Runaway stars as cosmic ray injectors inside molecular clouds

Author(s)

del Valle, M. V. ^{[1, 2]} ; Romero, G. E. ^{[1, 2]} ; Santos-Lima, R. ^[3]

Affiliation

^[1] Univ Nacl La Plata, Fac Ciencias Astron & Geofis, RA-1900 La Plata, Buenos Aires - Argentina

^[2] Inst Argentino Radioastron, RA-1894 Buenos Aires, DF - Argentina

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 448, n. 1, p. 207-220, MAR 21 2015.
• Web of Science Citations: 9

Abstract

Giant molecular clouds (GMCs) are a new population of gamma-ray sources, being the target of cosmic rays (CRs)-locally accelerated or not. These clouds host very young stellar clusters where massive star formation takes place. Eventually, some of the stars are ejected from the clusters, becoming runaway stars. These stars move supersonically through the cloud and develop bowshocks where particles can be accelerated up to relativistic energies. As a result, the bowshocks present non-thermal emission, and inject relativistic protons in the cloud. These protons diffuse in the GMC interacting with the matter. We present a model for the non-thermal radiation generated by protons and secondary pairs accelerated in the bowshocks of massive runaway stars within young GMCs. We solve the transport equation for primary protons and secondary pairs as the stars move through the cloud. We present non-thermal emissivity maps in radio and in gamma-rays as a function of time. We obtain X-ray luminosities of the order of similar to 1032 erg s(-1) and gamma-ray luminosities similar to 10(34) erg s(-1). We conclude that, under some assumptions, relativistic protons from massive runaway stars interacting with matter in GMCs give rise to extended non-thermal sources. (AU)

• FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support type: Multi-user Equipment Program
• FAPESP's process: 13/15115-8 - Study of collisionless plasma effects: application to the turbulent intracluster medium of galaxies
• Grantee: Reinaldo Santos de Lima
• Support type: Scholarships in Brazil - Post-Doctorate