S18B0014abst
S18B0014
This is a resubmission of our approved proposal S18A-053, which was lost due to bad weather. We propose FOCAS spectroscopy for a newly discovered sample of 11 intensely Lyα-emitting galaxies (Lyα EW0 = 240−600Å) at z=3−5. These large Lyα EW galaxies (LLEGs) are good candidates of high-redshift metal-poor, extremely young galaxies such as a few Myr stellar population with metallicity of only Z ∼ 0.001 that is as low as those of the most metal-poor local galaxies including I Zw 18 (Z ∼ 0.0006) or possibly even lower. These LLEGs are identified in the latest HSC survey data, whose effective volume is >10 times larger than previous narrowband searches. We carefully remove transients from our sample by checking multi-epoch observation images. However, without spectroscopy, we cannot rule out the possibilities of low-z line emitters and AGNs. With the FOCAS spectra, we will spectroscopically confirm our LLEGs at high redshifts and examine the presence of AGN signatures. We will derive the number densities of this very rare population, which will be useful to constrain the duty cycle of intermittent star formation activities. Our spectroscopy program will yield a unique sample of high-z galaxies in an early phase of galaxy formation that have been poorly explored so far.
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