A chemical study of carbon fractionation in external galaxies

Abstract

In the interstellar medium carbon exists in the form of two stable isotopes ${}^{12}$C and ${}^{13}$C and their ratio is a good indicator of nucleosynthesis in galaxies. However, chemical fractionation can potentially significantly alter this ratio and in fact observations of carbon fractionation within the same galaxy has been found to vary from species to species. In this paper we theoretically investigate the carbon fractionation for selected abundant carbon-bearing species in order to determine the conditions that may lead to a spread of the ${}^{12}$C/${}^{13}$C ratio in external galaxies. We find that carbon fractionation is sensitive to almost all the physical conditions we investigated, it strongly varies with time for all species but CO, and shows pronounced differences across species. Finally we discuss our theoretical results in the context of the few observations of the ${}^{12}$C/${}^{13}$C ratio in both local and higher redshift galaxies.

MNRAS, in press

References in corpus (22)

• The 2014 KIDA network for interstellar chemistry
• A 2 mm spectral line survey of the starburst galaxy NGC 253
• The evolution of CNO isotopes: a new window on cosmic star-formation history and the stellar IMF in the age of ALMA
• Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas
• Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study
• The Rest-Frame Submillimeter Spectrum of High-Redshift, Dusty, Star-Forming Galaxies
• UCLCHEM: A Gas-Grain Chemical Code
• On carbon and oxygen isotope ratios in starburst galaxies: New data from NGC253 and Mrk231 and their implications
• Abundances and Isotope Ratios in the Magellanic Clouds: The Star Forming Environment of N113
• Molecular gas heating mechanisms, and star formation feedback in merger/s tarbursts: NGC 6240 and Arp 193 as case studies
• Formation, fractionation and excitation of carbon monoxide in diffuse clouds
• Probing isotopic ratios at z = 0.89: molecular line absorption in front of the quasar PKS 1830-211
• Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A method to determine molecular gas properties in luminous galaxies
• Carbon isotopic fractionation in molecular clouds
• Molecular tracers of high mass star-formation in external galaxies
• Diagnostics of the molecular component of PDRs with mechanical heating. II: line intensities and ratios
• Ion-molecule reactions involving HCO${}^{+}$ and N${}_2$H${}^{+}$: Isotopologue equilibria from new theoretical calculations and consequences for interstellar isotope fractionation
• Spatially resolved carbon and oxygen isotopic ratios in NGC 253 using optically thin tracers
• Around the Ring We Go: The Cold, Dense Ring of Molecular Gas in NGC 1614
• Molecular transitions as probes of the physical conditions of extragalactic environments
• Isotopic ratios at z=0.68 from molecular absorption lines toward B 0218+357
• Nitrogen Fractionation in External Galaxies

Cited by in corpus (9)

• ALCHEMI: an ALMA Comprehensive High-resolution Extragalactic Molecular Inventory. Survey presentation and first results from the ACA array
• Direct measurements of carbon and sulfur isotope ratios in the Milky Way
• Starburst Energy Feedback Seen Through HCO${}^{+}$/HOC${}^{+}$ Emission in NGC 253 from ALCHEMI
• The Evolution of NGC 7465 as Revealed by its Molecular Gas Properties
• Central molecular zones in galaxies: multitransition survey of dense gas tracers HCN, HNC, and HCO+
• CHEMOUT: CHEMical complexity in star-forming regions of the OUTer Galaxy. II. Methanol formation at low metallicity
• Molecular isotopologue measurements toward super star clusters and the relation to their ages in NGC253 with ALCHEMI
• Down but not out: properties of the molecular gas in the stripped Virgo Cluster early-type galaxy NGC4526
• Seed of Life in Space (SOLIS) XI. First measurement of nitrogen fractionation in shocked clumps of the L1157 protostellar outflow