Revisit relic gravitational waves based on the latest CMB observations

2018

Eur. Phys. J. C

The inflation stage has a behaviour as power law expansion like S(η) ∝ η 1+β where β constrained on the 1 + β < 0. If the inflation were preceded by a radiation era, then there would be thermal spectrum of relic gravitational waves at the time of inflation. Based on this idea we find new upper bound on β by comparison the thermal spectrum with strain sensitivity of single pulsar timing. Also we show that sensitivity curve of single pulsar timing may be hopeful tool for detection of the spectrum in usual and thermal case by using the GW150914 data.

“…By taking the reduced wavelength λ/2π = 1/H [12,13], we can obtain ν 2 1.4 × 10 −17 Hz, ν s 1.5×10 9 Hz. One can get the constant A without scalar running as follows [14] …”

Section: The Spectrum Of Gravitational Waves In Usual and Thermal Casementioning

confidence: 99%

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

2018

Eur. Phys. J. C

“…The initial amplitude of the spectrum is given by 11) where the constant A can be determined by quantum normalization [23,28] as follows:…”

Section: Appendix Amentioning

confidence: 99%

“…Therefore the amplitude of the spectrum for different ranges of wave numbers are given by [23,24,28] …”

mentioning

confidence: 99%

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

Khodagholizadeh

2017

Eur. Phys. J. C

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.

“…S(ηs) , and ζ 1 ≡ S(ηs) S(η 1 ) . With these specifications, the functions S(η) and S ′ (η)/S(η) are fully determined [1], [4].…”

Section: ) Accelerating Stagementioning

confidence: 99%

“…In the literatures [1], [2], [3] the behaviour of the inflation and reheating stages are often known as power law expansion S(η) ∝ η 1+β , S(η) ∝ η 1+βs respectively, where S(η) and η are scale factor and conformal time respectively. The parameters β and β s have constrained to 1 + β < 0, 1 + β s > 0 [1], [4]. These stages have important effect on the evolution of relic gravitational waves (RGWs).…”

Section: Introductionmentioning

confidence: 99%

Further investigation about inflation and reheating stages based on the Planck and WMAP-9

2017

Int. J. Mod. Phys. D

The potential V (φ) = λφ n is responsible for the inflation of the universe as scalar field φ oscillates quickly around some point where V (φ) has a minimum. The end of this stage has an important role on the further evolution stages of the universe. The created particles are responsible for reheating the universe at the end of this stage. The behaviour of the inflation and reheating stages are often known as power law expansion S(η) ∝ η 1+β , S(η) ∝ η 1+βs respectively. The reheating temperature (T rh ) and β s give us valuable information about the reheating stage. Recently people have studied about the behaviour of T rh based on slow-roll inflation and initial condition of quantum normalization. It is shown that there is some discrepancy on T rh due to amount of β s under the condition of slow-roll inflation and quantum normalization [6]. Therefore the author is believed in [6] that the quantum normalization may not be a good initial condition. But it seems that we can remove this discrepancy by determining the appropriate parameter β s and hence the obtained temperatures based on the calculated β s are in favour of both mentioned conditions. Then from given β s , we can calculate T rh , tensor to scalar ratio r and parameters β, n based on the Planck and WMAP-9 data. The observed results of r, β s , β and n have consistency with their constrains.Also the results of T rh are in agreement with its general range and special range based on the DECIGO and BBO detectors.