Characterization of Two Cool Galaxy Outflow Candidates Using Mid-infrared Emission from Polycyclic Aromatic Hydrocarbons

Journal article

We characterize two candidate cool galactic outflows in two relatively low-mass, highly inclined Virgo cluster galaxies: NGC 4424 and NGC 4694. Previous analyses of observations using the Atacama Large Millimeter/submillimeter Array carbon monoxide (CO) line emission maps did not classify these sources as cool outflow hosts. Using new high-sensitivity, high-spatial-resolution, JWST mid-infrared photometry in the polycyclic aromatic hydrocarbon (PAH)–tracing F770W band, we identify extended structures present off of the stellar disk. The identified structures are bright in the MIRI F770W and F2100W bands, suggesting they include PAHs as well as other dust grains. As PAHs have been shown to be destroyed in hot, ionized gas, these structures are likely to be outflows of cool (T ≤ 104 K) gas. This work represents an exciting possibility for using mid-infrared observations to identify and measure outflows in lower-mass, lower star formation galaxies.

Authors: Sutter, J; Sandstrom, K; Chown, R; Egorov, O; Leroy, AK

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal Letters
• Volume: 992
• Issue: 1
• Article number: L7
• Publication date: 2025-10-03
• Acceptance date: 2025-09-15
• DOI: 10.3847/2041-8213/ae08b7
• EISSN: 2041-8213
• ISSN: 2041-8205
• Language: English
• Keywords: Infrared photometry; Galaxies; Interstellar medium; Polycyclic aromatic hydrocarbons