Speaker
Description
Extreme emission line galaxies (EELGs) are typically characterized by high equivalent widths (EWs) which are driven by elevated specific star formation rates (sSFR) in low-mass galaxies with subsolar metallicities and little dust. Such extreme systems are exceedingly rare in the local universe, but the number density of EELGs increases with redshift. Such starburst galaxies are currently presumed to be the main drivers of hydrogen reionization over 5.5<z<15, which motivates the searches for high-z EELGs. In this talk, I will present the study of the physical properties of a sample of ~1000 EELGs at 4<z<9 photometrically selected from the CEERS survey using JWST/NIRCam. We create synthetic NIRCam observations of EELGs using empirical templates based on ~2000 local metal-poor starbursts (MPS) to select EELGs based on color-color criteria. We study their properties based on SED fitting and flux excess in the photometric filters. We consider a delayed-tau model for the star formation history and find EELGs are young with a mean value of the time after the onset of star formation of 93Myr. We find that they have similar line ratios to local MPS with high log([OIII]/Hbeta)>0.4 which indicates that star formation may be the dominant source of ionization. We find an increase of EW([OIII]+Hbeta) with sSFR and SFR surface density, and a decrease with age and stellar mass. The sample of EELGs can reach high SFR surface density and high O32>5 which indicates they may have the conditions to facilitate the escape of ionizing photons.
