Near-infrared/optical identification of five low-luminosity X-ray pulsators

TL;DR

This study identifies likely near-infrared and optical counterparts of five low-luminosity X-ray pulsators, using multiwavelength observations to determine their nature as either neutron star systems or intermediate polars.

Contribution

The paper provides the first multiwavelength identification and classification of five low-luminosity X-ray pulsators, clarifying their nature using combined X-ray, near-infrared, and optical data.

Findings

Three sources have confirmed near-infrared counterparts.

Two sources are likely intermediate polars.

Two sources most likely harbor accreting neutron stars.

Abstract

We present the identification of the most likely near-infrared/optical counterparts of five low-luminosity X-ray pulsators (AX J1700.1-4157, AX 1740.1-2847, AX J1749.2-2725, AX J1820.5-1434 and AX J1832.3-0840) which have long pulse periods (> 150 s). The X-ray properties of these systems suggest that they are likely members of persistent high mass X-ray binaries or intermediate polars. Using our Chandra observations, we detected the most likely counterparts of three sources (excluding AX J1820.5-1434 and AX J1832.3-0840) in their ESO - NTT near-infrared observations, and a possible counterpart for AX J1820.5-1434 and AX J1832.3-0840 in the 2MASS and DSS observations respectively. We also performed the X-ray timing and spectral analysis for all the sources using our XMM-Newton observations, which further helped us to constrain the nature of these systems. Our multiwavelength observations suggest that AX J1749.2-2725 and AX J1820.5-1434 most likely harbor accreting neutron stars while AX J1700.1-4157, AX J1740.1-2847 and AX J1832.3-0840 could be intermediate polars.