Properties of Near-Infrared Selected AGN Candidates with 2MASS/ROSAT Catalogues

TL;DR

This study identifies and analyzes near-infrared selected AGN candidates from 2MASS/ROSAT catalogues, confirming their properties and potential as reliable AGN indicators through multiwavelength analysis.

Contribution

It introduces a method combining positional and color criteria to extract reliable AGN candidates from X-ray and near-infrared data, expanding AGN identification techniques.

Findings

Many candidates are confirmed as known AGNs.

Properties of candidates align with those of established AGNs.

Some unclassified sources show different multiwavelength properties.

Abstract

We report on the near-infrared selected AGN candidates extracted from 2MASS/ROSAT catalogues and discuss their properties. First, near-infrared counterparts of a X-ray source in ROSAT catalogues (namely, Bright Source Catalogue (BSC) and Faint Source Catalogue (FSC)) were extracted by positional cross-identification of <=30''. Because these counterparts would contain many mis-identifications, we further imposed near-infrared colour selection criteria and extracted reliable AGN candidates (BSC: 5,273, FSC: 10,071). Of 5,273 (10,071) candidates in the BSC (FSC), 2,053 (1,008) are known AGNs. Near-infrared and X-ray properties of candidates show similar properties with known AGNs and are consistent with previous studies. We also searched for counterparts in other wavelengths (that is, optical, near-infrared, and radio), and investigated properties in multiwavelength. No significant difference between known AGNs and unclassified sources could be seen. However, some unclassified sources in the FSC showed slightly different properties compared with known AGNs. Consequently, it is highly probable that we could extract reliable AGN candidates though candidates in the FSC might be spurious.