Spectroscopy with the JWST Advanced Deep Extragalactic Survey (JADES) --
  the NIRSpec/NIRCam GTO galaxy evolution project
  I present an overview of the JWST Advanced Deep Extragalactic Survey (JADES),
a joint program of the JWST/NIRCam and NIRSpec Guaranteed Time Observations
(GTO) teams involving 950 hours of observation. We will target two well-studied
fields with excellent supporting data (e.g., from HST-CANDELS): GOODS-North and
South, including the Ultra Deep Field. The science goal of JADES is to chart
galaxy evolution at z > 2, and potentially out to z > 10, using the rest-frame
optical and near-IR though observations from $\approx$ 1 - 5 $\mu$m.
Multi-colour NIRCam imaging with 9 filters will enable photometric redshifts
and the application of the Lyman break technique out to unprecedented
distances. NIRSpec spectroscopy (with spectral resolving powers of R = 100,
1000 & 2700) will measure secure spectroscopic redshifts of the
photometrically-selected population, as well as stellar continuum slopes in the
UV rest-frame, and hence study the role of dust, stellar population age, and
other effects. Measuring emission lines can constrain the dust extinction, star
formation rates, metallicity, chemical abundances, ionization and excitation
mechanism in high redshift galaxies. Coupling NIRCam and NIRSpec observations
will determine stellar populations (age, star formation histories, abundances)
of galaxies and provide the information to correct their broad-band spectral
energy distribution for likely line contamination. Potentially we can search
for signatures of Population III stars such as HeII. We can address the
contribution of star-forming galaxies at z > 7 to reionization by determining
the faint end slope of the luminosity function and investigating the escape
fraction of ionizing photons by comparing the UV stellar continuum with the
Balmer-line fluxes.
