Revealing Double White Dwarf Mergers with Multi-messenger Signals

Abstract

Abstract A significant number of double white dwarfs (DWDs) are believed to merge within the Hubble time due to the gravitational wave (GW) emission during their inspiraling phase. The outcome of a DWD system is either a type Ia Supernova as the double-degenerate model, or a massive, long-lasting merger remnant. Expected multi-messenger signals of these events will help us to distinguish detailed merging physical processes. In this work, we aim to provide a generic scenario of DWD merging, investigate the emission of all major messengers, with a focus on GWs and neutrinos. Our goal is to provide some guidance for current and future (collaborative) efforts of multi-messenger observations. Throughout the merging evolution of a DWD system, different messengers (GW, neutrino and electromagnetic wave) will dominate at different times. In this work, we show that DWD merger events located at the distance of 1 kpc can indeed produce detectable signals of GWs and neutrinos. The GW frequency is in 0.3–0.6 Hz band around 10 days before tidal disruption begins. We estimate that in optimistic situations, the neutrino number detected by upcoming detectors such as JUNO and Hyper-Kamiokande can reach O(1) for a DWD merging event at ∼1 kpc.