Lyα profile shape as an escape-fraction diagnostic at high redshift
arxiv(2024)
摘要
While the shape of the Lyα profile is viewed as one of the best
tracers of ionizing-photon escape fraction (f_esc) within low redshift
(z 0.3) surveys of the Lyman continuum, this connection remains untested at
high redshift. Here, we combine deep, rest-UV Keck/LRIS spectra of 80 objects
from the Keck Lyman Continuum Spectroscopic Survey with rest-optical
Keck/MOSFIRE spectroscopy in order to examine potential correlations between
Lyα profile shape and the escape of ionizing radiation within z 3
star-forming galaxies. We measure the velocity separation between double-peaked
Lyα emission structure (v_ sep), between red-side Lyα
emission peaks and systemic (v_ Lyα,red), and between red-side
emission peaks and low-ionization interstellar absorption lines (v_
Lyα-LIS). We find that the IGM-corrected ratio of ionizing to
non-ionizing flux density is significantly higher in KLCS objects with lower
v_ Lyα,red. We find no significant trend between measures of
ionizing-photon escape and v_ Lyα-LIS. We compare our results to
measurements of z 0.3 "Green Peas" from the literature and find that KLCS
objects have larger v_ sep at fixed v_ Lyα,red, larger
f_esc at fixed v_ Lyα,red, and higher v_ Lyα,red
overall than z 0.3 analogs. We conclude that the Lyα profile shapes of
our high-redshift sources are fundamentally different, and that measurements of
profile shape such as v_ Lyα,red map on to f_esc in different
ways. We caution against building reionization-era f_esc diagnostics based
purely on Lyα profiles of low-redshift dwarf galaxies. Tracing v_
sep, v_ Lyα,red, and f_esc in a larger sample of z 3 galaxies
will reveal how these variables may be connected for galaxies at the epoch of
reionization.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要