Forecasts for detecting the gravitational-wave memory effect with Advanced LIGO and Virgo

Abstract

The detection of gravitational waves (GWs) from binary black holes (BBHs) has allowed the theory of general relativity to be tested in a previously unstudied regime: that of strong curvature and high GW luminosities. One distinctive and measurable effect associated with this aspect of the theory is the nonlinear GW memory effect. The GW memory effect is characterized by its effect on freely falling observers: the proper distance between their locations differs before and after a burst of GWs passes by their locations. Gravitational-wave interferometers, like the LIGO and Virgo detectors, can measure features of this effect from a single BBH merger, but previous work has shown that it will require an event that is significantly more massive and closer than any previously detected GW event. Finding evidence for the GW memory effect within the entire population of BBH mergers detected by LIGO and Virgo is more likely to occur sooner. A prior study has shown that the GW memory effect could be detected in a population of BBHs consisting of binaries like the first GW150914 event after roughly one-hundred events. In this paper, we compute forecasts of the time it will take the advanced LIGO and Virgo detectors (when the detectors are operating at their design sensitivities) to find evidence for the GW memory effect in a population of BBHs that is consistent with the measured population of events in the first two observing runs of the LIGO detectors. We find that after five years of data collected by the advanced LIGO and Virgo detectors the signal-to-noise ratio for the nonlinear GW memory effect in the population will be about three (near a previously used threshold for detection). We point out that the different approximation methods used to compute the GW memory effect can lead to notably different signal-to-noise ratios.

Computation of displacement and spin gravitational memory in numerical relativity

“…Over the past few years, there have been many studies of whether current or future GW detectors could measure the displacement and the spin memory effects [19][20][21][22][23][24]. These previous studies, however, used approximations of the memory since earlier calculations of the memory in a BBH merger have, until now, been incomplete.…”

Gravitational memory effects in Brans‐Dicke theory

“…As the displacement memories in the tensor and the scalar sectors cause the permanent changes in the configuration of the interferometer's arms, the basic ideas for detecting them should be similar to those used to detect GR's displacement memory effect (Boersma et al 2020; Hübner et al 2020; Johnson et al 2019; Lasky et al 2016; McNeill et al 2017). It is also possible to use pulsar timing arrays to detect them as in GR because the memory waveform generated by a supermassive binary black hole system can be modeled as a step function of time (Seto 2009; Wang et al 2015).…”

“…There are other memories, for example, velocity memory effect (Zhang et al 2017a, 2017b, 2018), none of which will be discussed in this work. Both displacement and spin memories might be detected by interferometers and pulsar timing arrays (Boersma et al 2020; Hübner et al 2020; Johnson et al 2019; Lasky et al 2016; Madison 2020; McNeill et al 2017; Seto 2009; Wang et al 2015), but it is difficult to observe the CM memory experimentally (Nichols 2018).…”

Gravitational memory effects and Bondi-Metzner-Sachs symmetries in scalar-tensor theories

“…It also stimulated the works on the asymptotic symmetry on the black hole horizon [25][26][27][28][29][30] and black hole information paradox [31]. The later opens up the possibility to examine the existence of this effect experimentally in the near future [32][33][34][35][36][37][38][39].…”