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arXiv · 2607.14971

The Goldilocks Molecule: H$_{2}$ Emission Lines Can Identify Elusive Dwarf AGN

Morgan Micharski·Chris Richardson
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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 $n_{\text{H}} \gtrsim 4.0$. This includes the case where $M_{\text{BH}} = 10^3~M_{\odot}$, 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.

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Morgan Micharski, Chris Richardson. 2026-07-16. The Goldilocks Molecule: H$_{2}$ Emission Lines Can Identify Elusive Dwarf AGN. https://arxiv.org/abs/2607.14971

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