Molecular isotopologue measurements toward super star clusters and the relation to their ages in NGC 253 with ALCHEMI
Artikel i vetenskaplig tidskrift, 2024
Context. Determining the evolution of the CNO isotopes in the interstellar medium (ISM) of starburst galaxies can yield important constraints on the ages of super star clusters (SSCs), or on other aspects and factors contributing to their evolution, such as the initial mass function (IMF). Due to the time-dependent nature of the abundances of isotopes within the ISM -as they are supplied from processes such as nucleosynthesis or chemical fractionation -, this provides the opportunity to test whether or not isotope ratios trace the ages of highly star-forming regions, such as SSCs.
Aims. The goal of this study is to investigate whether the isotopic variations in SSC regions within NGC 253 are correlated with their different ages as derived from stellar population modelling.
Methods. We measured abundance ratios of CO, HCN, and HCO+ isotopologues in six regions containing SSCs within NGC 253 using high-spatial-resolution (1.6″, ~28 pc) data from the ALCHEMI (ALma Comprehensive High-resolution Extragalactic Molecular Inventory) ALMA Large program. We then analysed these ratios using RADEX radiative transfer modelling, with the parameter space sampled using the nested sampling Monte Carlo algorithm MLFriends. These abundance ratios were then compared to ages predicted in each region via the fitting of observed star-formation tracers (such as Brγ) to Starburst99 starburst stellar population evolution models.
Results. We determined the isotopic column density ratios across multiple regions of SSC activity in NGC 253 using non-LTE radiative transfer modelling. We do not find any significant trend with age for the CO and HCN isotopologue ratios on timescales of the ages of the SSC∗ regions observed. However, HCO+ may show a correlation with age over these timescales in 12C/13C.
Conclusions. The driving factors of these ratios within SSCs could be the IMF or fractionation effects. To further probe these effects in SSCs over time, a larger sample of SSCs must be observed spanning a larger age range.
Aims. The goal of this study is to investigate whether the isotopic variations in SSC regions within NGC 253 are correlated with their different ages as derived from stellar population modelling.
Methods. We measured abundance ratios of CO, HCN, and HCO+ isotopologues in six regions containing SSCs within NGC 253 using high-spatial-resolution (1.6″, ~28 pc) data from the ALCHEMI (ALma Comprehensive High-resolution Extragalactic Molecular Inventory) ALMA Large program. We then analysed these ratios using RADEX radiative transfer modelling, with the parameter space sampled using the nested sampling Monte Carlo algorithm MLFriends. These abundance ratios were then compared to ages predicted in each region via the fitting of observed star-formation tracers (such as Brγ) to Starburst99 starburst stellar population evolution models.
Results. We determined the isotopic column density ratios across multiple regions of SSC activity in NGC 253 using non-LTE radiative transfer modelling. We do not find any significant trend with age for the CO and HCN isotopologue ratios on timescales of the ages of the SSC∗ regions observed. However, HCO+ may show a correlation with age over these timescales in 12C/13C.
Conclusions. The driving factors of these ratios within SSCs could be the IMF or fractionation effects. To further probe these effects in SSCs over time, a larger sample of SSCs must be observed spanning a larger age range.
Galaxies: starburst
Galaxies: active
ISM: molecules
Astrochemistry
Galaxies: ISM
Författare
Joshua Butterworth
Universiteit Leiden
Serena Viti
Universiteit Leiden
P. van der Werf
Universiteit Leiden
J. G. Mangum
National Radio Astronomy Observatory
S. Martin
European Southern Observatory Santiago
Atacama Large Millimeter-submillimeter Array (ALMA)
N. Harada
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Academia Sinica
K.L. Emig
National Radio Astronomy Observatory
Sebastien Muller
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
K. Sakamoto
The Graduate University for Advanced Studies (SOKENDAI)
Academia Sinica
Y. Yoshimura
University of Tokyo
Kunihiko Tanaka
Keio University
R. Herrero-Illana
European Southern Observatory Santiago
Institut de Ciències de l'Espai (ICE) - CSIC
L. Colzi
Centro de Astrobiologia (CAB)
Víctor M. Rivilla
Centro de Astrobiologia (CAB)
K. Y. Huang
Universiteit Leiden
M. Bouvier
Universiteit Leiden
E. Behrens
University of Virginia
C. Henkel
Max-Planck-Gesellschaft
King Abdulaziz University
Xinjiang Astronomical Observatory
Y. T. Yan
Max-Planck-Gesellschaft
D. S. Meier
New Mexico Institute of Mining and Technology
National Radio Astronomy Observatory Socorro
D. Zhou
Danmarks Tekniske Universitet (DTU)
University of British Columbia (UBC)
Cosmic Dawn Center (DAWN)
Universiteit Leiden
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 686 A31Ämneskategorier
Astronomi, astrofysik och kosmologi
Atom- och molekylfysik och optik
Annan fysik
DOI
10.1051/0004-6361/202348787