HST/WFC3 Observations of an Off-Nuclear Superbubble in Arp 220

Abstract

We present a high spatial resolution optical and infrared study of the circumnuclear region in Arp 220, a late-stage galaxy merger. Narrowband imaging using HST/WFC3 has resolved the previously observed peak in H$\alpha$+[NII] emission into a bubble-shaped feature. This feature measures 1.6" in diameter, or 600 pc, and is only 1" northwest of the western nucleus. The bubble is aligned with the western nucleus and the large-scale outflow axis seen in X-rays. We explore several possibilities for the bubble origin, including a jet or outflow from a hidden active galactic nucleus (AGN), outflows from high levels of star formation within the few hundred pc nuclear gas disk, or an ultraluminous X-ray source. An obscured AGN or high levels of star formation within the inner $\sim$100 pc of the nuclei are favored based on the alignment of the bubble and energetics arguments.

Accepted for publication in ApJ. 12 pages, 10 figures

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Cited by in corpus (9)

• A Review of Recent Observations of Galactic Winds Driven by Star Formation
• Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz: A kpc-scale star forming disk surrounding nuclei with shocked outflows
• MUSE view of Arp220: Kpc-scale multi-phase outflow and evidence for positive feedback
• PdBI U/LIRG Survey (PULS): Dense Molecular Gas in Arp 220 and NGC 6240
• No evidence of AGN features in the nuclei of Arp 220 from JWST/NIRSpec IFS
• JWST/NIRSpec insights into the circumnuclear region of Arp 220: A detailed kinematic study
• Arp 220: A Post-Starburst Galaxy With Little Star Formation Outside of It's Nuclear Disks
• Hadronic Interactions of Energetic Charged Particles in Protogalactic Outflow Environments and Implications for the Early Evolution of Galaxies
• The OH Megamaser Emission in Arp\,220: the rest of the story