Nature and Nurture? Comparing Ly$\alpha$ Detections in UV-Bright and Fainter [O III]+H$\beta$ Emitters at $z\sim8$ With Keck/MOSFIRE

Understand

The 100% detection rate of Ly$\alpha$ emission in a sample of four luminous $z\sim8$ galaxies with red Spitzer/IRAC colors suggests objects with unusual ionizing capabilities that created early ionized bubbles in a neutral era.

• Whether such bubbles reflect enhanced ionizing properties (nature) or an overdense environment (nurture), however, remains unclear.
• Here we aim to distinguish between these hypotheses via a search for Ly$\alpha$ emission in five fainter galaxies drawn from the CANDELS-GOODS fields using a similar IRAC excess and UV magnitudes that should reflect reduced clustering effects.
• Using Keck/MOSFIRE we tentatively detect $>4\sigma$ line emission in only two targets at redshifts $z_{\rm Ly\alpha}$=7.1081 and $z_{\rm Ly\alpha}$=7.9622 with rest-frame EWs of 16-17 A, $\sim$1.5$\times$ weaker compared to their brighter counterparts.