Search for Spatially Extended Fermi-LAT Sources Using Two Years of Data

TL;DR

This paper introduces a new method to measure the spatial extension of gamma-ray sources detected by Fermi-LAT, validated through simulations, leading to the discovery of seven previously unrecognized extended sources.

Contribution

A novel technique for quantifying spatial extension in Fermi-LAT sources, validated by simulations and applied to identify new extended gamma-ray sources.

Findings

Validated the method with Monte Carlo simulations.

Calculated detection thresholds for spatial extension.

Discovered seven new spatially extended sources.

Abstract

Spatial extension is an important characteristic for correctly associating gamma-ray-emitting sources with their counterparts at other wavelengths and for obtaining an unbiased model of their spectra. We present a new method for quantifying the spatial extension of sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi). We perform a series of Monte Carlo simulations to validate this tool and calculate the LAT threshold for detecting the spatial extension of sources. We then test all sources in the second Fermi-LAT catalog (2FGL) for extension. We report the detection of seven new spatially extended sources.