"A more probable explanation" is still impossible to explain GN-z11-flash: in response to Steinhardt et al. (arXiv:2101.12738)

TL;DR

This paper critiques a recent claim that a transient event near galaxy GN-z11 was caused by a Solar system object, defending the original interpretation and providing a new method to estimate the probability of such transients.

Contribution

It offers a critical analysis of Steinhardt et al.'s methodology, defends the original GN-z11-flash interpretation, and introduces a new approach to estimate the chance probability of similar transients.

Findings

Steinhardt et al.'s transients are mostly low-Earth orbit objects.

The original GN-z11-flash is unlikely from Solar system objects.

A new method estimates the probability of transient events in archival data.

Abstract

In Jiang et al. (2020), we reported a possible bright flash (hereafter GN-z11-flash) from a galaxy GN-z11 at z ~ 11. Recently, Steinhardt et al. (2021; arXiv:2101.12738) found 27 images with transient signals in Keck MOSFIRE archival data and claimed that GN-z11-flash was more likely from a moving object in our Solar system. We show that the Steinhardt et al.'s definition of the chance probability and their methodology of finding GN-z11-flash-like transients are problematic in several aspects. In particular, none of their transients is analogous to GN-z11-flash, and none of them is positionally coincident with a known object in their imaging data. In Jiang et al., we performed a comprehensive analysis of the origin of GN-z11-flash and ruled out, to the best of our knowledge, the possibility of known man-made objects or moving objects in the Solar system, based on all available information and our current understanding of these objects. Steinhardt et al. did not use such information and did not analyse the GN-z11-flash event itself. The majority of their transients are apparently low-Earth orbit satellites or aircrafts. Therefore, their analysis can neither prove nor disprove our results. Finally, we present a method to estimate the chance probability of finding GN-z11-flash-like transients in archival data. Based on this method and the archival data used by Steinhardt et al., we obtain a loose upper limit of the probability that actually support the original results of Jiang et al. (2020).