A Gemini-NIFS view of the merger remnant NGC 34
Abstract
The merger remnant NGC 34 is a local luminous infrared galaxy (LIRG) hosting a nuclear starburst and a hard X-ray source associated with a putative, obscured Seyfert 2 nucleus. In this work, we use adaptive optics assisted near-infrared (NIR) integral field unit observations of this galaxy to map the distribution and kinematics of the ionized and molecular gas in its inner $\mathrm{1.2\, kpc \times 1.2\, kpc}$, with a spatial resolution of 70 pc. The molecular and ionized gas kinematics is consistent with a disc with projected major axis along a mean PA = -9${_{.}^{\circ}}$2 ± 0${_{.}^{\circ}}$9. Our main findings are that NGC 34 hosts an AGN and that the nuclear starburst is distributed in a circumnuclear star formation ring with inner and outer radii of ≈ 60 and 180 pc, respectively, as revealed by maps of the $\mathrm{[Fe\, {\small {II}}] / Pa\,\beta }$ and H2/Br γ emission-line ratios, and corroborated by PCA tomography analysis. The spatially resolved NIR diagnostic diagram of NGC 34 also identifies a circumnuclear structure dominated by processes related to the stellar radiation field and a nuclear region where $[\rm Fe\, {\small {II}}]$ and H2 emissions are enhanced relative to the hydrogen recombination lines. We estimate that the nuclear X-ray source can account for the central H2 enhancement and conclude that $[\rm Fe\, {\small {II}}]$ and H2 emissions are due to a combination of photoionization by young stars, excitation by X-rays produced by the AGN and shocks. These emission lines show nuclear, broad, blueshifted components that can be interpreted as nuclear outflows driven by the AGN.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2021
- DOI:
- 10.1093/mnras/stab1977
- arXiv:
- arXiv:2107.09731
- Bibcode:
- 2021MNRAS.506.4354M
- Keywords:
-
- galaxies: individual: NGC 34;
- galaxies: individual: NGC 17;
- galaxies: individual: Mrk 938;
- galaxies: ISM;
- galaxies: nuclei;
- galaxies: starburst;
- infrared: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 21 pages, 14 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal