Inspiraling double compact object detection and lensing rate -- forecast for DECIGO and B-DECIGO

TL;DR

This paper forecasts the detection and lensing rates of inspiraling double compact objects by DECIGO and B-DECIGO, highlighting their potential to explore low-frequency gravitational waves and contribute to multi-messenger astronomy.

Contribution

It introduces the first population synthesis-based estimates of DCO inspiral rates for DECIGO and assesses gravitational lensing prospects for these detectors.

Findings

DECIGO could detect 10^4 - 10^5 DCO inspirals annually.

B-DECIGO could detect 10^2 - 10^4 DCO inspirals annually.

DECIGO may observe 5-50 lensed NS-NS inspirals and up to 100 lensed BH-BH inspirals.

Abstract

Emergence of gravitational wave (GW) astronomy revived the interest in exploring the low frequency GW spectrum inaccessible from the ground. Satellite GW observatory DECIGO in its original configuration and the currently proposed smaller scale B-DECIGO are aimed to cover deci-Hertz part of the GW spectrum, which fills the gap between LISA mili-Hertz and deca- to kilo-Hertz range probed by ground-based detectors. In this paper we forecast the detection rates of inspiraling double compact objects (DCOs) and the unresolved confusion noise from these sources in DECIGO and B-DECIGO. In the context of DECIGO we use, for the first time, the population synthesis intrinsic inspiral rates of NS-NS, BH-NS and BH-BH systems. We also estimate the expected gravitational lensing rates of such sources for DECIGO and B-DECIGO. The result is that yearly detection of DCOs inspirals for the DECIGO is of order of $10^4 - 10^5$, while for a much smaller scale B-DECIGO they are about $10^2 - 10^4$ depending on the DCO population considered. Taking into account that considerable part of these events would be detectable by ground-based GW observatories the added value of DECIGO/B-DECIGO could be substantial. DECIGO will also be able to register $5-50$ lensed NS-NS inspirals and up to O(100) BH-BH inspirals. On the contrary, predictions for the B-DECIGO are pessimistic: only the optimistic common envelope scenario of DCO formation could yield a few lensed BH-BH inspirals per year. We also address the question of the magnification bias in the GW event catalogs of DECIGO and B-DECIGO.