Numerical simulations show the formation of self-gravitating primordial disks during the assembly of the first structures in the Universe, in particular, during the formation of Population III and supermassive stars. Their subsequent evolution is expected to be crucial in determining the mass scale of the first cosmological objects, which depends on the temperature of the gas and dominant cooling mechanism. Here, we derive a one-zone framework to explore the chemical evolution of these disks and show that viscous heating leads to the collisional dissociation of an initially molecular gas. The effect is relevant on scales of 10 AU (1000 AU) for a central mass of 10 M⊙ (104 M⊙) at an accretion rate of 10-1 M⊙ yr-1, and provides a substantial heat input to stabilize the disk. If the gas is initially atomic, it remains atomic during the further evolution and the effect of viscous heating is less significant. The additional thermal support is particularly relevant for the formation of very massive objects, such as the progenitors of the first supermassive black holes. The stabilizing impact of viscous heating thus alleviates the need for strong radiation background as a means of keeping the gas atomic.

The chemical evolution of self-gravitating primordial disks

FERRARA, ANDREA;
2015

Abstract

Numerical simulations show the formation of self-gravitating primordial disks during the assembly of the first structures in the Universe, in particular, during the formation of Population III and supermassive stars. Their subsequent evolution is expected to be crucial in determining the mass scale of the first cosmological objects, which depends on the temperature of the gas and dominant cooling mechanism. Here, we derive a one-zone framework to explore the chemical evolution of these disks and show that viscous heating leads to the collisional dissociation of an initially molecular gas. The effect is relevant on scales of 10 AU (1000 AU) for a central mass of 10 M⊙ (104 M⊙) at an accretion rate of 10-1 M⊙ yr-1, and provides a substantial heat input to stabilize the disk. If the gas is initially atomic, it remains atomic during the further evolution and the effect of viscous heating is less significant. The additional thermal support is particularly relevant for the formation of very massive objects, such as the progenitors of the first supermassive black holes. The stabilizing impact of viscous heating thus alleviates the need for strong radiation background as a means of keeping the gas atomic.
File in questo prodotto:
File Dimensione Formato  
aa26356-15.pdf

accesso aperto

Descrizione: journal article full text
Tipologia: Altro materiale allegato
Licenza: Accesso gratuito (sola lettura)
Dimensione 681.02 kB
Formato Adobe PDF
681.02 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11384/64707
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 6
  • ???jsp.display-item.citation.isi??? 5
social impact