Detection of relic gravitational waves in thermal case by using Adv.LIGO data of GW150914

Abstract

The thermal spectrum of relic gravitational waves enhances the usual spectrum. Our analysis shows that there exist some chances for detection of the thermal spectrum in addition to the usual spectrum by comparison with sensitivity of Adv.LIGO of GW150914 and detector based on the maser light. The behavior of the inflation and reheating stages are often known as power law expansion like S(η) ∝ η 1+β , S(η) ∝ η 1+β s , respectively, with constraints 1+β < 0, 1+β s > 0. The β and β s have an unique effect on the shape of the spectrum. We find some values of the β and β s by considering the mentioned comparison. As obtained results give us more information about the evolution of inflation and reheating stages.

Is pulsar timing a hopeful tool for detection of relic gravitational waves by using GW150914 data?

“…We plot h mc (ν) √ F/ν of RGWs compared to the strain sensitivity of PT based on Eqs. (6,9) in Fig. 1, respectively.…”

“…Since the polarization states are same, we consider f k (η) without the polarization index. The solution of the above equation for the different stages of the universe are given in [6]. There is another state that called 'thermal vacuum state' see [8] for more details.…”

“…There is another state that called 'thermal vacuum state' see [8] for more details. The strain amplitude of the RGWs in thermal vacuum state are as follows [6,8]:…”

“…If the inflation were preceded by a radiation era, then there would be thermal spectrum of gravitational waves at the time of inflation [3][4][5]. Based on this idea we have shown in [6] that there is some more chances for the detection of relic gravitational waves (RGWs) in usual and thermal spectrum by using the data of GW150914. On the other hand, there is an important procedure for direct detection of RGWs that called pulsar timing (PT).…”

“…But we think that the upper bound on β will modify if we use the thermal spectrum. Also the chance of detection of RGWs based on the strain sensitivity of PT will increase by using the obtained β for GW150914 [6] in usual and thermal case. Therefore the main purpose 1 Note: the upper bound on β is β ≤ −1.8 [1].…”