TeV Gamma-Ray Sources from a Survey of the Galactic Plane with Milagro

TL;DR

This paper reports a survey of the Galactic plane using Milagro, detecting multiple TeV gamma-ray sources, some spatially extended, with fluxes comparable to the Crab nebula, and associating them with known sources like EGRET objects.

Contribution

First comprehensive survey of Galactic TeV gamma-ray sources at ~20 TeV using Milagro, identifying new sources and confirming associations with known objects.

Findings

Detected 8 candidate sources with >4.5σ significance.

Four sources, including Crab nebula, are confirmed with >4σ significance.

Sources have fluxes ranging from 25% to nearly equal to Crab flux.

Abstract

A survey of Galactic gamma-ray sources at a median energy of ~20 TeV has been performed using the Milagro Gamma Ray Observatory. Eight candidate sources of TeV emission are detected with pre-trials significance $>4.5\sigma$ in the region of Galactic longitude $l\in[30^\circ,220^\circ]$ and latitude $b\in[-10^\circ,10^\circ]$. Four of these sources, including the Crab nebula and the recently published MGRO J2019+37, are observed with significances $>4\sigma$ after accounting for the trials involved in searching the 3800 square degree region. All four of these sources are also coincident with EGRET sources. Two of the lower significance sources are coincident with EGRET sources and one of these sources is Geminga. The other two candidates are in the Cygnus region of the Galaxy. Several of the sources appear to be spatially extended. The fluxes of the sources at 20 TeV range from ~25% of the Crab flux to nearly as bright as the Crab.