The Constraints on the Relic Gravitational Waves By the Current and Future Observations

In this paper, by solving the inflationary flow equations, we study the constraints on the relic gravitational waves (RGW) from the observations at large scale, i.e. cosmic microwave background radiation (CMB) and large scale structure (LSS), and those at small scale, i.e. the pulsar timing, LIGO, and big bang nucleosynthesis (BBN). We find that the current constraints on the RGW from small scale are too loose to be ignored, but which from large scale is relatively tight. Under the current constraints, and considering the the damping effect of neutrino and accelerating expansion of the Universe, we also study the detection ability on RGW of the future observation projects at large scale. i.e. Planck, CMBPol, and those at small scale, i.e. advanced LIGO, LISA, ASTROD, BBO and DECIGO. We find the observations from CMB observations have larger probability to detect RGW (> 50%). But the laser interferometers have relatively smaller probability for detection: the BBO and Ultimate DECIGO project are the possible ways to detect RGW at small scale (∼ 3.48% and ∼ 26.49%), but the Advanced LIGO, LISA and ASTROD have little change to detect them. PACS numbers: 98.80.-k, 98.80.Es, 04.30.-w, 04.62.+v e-mail: [email protected]