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Galaxias de disco fuertemente dominadas por bariones en el pico de la formación de galaxias hace diez mil millones de
R Genzel1,2, N M Förster Schreiber1, H Übler1
1Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching, Germany.
Nature
|March 17, 2017
Resumen
Las primeras galaxias masivas eran dominadas por bariones, con menos materia oscura que las galaxias locales. Este estudio revela velocidades de rotación decrecientes en sus discos externos, desafiando los modelos estándar de materia oscura.
Área de la Ciencia:
- Cosmología
- Formación y evolución de las galaxias
- La astrofísica
Sus antecedentes:
- La cosmología de la materia oscura fría (CDM) postula que las galaxias están incrustadas en halos de materia oscura.
- Las curvas de rotación de la galaxia local muestran velocidades constantes o crecientes con el radio, apoyando el CDM.
- Estudios anteriores sugirieron altas fracciones bariónicas en las primeras galaxias, pero no fueron concluyentes con respecto a la masa de la materia oscura.
Objetivo del estudio:
- Para investigar las curvas de rotación de los discos externos en galaxias masivas de formación estelar a alto desplazamiento al rojo.
- Para probar las predicciones del modelo estándar de materia oscura fría en el Universo temprano.
- Para entender el papel de los bariones y la materia oscura en la formación temprana de galaxias.
Principales métodos:
- Observación de las curvas de rotación (velocidad de rotación frente al radio del disco) para seis galaxias masivas formadoras de estrellas.
- Análisis de la masa dinámica inferida de las velocidades de rotación.
- Comparación de la masa dinámica inferida con las estimaciones de masa estelar y de gas.
Principales resultados:
- Se encontró que las velocidades de rotación en los discos externos de las galaxias de alto desplazamiento al rojo disminuían con el aumento del radio.
- Esta tendencia sugiere un dominio bariónico significativo en las primeras galaxias masivas.
- La disminución observada indica que la materia oscura estaba menos concentrada en el Universo temprano en comparación con el Universo local.
Conclusiones:
- Las galaxias masivas en el Universo temprano eran más dominadas por bariones de lo que se suponía anteriormente.
- Los discos de galaxias de alto desplazamiento al rojo experimentaron un término de presión sustancial debido a la gran dispersión de velocidad.
- Los bariones se condensaron eficientemente en los centros de los halos de materia oscura durante el Universo temprano.
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