An international team of astronomers, utilizing the XMM-Newton, Chandra, and NuSTAR space telescopes, has investigated the characteristics of the recently identified very-high-energy source known as 2FHL J1745.1–3035. Detailed findings of the study, released on the pre-print server arXiv on Jan. 24, suggest the possibility that the source is a pulsar wind nebula. This exploration is part of the Second Fermi-LAT Catalog of High-Energy Sources (2FHL), which cataloged 360 sources in the 50 GeV–2 TeV energy range as part of NASA’s Fermi mission, including 12 very-high-energy (VHE) sources in the Galactic plane lacking current associations.
2FHL J1745.1–3035, positioned near the Galactic center, is among the unassociated VHE sources with a gamma-ray photon index lower than 1.8. Previous observations indicated its hard spectrum in gamma-rays above 50 GeV, classifying it as a TeV emitter. To provide more insights into this source, astronomers led by Stefano Marchesi from the University of Bologna conducted a comprehensive analysis using archival data from Chandra, NuSTAR, and XMM-Newton.
The researchers revealed that the X-ray source appears compact with no discernible extension, yet Chandra observations detected significantly extended emission up to around 5 arcseconds. Analyzing spectral properties, they found the source to be exceptionally hard at energies below 10 keV and notably softer in higher energy ranges. The study suggests a broken power law model with a break energy of about 7 keV best fits the broadband X-ray spectrum.
Based on their analysis, the astronomers propose that 2FHL J1745.1–3035 is likely a powerful pulsar wind nebula (PWN). Pulsar wind nebulae are formed by the pulsar’s wind colliding with its surroundings, creating charged particles and developing a nebula. If further studies confirm the PWN hypothesis, this would represent one of the most rigid PWNe ever detected in X-rays and the firmest in gamma-rays.”
