Resolving the Formation of Protogalaxies. III. Feedback from the First Stars
John H. Wise – NASA / GSFC; Stanford University / KIPAC
Tom Abel – Stanford University / KIPAC
Abstract
The first stars form in dark matter halos of masses ~106 Msun as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding dark matter halos. We use cosmological adaptive mesh refinement simulations that include self-consistent Population III star formation and feedback to examine the properties of assembling early dwarf galaxies. Accurate radiative transport is modeled with adaptive ray tracing. We include supernova explosions and follow the metal enrichment of the intergalactic medium. The calculations focus on the formation of several dwarf galaxies and their progenitors. In these halos, baryon fractions in 108 solar mass halos decrease by a factor of 2 with stellar feedback and by a factor of 3 with supernova explosions. We find that radiation feedback and supernova explosions increase gaseous spin parameters up to a factor of 4 and vary with time. Stellar feedback, supernova explosions, and H2 cooling create a complex, multi-phase interstellar medium whose densities and temperatures can span up to 6 orders of magnitude at a given radius. The pair-instability supernovae of Population III stars alone enrich the halos with virial temperatures of 104 K to approximately 10-3 of solar metallicity. We find that 40% of the heavy elements resides in the intergalactic medium (IGM) at the end of our calculations. The highest metallicity gas exists in supernova remnants and very dilute regions of the IGM.
Movies
High Resolution Images
Projections:
These movies follow the evolution of the most massive progenitor from the first star to when it reaches a virial temperature of 104 K.
Density:
Star Formation Only (SimA, SimB)
+Supernova Feedback (SimB)
Temperature:
Star Formation Only (SimA, SimB)
+Supernova Feedback (SimB)
Metallicity:
+Supernova Feedback (SimB)
Figure 6: Density-Temperature phase diagram 45,000 years after a supernova, colored by metallicity. There is a clear trend toward lower metallicity in dense gas. The supernova remnant is seen in the hot adiabat, reaching up to 107 K.
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Figure 5: Density-Temperature phase diagrams of the gas within a virial radius of the dwarf galaxy. Pop III stellar feedback and H2 cooling create a multi-phase ISM in these complex objects.
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Figure 4: Radial profile of the same dwarf galaxy (M ~ 3 x 107 Msun) that shows the wide spread in densities and temperatures at any given radius.
(view)
Figures 1 and 2: Density-squared gas density and temperature projections, comparing the cases without star formation, with star formation, and with supernova feedback.
Higher resolution image (1546x1280) for Simulation A:
Contact: John Wise (john {dot} h {dot} wise {at} nasa {dot} gov
Figures 7 and 8: Metallicity projections of the volume surrounding the most massive halo. The metal filling fraction is only 3.5% at z = 17. In the figure that focuses on the dwarf galaxy, it is clear that the IGM is preferentially enriched.
(dwarf galaxy – 1.2 kpc; IGM – 8.6 kpc field of view)
