Abstract

The heavy element content (“metallicity”) of the Universe is a record of the total star formation history. Gas-phase metallicity in galaxies, as well as its evolution with time, is of particular interest as a tracer of accretion and outflow processes. However, metallicities from the widely-used electron temperature (Te) method are typically ∼ 2× lower than the values based on the recombination line method. This “abundance discrepancy factor” (ADF) is well known and is commonly ascribed to bias due to temperature fluctuations. We present a measurement of oxygen abundance in the nearby (3.4 Mpc) system, Mrk 71, using a combination of optical and far-IR emission lines to measure and correct for temperature fluctuation effects. Our far-IR result is inconsistent ( > 2σ significance) with the metallicity from recombination lines and instead indicates little to no bias in the standard Te method, ruling out the long-standing hypothesis that the ADF is explained by temperature fluctuations for this object. Our results provide a framework to accurately measure metallicity across cosmic history, including with recent data reaching within the first billion years with JWST and the Atacama Large Millimeter Array (ALMA).

Document Type

Article

Publication Date

2023

Notes/Citation Information

Springer Nature 2021

Digital Object Identifier (DOI)

https://doi.org/10.1038/s41550-023-01953-7

Funding Information

Financial support for this work was provided by NASA through award #08 0071 issued by USRA. R.S. acknowledges the support by NASA through the NASA Hubble Fellowship grant #HST-HF2-51469.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. J.Sutter gratefully acknowledges funding from STScI grant JWST-GO-02107.006.A. R.M. acknowledges support of the NRAO. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc

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