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Formación estelar primordial significativa en desplazamientos al rojo z aproximadamente 3-4
1Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, USA. raulj@physics.upenn.edu
Nature
|March 24, 2006
Resumen
Las estrellas primordiales, no enriquecidas con elementos pesados, explican los datos intrigantes de las líneas ultravioletas y de emisión de las primeras galaxias. Este hallazgo sugiere una mezcla ineficiente de metales en galaxias con altos desplazamientos al rojo.
Área de la Ciencia:
- La astronomía y la astrofísica.
- Evolución cósmica de la evolución cósmica.
- Formación de galaxias Formación de galaxias
Sus antecedentes:
- Observaciones recientes de galaxias con alto desplazamiento al rojo presentan anomalías en la emisión de fotones ultravioleta (UV) y en las líneas espectrales.
- Específicamente, las galaxias de ruptura de Lyman (LBGs) muestran emisiones UV y Lyman alfa inesperadas, y una fuerte línea de emisión de He II, desafiando los modelos existentes.
Objetivo del estudio:
- Para resolver inconsistencias en las explicaciones actuales de múltiples rompecabezas observacionales relativas a las galaxias de alto desplazamiento al rojo.
- Proponer un modelo unificado que tenga en cuenta las características anómalas de los rayos UV y las líneas de emisión en las primeras galaxias.
Principales métodos:
- Análisis de los datos de observación de las galaxias de alto desplazamiento al rojo, centrándose en los espectros UV y de las líneas de emisión.
- Modelado de escenarios de formación de galaxias que incorporan diversos grados de poblaciones de estrellas primordiales y mezcla de metales.
Principales resultados:
- Un modelo que incorpora 10-30% de estrellas primordiales (libres de metales) en galaxias con desplazamiento al rojo z ≈ 3-4 resuelve simultáneamente cuatro desafíos observacionales clave.
- Estos desafíos incluyen el exceso de emisión de rayos UV, la emisión de Lyman alfa de regiones extendidas, fuertes líneas Lyman alfa y la presencia de una línea de emisión de He II.
Conclusiones:
- La presencia de una fracción significativa de estrellas primordiales en las primeras galaxias es una explicación viable para los fenómenos observados.
- Esto implica una ineficiente micro mezcla de metales dentro de las galaxias en escalas de tiempo gigáreas, en contra de muchos modelos jerárquicos de formación de galaxias.
- Simulaciones futuras de alta resolución y observaciones de líneas de emisión He II pueden verificar esta conclusión.
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