Flattened bispectrum of the scalar-induced gravitational waves
Abstract Recent pulsar timing array collaborations have reported evidence of the stochastic gravitational wave background. The gravitational waves induced by primordial curvature perturbations, referred to as scalar-induced gravitational waves (SIGWs), could potentially be the physical origins of th...
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SpringerOpen
2025-04-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-14141-w |
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| author | Qing-Hua Zhu |
| author_facet | Qing-Hua Zhu |
| author_sort | Qing-Hua Zhu |
| collection | DOAJ |
| description | Abstract Recent pulsar timing array collaborations have reported evidence of the stochastic gravitational wave background. The gravitational waves induced by primordial curvature perturbations, referred to as scalar-induced gravitational waves (SIGWs), could potentially be the physical origins of the gravitational wave background. Due to nonlinearity of Einstein’s gravity, there is non-Gaussianity of SIGWs even when the sourced primordial curvature perturbation is Gaussian. This paper investigates the intrinsic non-Gaussianity of SIGWs influenced by formation of primordial black holes. Specifically, we examine whether spectral width of Gaussian primordial curvature perturbations can affect non-Gaussianity of SIGWs. In order to ensure us to correctly quantify the degree of non-Gaussianity, we introduce an oscillation average scheme that can conserve the exact results of skewness of SIGWs. In this framework, the oscillation of SIGWs not only suppresses the bispectrum amplitude but also leads to a flattened-type bispectrum. Based on our results of skewness, it is found that the primordial curvature power spectrum with a narrower width can enhance the intrinsic non-Gaussianity. |
| format | Article |
| id | doaj-art-d2ac1015ccc4401ab6ddf03501ab41a7 |
| institution | OA Journals |
| issn | 1434-6052 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj-art-d2ac1015ccc4401ab6ddf03501ab41a72025-08-20T02:28:11ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-04-0185412010.1140/epjc/s10052-025-14141-wFlattened bispectrum of the scalar-induced gravitational wavesQing-Hua Zhu0School of Physics, Chongqing UniversityAbstract Recent pulsar timing array collaborations have reported evidence of the stochastic gravitational wave background. The gravitational waves induced by primordial curvature perturbations, referred to as scalar-induced gravitational waves (SIGWs), could potentially be the physical origins of the gravitational wave background. Due to nonlinearity of Einstein’s gravity, there is non-Gaussianity of SIGWs even when the sourced primordial curvature perturbation is Gaussian. This paper investigates the intrinsic non-Gaussianity of SIGWs influenced by formation of primordial black holes. Specifically, we examine whether spectral width of Gaussian primordial curvature perturbations can affect non-Gaussianity of SIGWs. In order to ensure us to correctly quantify the degree of non-Gaussianity, we introduce an oscillation average scheme that can conserve the exact results of skewness of SIGWs. In this framework, the oscillation of SIGWs not only suppresses the bispectrum amplitude but also leads to a flattened-type bispectrum. Based on our results of skewness, it is found that the primordial curvature power spectrum with a narrower width can enhance the intrinsic non-Gaussianity.https://doi.org/10.1140/epjc/s10052-025-14141-w |
| spellingShingle | Qing-Hua Zhu Flattened bispectrum of the scalar-induced gravitational waves European Physical Journal C: Particles and Fields |
| title | Flattened bispectrum of the scalar-induced gravitational waves |
| title_full | Flattened bispectrum of the scalar-induced gravitational waves |
| title_fullStr | Flattened bispectrum of the scalar-induced gravitational waves |
| title_full_unstemmed | Flattened bispectrum of the scalar-induced gravitational waves |
| title_short | Flattened bispectrum of the scalar-induced gravitational waves |
| title_sort | flattened bispectrum of the scalar induced gravitational waves |
| url | https://doi.org/10.1140/epjc/s10052-025-14141-w |
| work_keys_str_mv | AT qinghuazhu flattenedbispectrumofthescalarinducedgravitationalwaves |