A supernova distance to the anchor galaxy NGC 4258

TL;DR

This paper uses a supernova in galaxy NGC 4258 to calibrate the standard candle method for type IIP supernovae, providing a distance estimate consistent with maser measurements and exploring calibration improvements.

Contribution

It introduces an alternative local calibration for the standard candle method using galaxies with Cepheid distances, reducing scatter in supernova distance estimates.

Findings

Distance estimate to NGC 4258 is 7.08±0.86 Mpc.

Calibration based on Cepheid-hosting galaxies reduces scatter to 0.16 mag.

Results are consistent with maser-based distance measurements.

Abstract

The fortuitous occurrence of a type II-Plateau (IIP) supernova, SN 2014bc, in a galaxy for which distance estimates from a number of primary distance indicators are available provides a means with which to cross-calibrate the standardised candle method (SCM) for type IIP SNe. By applying calibrations from the literature we find distance estimates in line with the most precise measurement to NGC 4258 based on the Keplerian motion of masers (7.6$\pm$0.23\,Mpc), albeit with significant scatter. We provide an alternative local SCM calibration by only considering type IIP SNe that have occurred in galaxies for which a Cepheid distance estimate is available. We find a considerable reduction in scatter ($\sigma_I = 0.16$\, mag.), but note that the current sample size is limited. Applying this calibration, we estimate a distance to NGC 4258 of $7.08\pm0.86$ Mpc.