Detection prospects of the Telescope Array hotspot by space observatories

TL;DR

This paper evaluates the potential for space-based observatories to detect the Telescope Array's ultrahigh energy cosmic ray hotspot, estimating the required event counts for significant detection.

Contribution

It provides a quantitative analysis of detection prospects for the hotspot using KLYPVE and JEM-EUSO, considering different luminosity scenarios.

Findings

Approximately 300 events needed for 5σ detection at 68% probability.

Detection likelihood depends on the hotspot's luminosity.

Space observatories can potentially identify the hotspot if luminosity assumptions hold.

Abstract

In the present-day cosmic ray data, the strongest indication of anisotropy of the ultrahigh energy cosmic rays is the 20-degree hotspot observed by the Telescope Array with the statistical significance of 3.4\sigma. In this work, we study the possibility of detecting such a spot by space-based all-sky observatories. We show that if the detected luminosity of the hotspot is attributed to a physical effect and not a statistical fluctuation, the KLYPVE and JEM-EUSO experiments would need to collect ~300 events with E>57 EeV in order to detect the hotspot at the 5\sigma\ confidence level with the 68% probability. We also study the dependence of the detection prospects on the hotspot luminosity.