The origin of the cold gas in central galaxies in groups is still a matter of debate. We present Multi-Unit Spectroscopic Explorer (MUSE) observations of 18 optically selected local (z ≤ 0:017) brightest group galaxies (BGGs) to study the kinematics and distribution of the optical emission-line gas. MUSE observations reveal a distribution of gas morphologies including ten complex networks of filaments extending up to ∼10 kpc to two compact (<3 kpc) and five extended (>5 kpc) disk-dominated structures. Some rotating disks show rings and elongated structures arising from the central disk. The kinematics of the stellar component is mainly rotationdominated, which is very different from the disturbed kinematics and distribution found in the filamentary sources. The ionized gas is kinematically decoupled from the stellar component for most systems, suggesting an external origin for the gas. We also find that the Hα luminosity correlates with the cold molecular gas mass. By exploring the thermodynamical properties of the X-ray atmospheres, we find that the filamentary structures and compact disks are found in systems with small central entropy values, K, and tcool=teddy ratios. This suggests that, similar to brightest cluster galaxies (BCGs) in cool core clusters, the ionized filaments and the cold gas associated to them are likely formed from hot halo gas condensations via thermal instabilities, which is consistent with the chaotic cold accretion simulations (as shown via the C ratio, Tat, and k plot). We note that the presence of gaseous rotating disks is more frequent than in BCGs. An explanation for the origin of the gas in those objects is a contribution to gas fueling by wet mergers or group satellites, as qualitatively hinted at by some sources of the present sample. Nonetheless, we discuss the possibility that some extended disks could also be a transition stage in an evolutionary sequence including filaments, extended disks, and compact disks, as described by hot gas condensation models of cooling flows.
|Journal||Astronomy and Astrophysics|
|State||Published - Oct 1 2022|
Bibliographical noteFunding Information:
This work was supported by the ANR grant LYRICS (ANR-16-CE31-0011). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 097.A-0366(A), and/or data products created thereof. M.G. acknowledges partial support by NASA Chandra GO9-20114X and HST GO-15890.020/023-A. E.O’S. acknowledges support from NASA through XMM-Newton award 80NSSC19K1056. P.L. (contract DL57/2016/CP1364/CT0010) is supported by national funds through Fundação para a Ciência e Tecnologia (FCT) and the Centro de Astrofísica da Universidade do Porto (CAUP).
This work was supported by the ANR grant LYRICS (ANR-16-CE31-0011). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 097.A-0366(A), and/or data products created thereof. M.G. acknowledges partial support by NASA Chandra GO9-20114X and HST GO-15890.020/023-A. E.O'S. acknowledges support from NASA through XMM-Newton award 80NSSC19K1056.
© V. Olivares et al. 2022.
- Galaxies: Clusters: Intracluster medium
- Galaxies: Groups: General
- Galaxies: Kinematics and dynamics
- Methods: Observational
- Techniques: Imaging spectroscopy
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science