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We present an online, open, and comprehensive template library of gravitational waveforms produced during the tidal disruptions of stars by massive black holes, spanning a broad space of parameters. We build this library thanks to a new feature that we implement in the general relativistic version of phantom , a smoothed particle hydrodynamics code for three dimensional simulations in general relativity. We first perform a series of numerical tests to show that the gravitational wave (GW) signal obtained is in excellent agreement with the one expected from theory. This benchmark is done for well studied scenarios (such as binary stellar systems). We then apply our code to calculate the GW signals from tidal disruption events, finding that our results are consistent with the theoretical estimates obtained in previous studies for selected parameters. We illustrate interesting results from the catalog, where we stress how the gravitational signal is affected by variations of some parameters (like black hole spin, stellar orbital eccentricity, and inclination). The full catalog is available online. It is intended to be a living catalog. [ABSTRACT FROM AUTHOR]

In this paper, we derive the gravitational wave stochastic background from tidal disruption events (TDEs). We focus on both the signal emitted by main-sequence stars disrupted by supermassive black holes (SMBHs) in galaxy nuclei and on that from disruptions of white dwarfs by intermediate-mass black holes (IMBHs) located in globular clusters. We show that the characteristic strain h c's dependence on frequency is shaped by the pericenter distribution of events within the tidal radius and under standard assumptions h c∝ f −1/2. This is because, the TDE signal is a burst of gravitational waves at the orbital frequency of the closest approach. In addition, we compare the background characteristic strains with the sensitivity curves of the upcoming generation of space-based gravitational wave interferometers: the Laser Interferometer Space Antenna (LISA), TianQin, ALIA , the DECI-hertz inteferometer Gravitational wave Observatory (DECIGO), and the Big Bang Observer (BBO). We find that the background produced by main-sequence stars might be just detected by BBO in its lowest frequency coverage, but it is too weak for all the other instruments. On the other hand, the background signal from TDEs with white dwarfs will be within reach of ALIA , and especially of DECIGO and BBO , while it is below the LISA and TianQin sensitive curves. This background signal detection will not only provide evidence for the existence of IMBHs up to redshift z ∼ 3, but it will also inform us on the number of globular clusters per galaxy and on the occupation fraction of IMBHs in these environments. [ABSTRACT FROM AUTHOR]

Stars are spheres of gas held together by self-gravity. When flying by a black hole, however, the star self-binding force can be overwhelmed by the black hole tides and the star can be torn apart. This is a physically rich and fascinating event which will be described by first introducing the concept of black hole from a mathematical point of view. We will then dive into the physics of the tidal disruption and proceed describing the accompanying electromagnetic flare and gravitational wave burst in the frequency range of the Laser Interferometer Space Antenna. This empowers such events to discover the elusive black holes with mass intermediate between the solar and the million/billion solar masses. [ABSTRACT FROM AUTHOR]

Gravitational waves can be emitted by accretion discs if they undergo instabilities that generate a time varying mass quadrupole. In this work we investigate the gravitational signal generated by a thick accretion disc of 1 M⊙ around a static supermassive black hole of 106 M⊙, assumed to be formed after the tidal disruption of a solar type star. This torus has been shown to be unstable to a global non-axisymmetric hydrodynamic instability, the Papaloizou–Pringle instability, in the case where it is not already accreting and has a weak magnetic field. We start by deriving analytical estimates of the maximum amplitude of the gravitational wave signal, with the aim to establish its detectability by the Laser Interferometer Space Antenna (LISA). Then, we compare these estimates with those obtained through a numerical simulation of the torus, made with a 3D smoothed particle hydrodynamics code. Our numerical analysis shows that the measured strain is two orders of magnitude lower than the maximum value obtained analytically. However, accretion discs affected by the Papaloizou–Pringle instability may still be interesting sources for LISA, if we consider discs generated after deeply penetrating tidal disruptions of main-sequence stars of higher mass. [ABSTRACT FROM AUTHOR]