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Galaxias en desplazamientos al rojo 5 a 6 con un contenido de polvo sistemáticamente bajo y una alta emisión [C II]
P L Capak1, C Carilli2, G Jones3
11] Infrared Processing and Analysis Center (IPAC), 1200 East California Boulevard, Pasadena, California 91125, USA [2] California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
Nature
|June 26, 2015
Resumen
Las primeras galaxias (des desplazamiento al rojo z > 4) tienen significativamente menos polvo y mayor emisión de carbono II en comparación con épocas cósmicas posteriores. Esto sugiere un medio interestelar en rápida evolución en el Universo joven.
Área de la Ciencia:
- La evolución cósmica es la evolución cósmica.
- Formación y evolución de las galaxias.
- Propiedades del medio interestelar.
Sus antecedentes:
- Las propiedades galácticas ultravioletas con desplazamiento al rojo z > 4 sugieren una rápida evolución de oscurecimiento del polvo.
- Las mediciones anteriores del medio interestelar en las primeras galaxias estaban limitadas por suposiciones y capacidades de detección.
Objetivo del estudio:
- Para medir directamente las propiedades del medio interestelar en las primeras galaxias de formación estelar.
- Para investigar el contenido de polvo y gas de las galaxias aproximadamente mil millones de años después del Big Bang (z ≈ 5-6).
Principales métodos:
- Se midió la emisión prohibida de carbono II ([C II]) del gas.
- Se midió la emisión de infrarrojo lejano del polvo en nueve galaxias típicas de formación estelar en z ≈ 5-6.
Principales resultados:
- Estas galaxias tempranas exhiben una emisión térmica inferior a 1/12 de la de galaxias similares en épocas posteriores (z < 3).
- La emisión mejorada [C II] en relación con el continuo del infrarrojo lejano indica una relación gas-polvo diferente.
- El gas se distribuye en 1-8 kiloparsecs con diversas dinámicas.
Conclusiones:
- El medio interestelar en las primeras galaxias evolucionó significativamente, con sustancialmente menos polvo que las galaxias a z < 3.
- El contenido de polvo en estas galaxias tempranas es comparable a los sistemas locales de baja metalicidad.
- Estos hallazgos desafían las suposiciones anteriores sobre la composición y evolución de las primeras galaxias.
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