Constraining Light Dark Photons from GW190517 and GW190426_152155

Ultralight dark photons predicted in several Standard Model extensions can trigger the superradiant instability around rotating black holes if their Compton wavelength is comparable to the Blackhole radius. Consequently, the angular momentum of the black hole is reduced to a value which depends upon the mass and spin of the black hole as well as the mass of the dark photon. We use the mass and spin measurements of the primary black holes in two recently observed binary black hole systems: GW190517 and GW190426_152155 to constrain dark photon mass in the ranges $1.7\times 10^{-14}{\rm\ eV}<m_{A'}<7.6\times 10^{-13}{\rm\ eV}$ and $1.3\times 10^{-13}{\rm\ eV}<m_{A'}<4.2\times 10^{-12}{\rm\ eV}$ respectively, assuming a timescale of a few million years from the time of formation of the binary black hole system to the time of their merger. We also discuss an interesting X-ray binary system, MAXI J1820_070, albeit with a relatively small value of the spin parameter.