Milagro Observations of Multi-TeV Emission from Galactic Sources in the Fermi Bright Source List

TL;DR

This study reports Milagro's detection of multi-TeV gamma-ray emission from several Galactic sources listed in the Fermi Bright Source List, extending observations into higher energy ranges with improved analysis techniques.

Contribution

It introduces a new optimized gamma-hadron separation analysis and utilizes 8 years of Milagro data to detect multi-TeV emissions from Fermi sources, including pulsars and nebulae.

Findings

Detection of multi-TeV emission from Fermi pulsar J2229.0+6114.

Extended multi-TeV emission associated with Geminga pulsar.

Milagro's sensitivity to gamma rays from 1 to 100 TeV.

Abstract

We present the result of a search of the Milagro sky map for spatial correlations with sources from a subset of the recent Fermi Bright Source List (BSL). The BSL consists of the 205 most significant sources detected above 100 MeV by the Fermi Large Area Telescope. We select sources based on their categorization in the BSL, taking all confirmed or possible Galactic sources in the field of view of Milagro. Of the 34 Fermi sources selected, 14 are observed by Milagro at a significance of 3 standard deviations or more. We conduct this search with a new analysis which employs newly-optimized gamma-hadron separation and utilizes the full 8-year Milagro dataset. Milagro is sensitive to gamma rays with energy from 1 to 100 TeV with a peak sensitivity from 10-50 TeV depending on the source spectrum and declination. These results extend the observation of these sources far above the Fermi energy band. With the new analysis and additional data, multi-TeV emission is definitively observed associated with the Fermi pulsar, J2229.0+6114, in the Boomerang Pulsar Wind Nebula (PWN). Furthermore, an extended region of multi-TeV emission is associated with the Fermi pulsar, J0634.0+1745, the Geminga pulsar.