# Systematic Bias Due to Nonspinning Template Waveforms in the Gravitational Wave Parameter Estimation for Aligned-Spin Binary Black Holes

## TL;DR

This paper investigates how using nonspinning waveform templates in gravitational wave data analysis can lead to significant biases in estimating parameters of aligned-spin binary black hole mergers, highlighting the importance of including spin effects.

## Contribution

It demonstrates the extent of bias introduced by nonspinning templates in parameter estimation for aligned-spin BBHs and compares it to statistical uncertainties.

## Key findings

- Nonspinning templates can cause significant bias in mass parameter estimation.
- Bias can exceed statistical uncertainties, affecting the validity of nonspinning templates.
- Systematic bias depends on the true spin and mass parameters.

## Abstract

We study the parameter estimation of gravitational waves for aligned-spin binary black hole (BBH) signals and assess the impact of bias that can be produced by using nonspinning template waveforms. We employ simple methods to calculate the statistical uncertainty from an overlap distribution. For the fiducial waveform model, we use a phenomenological model, which is designed to generate the gravitational waveforms emitted from merging BBH systems. We show that the mass parameters recovered by nonspinning waveform templates can be significantly biased from the true values of aligned-spin signals. By comparing the systematic bias with the statistical uncertainty, we examine the validity of nonspinning templates for the parameter estimation of aligned-spin BBHs.