# Calibrating the cosmic distance ladder using gravitational-wave observations

## TL;DR

This paper explores how future third-generation gravitational-wave detectors can precisely calibrate the cosmic distance ladder by providing accurate distance measurements to supernova host galaxies, complementing traditional methods.

## Contribution

It demonstrates that advanced gravitational-wave detectors can significantly improve distance calibration for Type Ia supernovae, reducing uncertainties and aiding cosmological measurements.

## Key findings

- Third-generation detectors can measure distances within 0.1% to 3%.
- Current LIGO/Virgo measurements have ~50% errors.
- Gravitational waves can independently calibrate supernova distances.

## Abstract

Type Ia supernovae (SNe Ia) are among preeminent distance ladders for precision cosmology due to their intrinsic brightness, which allows them to be observable at high redshifts. Their usefulness as unbiased estimators of absolute cosmological distances however depends on accurate understanding of their intrinsic brightness, or anchoring their distance scale. This knowledge is based on calibrating their distances with Cepheids. Gravitational waves from compact binary coalescences, being standard sirens, can be used to validate distances to SNe Ia, when both occur in the same galaxy or galaxy cluster. The current measurement of distances by the advanced LIGO and Virgo detector network suffers from large statistical errors ($\sim 50\%$). However, we find that using a third generation gravitational-wave detector network, standard sirens will allow us to measure distances with an accuracy of $\sim 0.1\%$-$3\%$ for sources within $\le300$ Mpc. These are much smaller than the dominant systematic error of $\sim 5\%$ due to radial peculiar velocity of host galaxies. Therefore, gravitational-wave observations could soon add a new cosmic distance ladder for an independent calibration of distances to SNe Ia.