GrismZ
Where emission lines land in JWST slitless spectroscopy at a given redshift, and which redshifts a single detected line allows.
Lines at z = 5.2
Redshift windows
Redshift range over which each line falls inside each selected filter (between the filter's half-power wavelengths).
What could a line at 4.12 µm be?
"Expected in coverage" lists lines that should appear in the same filter if the identification is right, so the absence of the strong ones argues against it. Relative strengths are typical of star-forming galaxies and AGN at high redshift; dust, metallicity and excitation change them.
Notes
- Filter curves: , normalised to peak = 1. A line is "in" a filter when the filter transmits at least half its peak there.
- Line-spread FWHM used for blending: NIRCam grism ≈ 25 Å (R ≈ 1600 at 4 µm), NIRISS GR150 ≈ 95 Å (R ≈ 150 at 1.4 µm). Real NIRCam spectra can also lose the blue or red end depending on where the source sits in the field.
- Rest wavelengths are in vacuum. Blended doublets ([O II] 3726,3729, Mg II, C IV, C III]) use their mean wavelength.