The high-energy emission from HD 93129A near periastron

DEL PALACIO, S; GARCÍA, F; ALTAMIRANO, D; BARBÁ, R H; BOSCH-RAMON, V; CORCORAN, M; DE BECKER, M; HAMAGUCHI, K; MAÍZ APELLÁNIZ, J; MUNAR ADROVER, P; PAREDES, J M; ROMERO, G E; SANA, H; TAVANI, M; UD-DOULA, A

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 494 p. 6043 - 6052

0035-8711

We conducted an observational campaign towards one of the most massive and luminous colliding wind binaries in the Galaxy, HD~93129A, close to its periastron passage in 2018. During this time the source was predicted to be in its maximum of high-energy emission. Here we present our data analysis from the X-ray satellites extit{Chandra} and extit{NuSTAR} and the γ-ray satellite extit{AGILE}. High-energy emission coincident with HD~93129A was detected in the X-ray band up to ∼18~keV, whereas in the γ-ray band only upper limits were obtained. We interpret the derived fluxes using a non-thermal radiative model for the wind-collision region. We establish a conservative upper limit for the fraction of the wind kinetic power that is converted into relativistic electron acceleration, fNT,e0.3~G. We also argue a putative interpretation of the emission from which we estimate fNT,e≈0.006 and BWCR≈0.5~G. We conclude that multi-wavelength, dedicated observing campaigns during carefully selected epochs are a powerful tool for characterising the relativistic particle content and magnetic field intensity in colliding wind binaries.