Science with the space-based interferometer eLISA. I: Supermassive black hole binaries

TL;DR

This study evaluates various eLISA mission designs for detecting and characterizing supermassive black hole binaries, highlighting how configuration differences impact scientific capabilities and potential astrophysical insights.

Contribution

It compares multiple eLISA configurations and assesses their ability to detect and analyze supermassive black hole mergers across different formation scenarios.

Findings

All configurations can detect some black hole binaries.

Six-link configurations with lower noise provide richer data.

Enhanced configurations may identify electromagnetic counterparts.

Abstract

We compare the science capabilities of different eLISA mission designs, including four-link (two-arm) and six-link (three-arm) configurations with different arm lengths, low-frequency noise sensitivities and mission durations. For each of these configurations we consider a few representative massive black hole formation scenarios. These scenarios are chosen to explore two physical mechanisms that greatly affect eLISA rates, namely (i) black hole seeding, and (ii) the delays between the merger of two galaxies and the merger of the black holes hosted by those galaxies. We assess the eLISA parameter estimation accuracy using a Fisher matrix analysis with spin-precessing, inspiral-only waveforms. We quantify the information present in the merger and ringdown by rescaling the inspiral-only Fisher matrix estimates using the signal-to-noise ratio from non-precessing inspiral-merger-ringdown phenomenological waveforms, and from a reduced set of precessing numerical relativity/post-Newtonian hybrid waveforms. We find that all of the eLISA configurations considered in our study should detect some massive black hole binaries. However, configurations with six links and better low-frequency noise will provide much more information on the origin of black holes at high redshifts and on their accretion history, and they may allow the identification of electromagnetic counterparts to massive black hole mergers.