Getting ready for JWST with new-generation spectral models and interpretation tools
Intervenant : Jacopo Chevallard
The James Webb Space Telescope (JWST), scheduled for launch in October 2018, will open a largely unexplored observational window at near- to mid-infrared wavelengths (0.6-28 micron). In particular, the Near-InfraRed Spectrograph (NIRSpec) on board JWST will allow the detection of standard UV and optical emission lines out to redshift ~ 10 and beyond for large samples of galaxies. This will provide unique insight into, for example, the star formation activity and early chemical enrichment of galaxies, the co-evolution of galaxies and AGNs, the impact of stellar and AGN feedback, and the main drivers of cosmic reionization. One of the first large programs to exploit the new observational capabilities of JWST will be the NIRSpec Guaranteed-Time-Observations (GTO) program, which includes a multi-layered survey in Multi-Object-Spectroscopy (MOS) mode targeting ~104 galaxies at 1.5 < z < 10, as well as an Integral-Field-Unit (IFU) survey targeting ~60 galaxies and AGNs out to z~9.
In this talk, after a short review of JWST and the NIRSpec GTO program, I will present a set of physically-motivated simulations of NIRSpec and NIRCam (the Near-Infrared Camera on board JWST) observations, which we have used to optimise the survey design, and which will be made available to the community on time for the preparation of Cycle-1 General-Observer (GO) observations (call for proposals on 30/11/2017). I will also discuss a new set of state-of-the-art population synthesis+photoionization models, developed in collaboration with the NEOGAL team at the IAP, tailored to the interpretation of high-redshift galaxy observations. I will show how these models, incorporated into our new-generation analysis tool "Beagle", successfully reproduce a broad range of UV and optical features from high-quality spectra of nearby galaxies, as well as the high-ionization UV lines observed in galaxies at z > 6. The ability to self-consistently measure the physical properties of gas and stellar populations across a broad range of redshifts and stellar masses will be crucial to maximise the scientific return of JWST and gain unique insight into the evolution of galaxies across cosmic times.