Preparing for JWST with HST/COS spectroscopy of Pox 186: a local analogue of z > 6 galaxies

ALMA and JWST has revolutionized the study of reionization-era galaxies. It is crucial to establish a local reference sample of high-redshift “analog” galaxies covering essential UV, optical and FIR emission lines that have become available in the upcoming JWST+ALMA era. A local, metal-poor blue compact dwarf galaxy, Pox 186, exhibits the brightest CIII] 1908 emission (equivalent width ~36 A) observed at any redshifts as revealed by the HST/COS observations, along with an extreme [OIII] 88/[CII] 158 (~ 10). This extreme CIII] is comparable to those observed in galaxies at redshifts of z ~ 6-7, when the reionization process is thought to be completed. In this contribution, we present the analysis of UV nebular and stellar lines as revealed in this galaxy by the HST/COS observations. The work is very timely as JWST is now routinely observing the reionization era galaxies.