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La supresión de la formación de galaxias enanas por la reionización cósmica
J Stuart B Wyithe1, Abraham Loeb
1University of Melbourne, Parkville, Victoria 3010, Australia. swyithe@physics.unimelb.edu.au
Nature
|May 20, 2006
Resumen
Las galaxias del universo temprano muestran la formación de galaxias enanas suprimidas después de la reionización. Las galaxias post-reionización requerían una masa mínima de 10^10.9 masas solares, lo que impactó en las tasas de formación estelar cósmica.
Área de la Ciencia:
- Cosmología Cosmología.
- Formación y evolución de las galaxias.
- El Universo Temprano Astrofísica Astrofísica
Sus antecedentes:
- Descubrimientos recientes revelan numerosas galaxias débiles formadas en los primeros mil millones de años después del Big Bang.
- Las fluctuaciones en estas distribuciones de galaxias tempranas influyeron en la fracción de ionización del hidrógeno cósmico.
- Los modelos teóricos predicen la supresión de la formación de galaxias enanas después de la reionización cósmica, causando una disminución en la formación estelar.
Objetivo del estudio:
- Proporcionar evidencia observacional para la supresión predicha de la formación de galaxias enanas después de la reionización cósmica.
- Para determinar la masa mínima de las galaxias responsables de la radiación ionizante en el corrimiento al rojo z ≈ 5.5.5.
Principales métodos:
- Análisis de la dispersión observada en la fracción de ionización del hidrógeno cósmico a lo largo de las líneas de visión de los primeros cuásares.
- Comparación de la dispersión observada con predicciones teóricas basadas en distribuciones de masas de galaxias.
- Utilizando datos de recientes descubrimientos de galaxias tempranas y débiles.
Principales resultados:
- Se informa de la evidencia de la supresión de la formación de galaxias enanas después de la reionización cósmica.
- Las galaxias que aportan la mayor parte de la radiación ionizante con desplazamiento al rojo z ≈ 5,5 deben haber tenido masas que exceden aproximadamente 10 ^ 10.9 ± 0.5 masas solares.
- Esta masa mínima es significativamente mayor (dos órdenes de magnitud) que la masa de las galaxias que se cree que han dominado la reionización.
Conclusiones:
- Los hallazgos apoyan las predicciones teóricas de la formación de galaxias enanas suprimidas después de la reionización.
- Una población distinta de galaxias más masivas dominó la radiación ionizante después de la reionización.
- Se espera que las futuras encuestas de telescopios infrarrojos identifiquen galaxias más tempranas y más pequeñas responsables de la reionización inicial antes de la supresión de galaxias enanas.
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