1810.08185
The physics of Lyman-alpha escape from high-redshift galaxies
Smith, et al
Lyman-alpha (Lya) photons from ionizing sources and cooling radiation undergo a complex resonant scattering process that generates unique spectral signatures in high-z galaxies. Present a detailed Lya radiative transfer study of a cosmological zoom-in simulation from the Feedback in Realistic Environments (FIRE) project. Focus on the time, spatial, and angular properties of the Lya emission over a redshift range of z=5-7, after escaping the galaxy and being transmitted through the intergalactic medium (IGM). Over this epoch, the target galaxy has an average stellar mass of M_star ~ 5e8 Msun. Find that many of the interesting features of the Lya one can be understood in terms of the galaxy's SFH. The time variability, spatial morphology, and anisotropy of Lya properties are consistent with current observations. For example, the rest frame equivalent width has a EW_Lya,0>20A duty cycle of 62% with a non-negligible number of sightlines with >100A, associated with outflowing regions of a starburst with greater coincident UV continuum absorption, as these conditions generate the redder, narrower (or single peaked) line profiles. The lowest equivalent widths correspond to cosmo filaments, which have little impact on UV continuum photons but efficiently trap Lya and produce bluer, broader lines with less transmission through the IGM. Also show that in dense self-shielding low-metallicity filaments and satellites Lya radiation pressure can be dynamically important. Finally, despite a significant reduction in surface brightness with increasing redshift, Lya detection and spectroscopy of high-z galaxies with the upcoming JWST is feasible.
No comments:
Post a Comment