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Las altas fracciones moleculares de gas en galaxias normales masivas de formación estelar en el Universo joven
L J Tacconi1, R Genzel, R Neri
1Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr. 1, 85748 Garching, Germany. linda@mpe.mpg.de
Nature
|February 12, 2010
Resumen
Las galaxias lejanas eran ricas en gas molecular, alimentando la rápida formación de estrellas. Este contenido de gas era significativamente mayor que en las galaxias actuales, lo que sugiere un mecanismo continuo de reposición de gas en el Universo temprano.
Área de la Ciencia:
- La astronomía es la astronomía.
- Cosmología Cosmología.
- La astrofísica es la astrofísica.
Sus antecedentes:
- Las estrellas se forman a partir de gas interestelar molecular frío, que es raro localmente, lo que limita la formación de estrellas en la Vía Láctea.
- Las galaxias masivas en el universo distante formaron estrellas mucho más rápido, lo que implica un mayor contenido de gas molecular.
- Las observaciones anteriores de gases moleculares se limitaban a objetos raros y luminosos como fusiones y cuásares.
Objetivo del estudio:
- Para investigar el contenido de gas molecular de galaxias típicas de formación estelar masiva en desplazamientos al rojo z ≈ 1.2 y z ≈ 2.3.
- Para entender la riqueza de gas y la eficiencia de la formación estelar en las primeras galaxias masivas.
- Para comparar las fracciones de gas en galaxias distantes con las del Universo local.
Principales métodos:
- Realizó una encuesta de gas molecular en muestras de galaxias típicas de formación de estrellas masivas.
- Las galaxias analizadas tienen desplazamientos al rojo medios
de aproximadamente 1.2 y 2.3.3. - Se midió la fracción de gas frío en relación con la masa bariónica total de la galaxia.
Principales resultados:
- Las galaxias distantes formadoras de estrellas eran significativamente ricas en gas, con fracciones de gas molecular 3-10 veces más altas que en las galaxias espirales masivas locales.
- En z = 2.3, la fracción media de gas frío fue de ~44%; en z = 1.2, fue de ~34%.
- La eficiencia de la formación estelar no dependía en gran medida de la época cósmica.
Conclusiones:
- Las galaxias jóvenes y masivas eran sustancialmente más ricas en gas molecular de lo que se suponía anteriormente.
- Las fracciones de gas observadas sugieren que las primeras galaxias requerían un mecanismo para la reposición semi-continua de gas fresco.
- Este hallazgo ayuda a explicar las rápidas tasas de formación estelar en el Universo temprano.
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