# Fast Extragalactic X-ray Transients From Gamma Ray Bursts Viewed Far Off Axis

## TL;DR

This paper classifies fast extragalactic X-ray transients into two populations: short-duration XRF pulses from off-axis long GRBs and longer-duration afterglows from off-axis short GRBs, based on archival Chandra data.

## Contribution

It identifies and characterizes two distinct populations of X-ray transients, providing insights into their origins and relation to gamma ray bursts viewed off-axis.

## Key findings

- Two populations of XRTs with distinct durations identified
- Short XRTs linked to off-axis long GRBs (XRFs)
- Long XRTs associated with off-axis short GRB afterglows

## Abstract

The observed lightcurves and estimated sky rate of fast extragalactic x-ray transients (XRTs) discovered in archival Chandra data indicate that they belong to two distinct XRT populations. The first population of relatively short duration pulses, which typically last less than few minutes seems to be pulses of x-ray flashes (XRFs), which are nearby long duration gamma ray bursts viewed from far off axis. The second population of much longer pulses, which typically last hours, seems to be the early time afterglows of short gamma ray bursts (SGRBs) which are beamed away from Earth, as was shown in a previous paper.