D. Milaković, J. K. Webb, P. Molaro, C.-C. Lee, P. Jethwa, G. Cupani, M. T. Murphy, L. Welsh, V. D'Odorico, S. Cristiani, R. Génova Santos, C. J. A. P. Martins, N. J. Nunes, T. M. Schmidt, F. A. Pepe, M. R. Zapatero Osorio, Y. Alibert, J. I. González Hernández, P. Di Marcantonio, E. Palle, R. Rebolo, N. C. Santos, S. G. Sousa, A. Suárez Mascareño

Abstract
Chemical evolution models predict a gradual build-up of ¹³C in the Universe, based on empirical nuclear reaction rates and assumptions on the properties of stellar populations. However, old metal-poor stars within the Galaxy contain more ¹³C than is predicted, suggesting that further refinements to the models are necessary. Gas at high-redshift provides important supplementary information at metallicities −2≲[Fe/H]≲−1 , for which there are only a few measurements in the Galaxy. We obtained new, high-quality, VLT/ESPRESSO observations of the QSO B1331 + 170 and used them to measure ¹²C/¹³C in the damped Lyman-α system (DLA) at z_abs=1.776 , with [Fe/H] = -1.27. AI-VPFIT, an artificial intelligence tool based on genetic algorithms and guided by a spectroscopic information criterion, was used to explore different possible kinematic structures of the carbon gas. Three hundred independent AI-VPFIT models of the absorption system were produced using pre-set ¹²C/¹³C values, ranging from 4 to 500. Our results show that ¹²C/¹³C=28.5^+51.5_−10.4 , suggesting a possibility of ¹³C production at low metallicity.

Keywords
galaxies: abundances, galaxies: ISM, quasars: absorption lines, quasars: individual: 1331+170

Monthly Notices of the Royal Astronomical Society
Volume 534, Issue 1, Page 12
2024 September

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