Gas and stellar dynamics in Stephan’s Quintet

M Yttergren,Á Sánchez-Monge,T Peitl-Thiesen,A Zensus,A Eckart,M Valencia-S,P Misquitta

doi:10.1051/0004-6361/202040188

Abstract

In nearby compact galaxy groups we can study the complex processes of galaxy interactions at high resolution and obtain a window into a time in the history of the Universe when the galaxies were closely spaced and the intergalactic medium was awash with gas. Stephan’s Quintet is a nearby compact galaxy group and a perfect laboratory for studying the process of galaxy evolution through galaxy harassment and interaction. By analysing the kinematics of Stephan’s Quintet we aim to provide an increased understanding of the group, the history of the interactions, their cause and effect, and the details regarding the physical processes occurring as galaxies interact. Ionised gas and stellar kinematics have been studied using data from the Large Binocular Telescope, while the molecular gas kinematics have been obtained from CO observations using the IRAM 30m telescope. Large areas of the group have been mapped and analysed. We obtain a total ionised gas mass in the regions chosen for closer analysis of 20.1 ± 0.2 ⋅ 1010 M⊙ and a total H2 gas mass of 21 ± 2 ⋅ 109 M⊙ in the observed area (spectra integrated over the velocity range covering Stephan’s Quintet), while the star-forming clouds show an impressive complexity, with gas congregations at multiple velocities at many locations throughout the group. We map the large-scale nuclear wind in NGC7319 and its decoupled gas and stellar disk. With our high resolution data we can, for the first time, reveal the Seyfert 1 nature of NGC7319 and fit the narrow-line region and broad-line region of the Hα line. While the 12CO (1 − 0) map shows significant emission in the area in or near NGC7319, the bridge, and the star-forming ridge, the 12CO (2 − 1) emission shows a prevalence to the star-forming ridge, an area south of the NGC7318 pair, and shows an extension towards NGC7317 – connecting NGC7317 to the centre of the group, indicating a previous interaction. NGC7317 may also be a prime candidate for studies of the process of galaxy harassment. Furthermore, we connect the kinematical structures in Stephan’s Quintet to the history of the group and the ongoing interaction with NGC7318B. Through our extensive observations of Stephan’s Quintet we trace and present the kinematics and evolution of the complex processes and structures occurring in this nearby interactive group.

Highlights

In the early Universe, the close proximity between galaxies is expected to have enabled a high rate of galaxy interactions and mergers (Rodríguez-Baras et al 2014), which were vital in driving galaxy evolution
In nearby compact galaxy groups we can study the complex processes of galaxy interactions at high resolution and obtain a window into a time in the history of the Universe when the galaxies were closely spaced and the intergalactic medium was awash with gas
By analysing the kinematics of Stephan’s Quintet we aim to provide an increased understanding of the group, the history of the interactions, their cause and effect, and the details regarding the physical processes occurring as galaxies interact

Summary

Introduction

In the early Universe, the close proximity between galaxies is expected to have enabled a high rate of galaxy interactions and mergers (Rodríguez-Baras et al 2014), which were vital in driving galaxy evolution. Lisenfeld et al (2002) and Guillard et al (2012) both used an IRAM 30m single pointing of region SQ-A (the position of SQ-A is marked in Fig. 2) to obtain the 12CO (1−0) spectrum; though they have emission at similar line-of-sight velocities, Guillard et al (2012) show an amplitude a factor of ∼5 larger than Lisenfeld et al (2002). We find duality in the velocity component in the [OIII] line, as illustrated, which indicates that the gas is on more than one congregation (supported by the fits of the regions, values presented in the table in Appendix G.1) We find duality in the velocity component in the [OIII] line, as illustrated in Fig. 16, which indicates that the gas is on more than one congregation (supported by the fits of the regions, values presented in the table in Appendix G.1)

Revealing the Seyfert 1 nature

The molecular gas content

Findings

Summary and conclusions