# Gravitational Waves from Orphan Memory

## TL;DR

This paper introduces the concept of orphan gravitational-wave memory, which occurs without detectable parent signals, and discusses how LIGO can use this to detect or constrain high-frequency gravitational waves.

## Contribution

The paper proposes the novel concept of orphan memory and explores how LIGO can detect or limit high-frequency gravitational waves through this phenomenon.

## Key findings

- LIGO can place stringent limits on high-frequency gravitational waves.
- Orphan memory extends LIGO's effective bandwidth significantly.
- Future searches for orphan memory could reveal new astrophysical phenomena.

## Abstract

Gravitational-wave memory manifests as a permanent distortion of an idealized gravitational-wave detector and arises generically from energetic astrophysical events. For example, binary black hole mergers are expected to emit memory bursts a little more than an order of magnitude smaller in strain than the oscillatory parent waves. We introduce the concept of "orphan memory": gravitational-wave memory for which there is no detectable parent signal. In particular, high-frequency gravitational-wave bursts ($\gtrsim$ kHz) produce orphan memory in the LIGO/Virgo band. We show that Advanced LIGO measurements can place stringent limits on the existence of high-frequency gravitational waves, effectively increasing the LIGO bandwidth by orders of magnitude. We investigate the prospects for and implications of future searches for orphan memory.