Detecting Lyman Alpha Emitters in the Sub-millimeter

TL;DR

This study predicts that a small but significant fraction of high-redshift Lyman Alpha Emitters can be detected in the sub-millimeter range using ALMA, providing insights into their dust content and physical conditions.

Contribution

It introduces a model linking Lyman Alpha emission to dust-reprocessed sub-millimeter radiation in LAEs, predicting their detectability with ALMA at high redshifts.

Findings

Approximately 1-3% of LAEs at z=5.7 and 6.6 detectable in submm with ALMA

LAEs are relatively dust-poor despite high metallicity

Detected fluxes exceed 0.12 mJy at 850 micrometers

Abstract

Using the results from a previously developed Lyman Alpha/continuum production/transmission and dust enrichment model for Lyman Alpha Emitters (LAEs), based on cosmological SPH simulations, we assess the detectability of their dust-reprocessed sub-millimeter (submm) radiation. As supernovae (rather than evolved stars) control dust formation and destruction processes, LAEs are relatively dust-poor with respect to local galaxies: they have low dust-to-gas ratios (0.05 times the dust-to-gas ratio of the Milky Way) in spite of their relatively high metallicity, which is approximately 10-50% of the solar value. Using the derived escape fraction of ultraviolet (UV) continuum photons we compute the UV luminosity absorbed by dust and re-emitted in the far infrared. The LAE submm fluxes correlate with their Lyman Alpha luminosity: about (3%, 1%) at z=(5.7, 6.6) of the LAEs in our simulated sample (those with with Log L_\alpha > 43.1) would have fluxes at 850 micrometer (the optimal band for detection) in excess of 0.12 mJy and will be therefore detectable at 5 sigma with ALMA with an integration time of only 1 hour. Such detections would open a new window on the physical conditions prevailing in these most distant galaxies.