HST /WFC3 OBSERVATIONS OF AN OFF-NUCLEAR SUPERBUBBLE IN ARP 220

Kelly Lockhart , Lisa Kewley (1) , Jessica Lu , Mark Allen (2) , David Rupke , Daniela Calzetti (3) , Richard Davies , Michael Dopita , Hauke Engel , Timothy Heckman , Claus Leitherer , David Sanders

1 RSAA - Research School of Astronomy and Astrophysics [Canberra]
2 ObAS - Observatoire astronomique de Strasbourg
3 UMass Amherst - University of Massachusetts [Amherst]

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 Hα+[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 ∼100 pc of the nuclei are favored based on the alignment of the bubble and energetics arguments.

Domaines: Astrophysique [astro-ph]

Kelly Lockhart, Lisa Kewley, Jessica Lu, Mark Allen, David Rupke, et al.. HST /WFC3 OBSERVATIONS OF AN OFF-NUCLEAR SUPERBUBBLE IN ARP 220. The Astrophysical Journal, 2015, 810 (2), pp.149. ⟨10.1088/0004-637X/810/2/149⟩. ⟨hal-02387861⟩