Gravitational waves induced by the local-type non-Gaussian curvature perturbations. (arXiv:2007.10686v2 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_C/0/1/0/all/0/1">Chen Yuan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_Q/0/1/0/all/0/1">Qing-Guo Huang</a>

The current observational constraints still leave a substantial mass window
$sim [10^{-16},10^{-14}] cup [10^{-13},10^{-12}] M_odot$ for primordial
black holes (PBHs) representing all of dark matter (DM) in our Universe. The
gravitational waves (GWs) induced by the curvature perturbations are inevitably
generated during the formation of these PBHs, and fall in the frequency band of
LISA. Such scalar induced gravitational waves (SIGWs) are supposed to be
definitely detected by LISA even when the second-order local-type
non-Gaussianity characterized by the parameter $F_{rm NL}$ is taken into
account. In this letter, we give a comprehensive analysis of the GWs induced by
the local-type non-Gaussian curvature perturbations up to the third-order
denoted by the non-linear parameter $G_{rm NL}$, and find that a log-dependent
slope of SIGWs in the infrared region is generically predicted and the
amplitude of SIGWs can be further suppressed by several orders of magnitude.
Therefore, the null-detection of SIGWs by LISA cannot rule out the possibility
of PBHs making up all of DM.

The current observational constraints still leave a substantial mass window
$sim [10^{-16},10^{-14}] cup [10^{-13},10^{-12}] M_odot$ for primordial
black holes (PBHs) representing all of dark matter (DM) in our Universe. The
gravitational waves (GWs) induced by the curvature perturbations are inevitably
generated during the formation of these PBHs, and fall in the frequency band of
LISA. Such scalar induced gravitational waves (SIGWs) are supposed to be
definitely detected by LISA even when the second-order local-type
non-Gaussianity characterized by the parameter $F_{rm NL}$ is taken into
account. In this letter, we give a comprehensive analysis of the GWs induced by
the local-type non-Gaussian curvature perturbations up to the third-order
denoted by the non-linear parameter $G_{rm NL}$, and find that a log-dependent
slope of SIGWs in the infrared region is generically predicted and the
amplitude of SIGWs can be further suppressed by several orders of magnitude.
Therefore, the null-detection of SIGWs by LISA cannot rule out the possibility
of PBHs making up all of DM.

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