Accurate Standard Siren Cosmology with Joint Gravitational-Wave and γ-Ray Burst Observations

Area of Science:

• Cosmology
• Astrophysics
• Gravitational-wave astronomy

Background:

• Joint gravitational-wave and gamma-ray burst (GRB) observations are key for standard siren cosmology.
• A significant selection effect arises from the requirement of coincident GRB detection, limiting observations to sources with small inclination angles.

Purpose of the Study:

• To address the systematic uncertainty caused by selection effects in joint gravitational-wave and GRB observations.
• To enable unbiased measurements of the Hubble constant and constrain GRB emission properties.

Main Methods:

• Inferring the a priori unknown electromagnetic detection probability directly from multimessenger data.
• Developing a novel likelihood approximant for gravitational-wave events that exactly treats distance and inclination dependence.

Main Results:

• Successfully removed the severe source of bias induced by selection effects.
• Enabled an unbiased measurement of the Hubble constant.
• Provided constraints on GRB emission properties and accurate measurement of source viewing angles.

Conclusions:

• The proposed inference scheme is applicable to real data, even in a small-statistics regime.
• This method enhances the precision of cosmological measurements using standard sirens.
• The approach paves the way for future advancements in multimessenger astronomy and cosmology.