order has been reported and confirmed in the kagome
superconductor RbV3Sb5, while its interplay with superconductivity remains
elusive owing to its lowest superconducting transition temperature Tc of about
0.85K among the AV3Sb5 family (A=K, Rb, Cs) that severely challenges electronic
spectroscopic probes. Here, utilizing dilution-refrigerator-based scanning
tunneling microscopy (STM) down to 30mK, we observe chiral 2 by 2 pair density
waves with residual Fermi arcs in RbV3Sb5. We find a superconducting gap of
150{\mu}eV with substantial residual in-gap states. The spatial distribution of
this gap exhibits chiral 2 by 2 modulations, signaling a chiral pair density
wave (PDW). Our quasi-particle interference imaging of the zero-energy residual
states further reveals arc-like patterns. We discuss the relation of the gap
modulations with the residual Fermi arcs under the space-momentum
correspondence between PDW and Bogoliubov Fermi states.
