Probing strange quark matter objects with future space-based gravitational wave detectors DECIGO and BBO

The Strange Quark Matter (SQM) hypothesis posits that objects composed of SQM could exist across a wide mass range, from strange planets (SPs) to strange stars (SSs). It has been proposed that gravitational waves (GWs) emitted by inspiraling SS-SP systems may be detectable by ground-based GW observatories such as advanced LIGO and the Einstein Telescope. Nevertheless, such a system may undergo an extended period of orbital evolution in a close configuration before entering the inspiraling phase. During this time, it can generate continuous GW signals at frequencies ranging from milli-hertz (mHz) to deci-hertz (dHz). The detailed characteristics of these GWs have not yet been thoroughly explored. In this study, we delve into the continuous GW features of SS-SP systems, with a focus on exploring the physically viable parameter space. We compared the GW signals emitted by these systems to the sensitivity curves of next-generation space-based GW detectors like the Deci-hertz Interferometer Gravitational wave Observatory (DECIGO) and the Big Bang Observer (BBO). Our analyses demonstrate that both the DECIGO and BBO detectors are capable of detecting continuous GWs from SS-SP systems across a broad parameter space. These GWs carry important information for testing the SQM hypothesis, as well as for advancing our understanding of supernovae and compact star merger processes.