Spectral Analysis of the 13 keV Feature in XTE J1810-197: Implications for AXP Models

TL;DR

This study analyzes a 13 keV emission feature in XTE J1810-197, finding atomic emission from Rubidium in a Keplerian ring best explains the observations, supporting the Quark nova model over other AXP models.

Contribution

It provides a detailed spectral analysis of the 13 keV feature, comparing multiple models and identifying atomic Rubidium emission as the most consistent explanation.

Findings

Atomic Rubidium emission fits the data best.

Cyclotron emission is less likely due to positional coincidence.

Supports the Quark nova model for AXP environment.

Abstract

During 2003 and 2004 the Anomalous X-Ray Pulsar XTE J1810-197 went through a series of four bursts. The spectrum in the tail of one of these bursts shows a strong, significant emission feature ~13 keV, thereby encoding a wealth of information about the environment surrounding this object. In this paper we analyse this emission feature considering both cyclotron and atomic emission processes and weigh our findings against three leading AXP models: the Magnetar model, Fall-back disk model and the Quark nova model. We find that atomic emission from Rubidium within a Keplerian ring ($\sim$15 km from a compact object of $\sim 2M_\odot$) is the most consistent scenario with the observations, supporting the Quark nova model. Cyclotron emission from an atmosphere a few hundred meters thick also fits the feature well, but is ruled out on account of its positional coincidence in three separate AXP sources.