Yi-Fan Wang1, 2, Alexander H. Nitz1, 2
1. Albert-Einstein-Institut, Max-Planck-Institut for Gravitationsphysik, D-30167 Hannover, Germany
2. Leibniz Universitat Hannover, D-30167 Hannover, Germany
Sub-solar mass black hole binaries, due to their light mass, would have to be primordial in origin instead of the result of stellar evolution. Soon after formation in the early Universe, primordial black holes can form binaries after decoupling from the cosmic expansion. Alternatively, primordial black holes as dark matter could also form binaries in the late Universe due to dynamical encounters and gravitational-wave braking. A significant feature for this channel is the possibility that some sources retain non-zero eccentricity in the LIGO/Virgo band. Assuming all dark matter is primordial black holes with a delta function mass distribution, 1 Msun-1 Msun binaries formed in this late Universe channel can be detected by Advanced LIGO and Virgo with at their design sensitivities with a rate of O(1)/year, where 12%(3%) events have eccentricity at gravitational-wave frequency 10 Hz, e{10Hz}>=0.01(0.1), and non-detection can constrain the binary formation rate within this model. Third generation detectors would be expected to detect sub-solar mass eccentric binaries as light as 0.01 Msun within this channel, if they account for the majority of the dark matter. Furthermore, we use simulated gravitational-wave data to study the ability to search for eccentric gravitational-wave signals using quasi-circular waveform template bank with Advanced LIGO design sensitivity. Assuming binaries with a delta function mass of 0.1(1) Msun and the eccentricity distribution derived from this late Universe formation channel, for a match-filtering targeted search, 41%(6%) of the signals would be missed compared to ideal detection rate due to the mismatch in the gravitational-wave signal from eccentricity.
This is the associated code and data release for our paper, a preprint version is available on arxiv.
We acknowledge the Max Planck Gesellschaft and the Atlas cluster computing team at AEI Hannover for support.