C. G. Bernal*, W. H. Lee**, and Dany Page***
Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70–264, México D.F. 04510, México (* bernalcg@astroscu.unam.mx, ** wlee@astroscu.unam.mx, *** page@astroscu.unam.mx).
Received 2010 January 19
Accepted 2010 June 14
RESUMEN
]]> La acreción sobre una proto–estrella de neutrones en las horas que siguen al colapso del núcleo de la estrella masiva que le dio origen puede afectar sus propiedades observables. Este fenómeno se da en el régimen denominado hipercrítico (Chevalier 1989), donde el enfriamiento por neutrinos es crucial para la evolución termodinámica. En este trabajo presentamos un estudio en este contexto en una dimensión con simetría esférica y llevamos a cabo simulaciones numéricas en dos dimensiones dentro de una columna de acreción sobre una estrella de neutrones. Consideramos procesos microfísicos detallados, enfriamiento por neutrinos y la presencia de campos magnéticos en la aproximación de magnetohidrodinámica ideal. Comparamos nuestros resultados numéricos con las soluciones analíticas e investigamos cómo las soluciones, tanto hidrodinámicas como magnetohidrodinámicas, difieren de éstas. Iniciamos también una exploración de cómo este proceso puede afectar la aparición del remanente como un pulsar típico en radio.
ABSTRACT
The properties of a new–born neutron star, produced in a core–collapse supernova, can be strongly affected by the possible late fallback which occurs several hours after the explosion. This accretion occurs in the regime dominated by neutrino cooling, explored initially in this context by Chevalier (1989). Here we revisit this approach in a 1D spherically symmetric model and carry out numerical simulations in 2D in an accretion column onto a neutron star, considering detailed microphysics, neutrino cooling and the presence of magnetic fields in ideal MHD. We compare our numerical results with the analytic solutions and explore how the purely hydrodynamical as well as the MHD solutions differ from them, and begin to explore how this may affect the appearance of the remnant as a typical radio pulsar.
Key Words: accretion, accretion disks — hydrodynamics — magnetic fields — stars: neutron — supernovae: individual (SN1987A).
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ACKNOWLEDGMENTS
CGB acknowledges support from a DGEP– UNAM scholarship. Financial support for this work was provided in part by Conacyt (45845E) and DGAPA–Universidad Nacional Autónoma de México (IN 122609). The software used in this work was in part developed by the DOE–supported ASC/Alliance Center for Astrophysical Thermonuclear Flashes at the University of Chicago. The numerical calculations were carried out on the KanBalam Supercomputer at DGSCA, UNAM, whose support team is gratefully acknowledged. We thank the anonymous referee for comments and criticism which helped improve this final version.
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