Fengwu Sun, Steward Observatory
JWST/NIRCam Wide-Field Slitless Spectroscopy: In-flight Performance and First Sample of z>6 [OIII]+Halpha Line Emitters
In this talk, I will convince you that the Wide-Field Slitless Spectroscopic (WFSS) mode of JWST/NIRCam will become a game changer for the observation extragalactic astronomy. The in-flight spectral sensitivity of NIRCam WFSS is 20-40% higher than the pre-launch predictions, and it started to unveil the rest-frame optical emission lines (e.g., [OIII] 5007 and Halpha) of z>6 galaxies even with the shallow (10~20-min integration) commissioning data taken in April 2022. In two of our recent works, we discovered four z>6 [OIII]+Ha emitters using the flux-calibration data of NIRCam WFSS. I will show the first [OIII]/Hb-[NII]/Ha BPT diagram of galaxies in the Epoch of Reionization, and a nice mass-metallicity relation that suggests rapid metal enrichment with galaxies at z>6. We also obtain the first direct measurement of [OIII]5007 and Halpha luminosity functions at z>6, both are under-predicted by certain previous cosmological simulation by a factor of ~10. Our studies suggest an enhanced ionizing photon production rate in the early Universe, and the ubiquity of strong Hα and [O III] line emitters in the Epoch of Reionization, both will be further uncovered in the era of JWST.