Testing two-component jet models of GRBs with orphan afterglows

TL;DR

This paper proposes a method to test two-component jet models of gamma-ray bursts using orphan afterglows, predicting observable optical and X-ray peaks caused by different jet components, which can be detected through sky surveys.

Contribution

It introduces a novel observational test for two-component jet models of GRBs by identifying characteristic optical and X-ray peaks in orphan afterglows.

Findings

Two optical peaks are predicted at specific times due to jet components.

A bright X-ray peak is expected simultaneously with the first optical peak.

Monitoring the sky can validate the two-component jet model.

Abstract

In the \swift era, two-component jet models were introduced to explain the complex temporal profiles and the diversity of early afterglows. In this paper, we concentrate on the two-component jet model; first component is the conventional afterglow and second is the emission due to the late internal dissipation such as the late-prompt emission. We suggest herein that the two-component jet model can be probed by the existence of two optical peaks for orphan GRB afterglows. Each peak is caused by its respective jet as its relativistic beaming cone widens to encompass the off-axis line of sight. Typically, the first peak appears at $10^4-10^5$ s and the second at $10^5-10^6$ s. Furthermore, we expect to observe a single, bright X-ray peak at the same time as the first optical peak. Because orphan afterglows do not have prompt emission, it is necessary to monitor the entire sky every $10^4$ s in the X-ray regime. We can test the model with orphan afterglows through the X-ray all-sky survey collaboration and by using ground-based optical telescopes.