Kavli Affiliate: Roberto Maiolino
| First 5 Authors: Roberta Tripodi, Francesco D’Eugenio, Roberto Maiolino, Mirko Curti, Jan Scholtz
| Summary:
We present the first statistical investigation of spatially resolved
emission-line properties in a sample of 63 low-mass galaxies at $4leq z<10$,
using JWST/NIRSpec MSA data from the JWST Advanced Deep Extragalactic (JADES)
survey focusing on deep, spatially resolved spectroscopy in the GOODS-S
extragalactic field. By performing a stacking of the 2D spectra of the galaxies
in our sample, we find an increasing or flat radial trend with increasing
radius for [OIII]$lambda5007$/H$beta$ and a decreasing one for
[NeIII]$lambda3869$/[OII]$lambda3727$ (3–4 $sigma$ significance). These
results are still valid when stacking the sample in two redshift bins (i.e.,
$4leq z<5.5$ and $5.5leq z<10$). The comparison with star-formation
photoionization models suggests that the ionization parameter increases by
$sim 0.5$ dex with redshift. We find a tentative metallicity gradient that
increases with radius (i.e., ‘inverted’) in both redshift bins. Moreover, our
analysis reveals strong negative gradients for the equivalent width of Hbeta
(7$sigma$ significance). This trend persists even after removing known AGN
candidates, therefore, it is consistent with a radial gradient primarily in
stellar age and secondarily in metallicity. Taken all together, our results
suggest that the sample is dominated by active central star formation, with
possibly inverted metallicity gradients sustained by recent episodes of
accretion of pristine gas or strong radial flows. Deeper observations and
larger samples are needed to confirm these preliminary results and to validate
our interpretation.
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