2024ApJ...976..122N -
Astrophys. J., 976, 122 (2024/November-3)
Low [O/Fe] Ratio in a Luminous Galaxy at the Early Cosmic Epoch (z > 10): Signature of Short Delay Time or Bright Hypernovae/Pair-instability Supernovae?
NAKANE M., OUCHI M., NAKAJIMA K., HARIKANE Y., TOMINAGA N., TAKAHASHI K., KASHINO D., YANAGISAWA H., WATANABE K., NOMOTO K., ISOBE Y., NISHIGAKI M., ISHIGAKI M.N., ONO Y. and TAKEDA Y.
Abstract (from CDS):
We present an [O/Fe] ratio of a luminous galaxy GN-z11 at z = 10.60 derived with the deep public JWST/NIRSpec data. We fit the medium-resolution grating (G140M, G235M, and G395M) data with the model spectra consisting of BPASS-stellar and CLOUDY-nebular spectra in the rest-frame UV wavelength ranges with Fe absorption lines, carefully masking the other emission and absorption lines in the same manner as previous studies conducted for lower-redshift (z ∼ 2-6) galaxies with oxygen abundance measurements. We obtain an Fe-rich abundance ratio $[{\rm{O}}/\mathrm{Fe}]=-{0.37}_{-0.22}^{+0.43}$, which is confirmed with the independent deep prism data as well as by the classic 1978 index method. This [O/Fe] measurement is lower than that measured for star-forming galaxies at z ∼ 2-3. Because z = 10.60 is an early epoch after the Big Bang (∼430 Myr) and the first star formation (likely ∼200 Myr), it is difficult to produce Fe by Type Ia supernovae (SNe Ia), which requires sufficient delay time for white-dwarf formation and gas accretion. The Fe-rich abundance ratio in GN-z11 suggests that the delay time is short or that the major Fe enrichment is not accomplished by SNe Ia but by bright hypernovae (BrHNe) and/or pair-instability supernovae (PISNe), where the yield models of BrHNe and PISNe explain Fe, Ne, and O abundance ratios of GN-z11. The [O/Fe] measurement is not too low to rule out the connection between GN-z11 and globular clusters (GCs) previously suggested by the nitrogen abundance but rather supports the connection with a GC population at high [N/O] if a metal dilution process exists.
Abstract Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Galaxy chemical evolution - Galaxy evolution - Galaxy formation - High-redshift galaxies - Star formation
Simbad objects:
3
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