Counterpart candidates to the unidentified Fermi source 0FGL J1848.6-0138

TL;DR

This study identifies potential counterparts to an unassociated Fermi gamma-ray source, highlighting a globular cluster and a possible pulsar wind nebula, and discusses their plausibility based on multi-wavelength data and theoretical models.

Contribution

It reports the first candidate counterparts for the gamma-ray source 0FGL J1848.6-0138, including a globular cluster and a pulsar wind nebula, advancing the identification of unassociated gamma-ray sources.

Findings

A globular cluster, GLIMPSE-C01, is a plausible gamma-ray counterpart.

A potential pulsar wind nebula inside the error box is identified.

Other interesting objects in the field are reported for future study.

Abstract

Aims. We aim here to contribute to the identification of unassociated bright sources of gamma-rays in the recently released catalogue obtained by the Fermi collaboration. Methods. Our work is based on a extensive cross-identification of sources from different wavelength catalogues and databases. Results. As a first result, we report the finding of a few counterpart candidates inside the 95% confidence error box of the Fermi LAT unidentified gamma-ray source 0FGL J1848.6$-$0138. The globular cluster GLIMPSE-C01 remarkably stands out among the most peculiar objects consistent with the position uncertainty of the gamma-ray source and with a conceivable physical scenario for gamma-ray production. The Fermi observed spectrum is compared against theoretical predictions in the literature making the association plausible but not yet certain due to its low X-ray to gamma-ray luminosity ratio. Other competing counterparts are also discussed. In particular, we pay a special attention to a possible Pulsar Wind Nebula inside the Fermi error box whose nature is yet to be confirmed. Conclusions.Both a globular cluster and an infrared source resembling a Pulsar Wind Nebula have been found in positional agreement with 0FGL J1848.6$-$0138. In addition, other interesting objects in the field are also reported. Future gamma-ray observations will narrow the position uncertainty and we hope to eventually confirm one of the counterpart candidates reported here. If GLIMPSE-C01 is confirmed, together with the Fermi possible detection of the well known globular cluster 47 Tuc, then it would provide strong support to theoretical predictions of globular clusters as gamma-ray sources.