|
The First Stars and Galaxies: Challenges for the Next Decade Participants
Contact: |
Poster
Title: Ultraviolet and Infrared Radiation from Protogalaxies Author(s): Hidenobu Yajima Abstract: The UV sources responsible for cosmic reionization are still an unsolved issue. The likeliest candidates are high redshift protoglaxies. At present, estimates of reionization by protoglaxies suffer from uncertainties in ionizing UV escape fractions. To derive escape fractions for primordial galaxies, we perform three-dimensional radiative transfer in high-resolution hydrodynamical simulations that include supernovae feedback. We find that protogalaxies can be highly ionized by intense UV radiation from young stars, with escape fractions in excess of 15%. Escape fractions from protogalaxies decrease with chemical evolution because of dust extinction. Using our results and observational data, we show that high-z LAEs and LBGs can be ionizing sources of the IGM at z = 3-6 but not at z > 7. We also examine the infrared properties of protogalaxies, in which UV from stars is absorbed by dust and reradiated in the infrared. Infrared from high-z galaxies is shifted to submillimeter wavelengths by cosmological redshift and is hence a promising target for ALMA. We model the surface brightness distributions of protogalaxies at submillimeter wavelengths and discuss the likelihood of their detection.
|