Year: 2024
Type: article
Abstract: ABSTRACT We studied the ionized gas in the inner region ($\sim$$680\times 470$ pc2) of the galaxy NGC 6868 using Gemini/GMOS (Gemini Multi-Object Spectrograph) integral field unit observations. Channel maps reveal complex kinematics and morphology, indicating multiple processes at work in NGC 6868. Through emission-line fitting, we identified two ubiquitous components in our data: a narrow ($\sigma \sim 110$ km s$^{-1}$) tracing an ionized gas disc and a broad component ($\sigma \sim 300$ km s$^{-1}$) mainly associated with inflowing/outflowing gas. The derived V-band reddening shows a spatial distribution consistent with that obtained from stellar population synthesis, although with generally higher values. For the first time, we measured the electron temperature in NGC 6868, finding values ranging from $\sim$14 000 K in the central region to $\gtrsim 20000$ K with an outward increasing temperature gradient. The electron density map exhibits an inverse relationship, with central values reaching $N_e\sim 4000$ cm–3 for the broad component decreasing to $N_e\sim 100$ cm–3 towards the edges of the field of view. Using BPT diagrams, we found that all spaxels are consistent with both active galactic nucleus (AGN) and shock ionization. However, when this information is combined with our kinematic and temperature findings, and further supported by the WHAN diagram, we argue that an AGN is the dominant ionization mechanism in the central region of NGC 6868, while the extended outer component is ionized by a combination of hot low-mass evolved stars and shocks. According to our findings, shocks play a significant role in the ionization balance of this galaxy.
Institutions: Universidade Federal do Rio Grande do Sul, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Universidade Federal de Santa Maria, Universidade Federal da Fronteira Sul, Chinese Academy of Sciences, Shanghai Astronomical Observatory, Universidade Federal de Santa Catarina, Laboratório Nacional de Astrofísica, Universidade de São Paulo
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,012
Funders: National Science Foundation, L'Oreal USA, National Natural Science Foundation of China, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Korea Astronomy and Space Science Institute, Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, Universidade Federal do Rio Grande do Sul, Ministério da Ciência, Tecnologia, Inovações e Comunicações, Fundación Bancaria Caixa d'Estalvis i Pensions de Barcelona, Agencia Nacional de Investigación y Desarrollo, Agencia Estatal de Investigación, National Key Research and Development Program of China
Awards: G1508652653, G1629335119, Geospace Environment Modeling (GEM): Simulation Studies of Substorm Triggering Processes, G2262748287, G2326806532, G2666758299, G2823776494, G284932921, G2974678343, G3102226075, G3480869486, G3558378898, G3803561910, G4024920341, G425668148, G4436499426, G4631820474, G5132640529, G586324143, G611330818, G6248797101, G6360782017, G6508009332, G6610068917, G6614004076, Planning Grant for CPPR/NSF Center, G6825622554, G7084143925, G7300083417, G742102471, G7685134749, G8738365817, G8814802082, G969947816
OpenAlex ID: W4402288938