A New Gravitational Wave Probe to the Nature of Dark Energy from the Aging of the Universe: Can Future Detectors Achieve It?

One of the most dominant energy budget of the Universe is Dark Energy, which remains enigmatic since the claim of its existence from the observation of late-time cosmic acceleration. We propose a new way of inferring this by measuring the aging of the Universe using only gravitational wave (GW) signals from coalescing binary compact objects of any masses. We show that the aging of the Universe will lead to a change in the observed chirp mass of the GW sources inferred from different stages of its coalesces by monitoring a coherent source from two far-apart GW frequencies for a few years. We show that coordinated GW detectors which can reach a relative uncertainty on chirp mass measurement of about 10^-9, can measure a tiny departure of about 2% from the dark energy equation of state parameter w_0=-1 and its variation with cosmic time by using stellar origin binary black holes up to redshift z=5 in 10 years of observation time without using any external calibrator. If the next generation of GW detectors can achieve this precision, then it can open a new window to discover the fundamental nature of dark energy.