The Goldilocks Molecule: H 2 Emission Lines Can Identify Elusive Dwarf AGN
Morgan Micharski, Chris Richardson
astro-ph.GA
Submitted: 2026-07-16
Comments: Accepted to RNAAS
License: http://creativecommons.org/licenses/by/4.0/
The gist: We propose using H 2 emission lines as a novel diagnostic to identify dwarf AGN by running photoionization models incorporating active intermediate-mass black holes and using an observed WISE dwarf
Terminology
Abstract
We propose using H 2 emission lines as a novel diagnostic to identify dwarf AGN by running photoionization models incorporating active intermediate-mass black holes and using an observed WISE dwarf AGN as a template. Though many dwarf AGN would be incorrectly classified as star-forming if the H 2 2.12 mu m/Br gamma ratio is used, ratios between H 2 emission lines can reveal active IMBHs in cases where log n H 4.0. This includes the case where M BH = 10 3 M, even though the optical strong lines and NIR coronal lines would likely go undetected. We conclude that H 2 emission lines show promise in detecting the most elusive IMBHs.
Sources
- Near-infrared diagnostic diagrams of the gas ionization sources in nearby galaxies: a JWST NIRSpec view
- The 2017 Release of Cloudy
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