A study of the association of Fermi sources with massive young galactic objects^⋆

¹ Departament d’Astronomia i MeteorologiaInstitut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, 08028 Barcelona, Spain
e-mail: pmunar@am.ub.es
² Instituto Argentino de Radioastronomía, CONICET, C.C.5, Villa Elisa, 1894, Argentina
e-mail: romero@iar.unlp.edu.ar
³ Facultat de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque, La Plata 1900, Argentina

Received: 25 January 2011
Accepted: 21 March 2011

Abstract

Massive protostars have associated bipolar outflows that can produce strong shocks when they interact with the surrounding medium. At these shocks, particles can be accelerated up to relativistic energies. Relativistic electrons and protons can then produce gamma-ray emission, as some theoretical models predict. To identify young galactic objects that may emit gamma rays, we crossed the Fermi First Year Catalog with some catalogs of known massive young stellar objects (MYSOs), early type stars, and OB associations, and we implemented Monte Carlo simulations to find the probability of chance coincidences. We obtained a list of massive MYSOs that are spatially coincident with Fermi sources. Our results indicate that  ~70% of these candidates should be gamma-ray sources with a confidence of  ~5σ. We studied the coincidences one by one to check the viability of these young sources as potential counterparts to Fermi sources and made a short list of best targets for new detailed multifrequency observations. The results for other type of young galactic objects are not conclusive.