João P V Benedetti, Rogério Riffel, Tiago Ricci, Rogemar A Riffel, Miriani Pastoriza, Marina Trevisan, Luis G Dahmer-Hahn, Daniel Ruschel-Dutra, Alberto Rodríguez-Ardila, Anna Ferré-Mateu, Alexandre Vazdekis, João Steiner
{"title":"Digging deeper into NGC 6868 II: ionized gas and excitation mechanism","authors":"João P V Benedetti, Rogério Riffel, Tiago Ricci, Rogemar A Riffel, Miriani Pastoriza, Marina Trevisan, Luis G Dahmer-Hahn, Daniel Ruschel-Dutra, Alberto Rodríguez-Ardila, Anna Ferré-Mateu, Alexandre Vazdekis, João Steiner","doi":"10.1093/mnras/stae2077","DOIUrl":null,"url":null,"abstract":"We studied the ionized gas in the inner region (∼680 × 470 pc2) of the galaxy NGC 6868 using Gemini/GMOS 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 (σ ∼ 110 km s−1) tracing an ionized gas disc and a broad component (σ ∼ 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 ∼14000 K in the central region to ≳ 20000 K with an outward increasing temperature gradient. The electron density map exhibits an inverse relationship, with central values reaching Ne ∼ 4000 cm-3 for the broad component decreasing to Ne ∼ 100 cm-3 towards the edges of the field of view. Using BPT diagrams, we found that all spaxels are consistent with both 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 ionisation 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.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"9 1","pages":""},"PeriodicalIF":4.7000,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Monthly Notices of the Royal Astronomical Society","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1093/mnras/stae2077","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
We studied the ionized gas in the inner region (∼680 × 470 pc2) of the galaxy NGC 6868 using Gemini/GMOS 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 (σ ∼ 110 km s−1) tracing an ionized gas disc and a broad component (σ ∼ 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 ∼14000 K in the central region to ≳ 20000 K with an outward increasing temperature gradient. The electron density map exhibits an inverse relationship, with central values reaching Ne ∼ 4000 cm-3 for the broad component decreasing to Ne ∼ 100 cm-3 towards the edges of the field of view. Using BPT diagrams, we found that all spaxels are consistent with both 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 ionisation 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.
期刊介绍:
Monthly Notices of the Royal Astronomical Society is one of the world''s leading primary research journals in astronomy and astrophysics, as well as one of the longest established. It publishes the results of original research in positional and dynamical astronomy, astrophysics, radio astronomy, cosmology, space research and the design of astronomical instruments.