Expanding Ejecta Method: II. Framework for Cosmological Distance Measurements via Intensity Interferometry

TL;DR

This paper proposes an expanded ejecta method using intensity interferometry to measure cosmic distances, offering a new, independent way to calibrate supernovae and determine the Hubble constant with high precision.

Contribution

It introduces three novel applications of the expanding ejecta method for cosmological distance measurements using intensity interferometry, including calibration of supernovae and constructing an independent Hubble diagram.

Findings

Forecasts Hubble constant precision of 1.6%, 1.1%, and 9.3% with next-generation interferometers.

Demonstrates potential for future improvements to 1.2%, 0.6%, and 1.5%.

Provides a geometric alternative for cosmic distance measurement.

Abstract

We explore the potential of the expanding ejecta method (EEM) as a cosmological probe, leveraging its ability to measure angular diameter distances to supernovae (SNe) with intensity interferometry. We propose three distinct applications of the EEM: (1) using Type IIP SNe as moderate-distance geometric anchors to calibrate Cepheids, replacing other local distance indicators; (2) directly calibrating Type Ia SNe, bypassing conventional calibration methods; (3) constructing a fully independent Hubble diagram with Type IIP (Type Ia) SNe, entirely decoupled from the traditional distance ladder. Incorporating realistic SN populations, we forecast a Hubble constant precision with next-generation intensity interferometers of $1.6\%$, $1.1\%$, and $9.3\% \,(3.6\%)$, respectively, for the three different proposed applications. Future intensity interferometry could yield improvements to $1.2\%$, $0.6\%$, and $1.5\%\,(0.4\%)$. The EEM thus offers a powerful geometric alternative for cosmic distance determination.