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Imágenes de rayos X de alta resolución de un núcleo de un cúmulo globular: binarios compactos en 47Tuc
J E Grindlay1, C Heinke, P D Edmonds
1Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. josh@cfa.harvard.edu
Science (New York, N.Y.)
|May 19, 2001
Resumen
El Observatorio de rayos X Chandra tomó imágenes del cúmulo globular 47 Tucanae, revelando una densa población de binarios compactos. La mayoría de las fuentes son púlsares de milisegundos (MSP) y enanas blancas en acrecentamiento, no estrellas de neutrones.
Área de la Ciencia:
- La astronomía y la astrofísica.
- Astronomía de rayos X La astronomía de rayos X es una ciencia.
- Las poblaciones estelares.
Sus antecedentes:
- Los cúmulos globulares son sistemas estelares densos que ofrecen entornos únicos para estudiar poblaciones de objetos compactos.
- Comprender la población binaria en los cúmulos globulares es crucial para la evolución y dinámica estelar.
Objetivo del estudio:
- Para investigar la población de binarios compactos en el núcleo de alta densidad estelar del cúmulo globular 47 Tucanae (NGC 104).
- Para caracterizar la naturaleza de las fuentes de rayos X dentro del cúmulo utilizando imágenes de rayos X de alta resolución.
Principales métodos:
- Imágenes de rayos X profundas de 47 Tucanae utilizando el Observatorio de rayos X Chandra (exposición de 70 kilosegundos).
- Análisis de las características espectrales y temporales de los rayos X.
- Correlación cruzada con las observaciones de radio de los púlsares de milisegundos (MSP) y las identificaciones ópticas del Telescopio Espacial Hubble.
Principales resultados:
- Se detectó una población centralmente concentrada de al menos 108 fuentes débiles de rayos X dentro de la zona central de 2' x 2.5'.
- Se identificaron todos los 15 púlsares de milisegundos (MSP) conocidos, con 13 resueltos por Chandra.
- Las poblaciones de origen se estiman en >50% de MSP, ~30% de enanas blancas en acreción, ~15% de binarios de secuencia principal en llamas y 2-3 binarios de rayos X de baja masa en reposo.
- Se colocó un límite superior de ~470 masas solares en un agujero negro central en acreción.
Conclusiones:
- El estudio proporciona el primer diagrama de rayos X de "color-magnitud" para un cúmulo globular.
- Se estableció un censo exhaustivo del objeto compacto y la población binaria en 47 Tucanae.
- Los resultados desafían los modelos convencionales de formación de MSP, sugiriendo vías alternativas dentro de densos entornos estelares.
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