Observable Spectra of Induced Gravitational Waves from Inflation

By Laila Alabidi, K. Kohri, Misao Sasaki, Y. Sendouda. 2012

148 citations recorded by the source corpus.

Measuring the primordial power spectrum on small scales is a powerful tool in inflation model building, yet constraints from Cosmic Microwave Background measurements alone are insufficient to place bounds stringent enough to be appreciably effective. For the very small scale spectrum, those which subtend angles of less than 0.3 degrees on the sky, an upper bound can be extracted from the astrophysical constraints on the possible production of primordial black holes in the early universe. A recently discovered observational by-product of an enhanced power spectrum on small scales, induced gravitational waves, have been shown to be within the range of proposed space based gravitational wave detectors; such as NASA's LISA and BBO detectors, and the Japanese DECIGO detector. In this paper we explore the impact such a detection would have on models of inflation known to lead to an enhanced power spectrum on small scales, namely the Hilltop-type and running mass models. We find that the Hilltop-type model can produce observable induced gravitational waves within the range of BBO and DECIGO for integral and fractional powers of the potential within a reasonable number of e−folds. We also find that the running mass model can produce a spectrum within the range of these detectors, but require that inflation terminates after an unreasonably small number of e−folds. Finally, we argue that if the thermal history of the Universe were to accomodate such a small number of e−folds the Running Mass Model can produce Primordial Black Holes within a mass range compatible with Dark Matter, i.e. within a mass range 1020gMBH1027g.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/dd878708f48b902e0bf01a555b38fe61f7a1560f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. K. Kohri
2. T. Terada
3. T. Nakama
4. T. Harada
5. Keisuke Inomata
6. Chul-Moon Yoo
7. K. Nakao
8. S. Jhingan

In Statistical and Nonlinear Physics

1. T. Scully
2. Evangelos Sfakianakis
3. Peter Adshead
4. K. Kohri
5. T. Terada
6. John T. Giblin Jr.

Citations in the corpus

• Solar-mass primordial black holes explain NANOGrav hint of gravitational waves (2020, background): “It is interesting that we can indirectly probe physics of inflation by probing the primordial scalar (curvature/density) perturbations inferred from the second-order GWs and PBH abundances [17–22].”
• Gauge-preheating and the end of axion inflation (2015, background): “These large amplitude density fluctuations can produce primordial black-holes [83–85] and ensuring that they are not overproduced requires that ξCMB .”
• Semianalytic calculation of gravitational wave spectrum nonlinearly induced from primordial curvature perturbations (2018, background): “[24], but we find it shows the wrong behavior for the contribution from the long-wavelength modes of the density perturbations.”
• PRIMORDIAL BLACK HOLE FORMATION IN THE MATTER-DOMINATED PHASE OF THE UNIVERSE (2016, background): “More recently, Alabidi & Kohri (2009) and Alabidi et al. (2012, 2013) showed that in the socalled hill-top-type inflation scenario, density perturbations of large amplitude can arise on small scales and lead to an enhanced formation of primordial black holes in an effectively matterdominated phase…”
• Gravitational waves induced by scalar perturbations during a gradual transition from an early matter era to the radiation era (2019, background): “In addition, there can also be cosmological origins such as vacuum quantum fluctuations during inflation, cosmic strings and scalar perturbations at the second order [2–6] (see also Ref.”