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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Sloshing in its cD halo: MUSE kinematics of the central galaxy NGC 3311 in the Hydra I cluster

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Barbosa, C. E. [1] ; Arnaboldi, M. [2, 3] ; Coccato, L. [2] ; Gerhard, O. [4] ; Mendes de Oliveira, C. [1] ; Hilker, M. [2] ; Richtler, T. [5]
Total Authors: 7
[1] Univ Sao Paulo, IAG, Dept Astron, Rua Matao 1226, Sao Paulo, SP - Brazil
[2] European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching - Germany
[3] INAF, Osservatorio Astron Torino, STr Osservatorio 20, I-10025 Pino Torinese - Italy
[4] Max Planck Inst Extraterr Phys, Giessenbachstr, D-85741 Garching - Germany
[5] Univ Concepcion, Dept Astron, Concepcion - Chile
Total Affiliations: 5
Document type: Journal article
Source: Astronomy & Astrophysics; v. 609, JAN 11 2018.
Web of Science Citations: 6

Context. Early-type galaxies (ETGs) show a strong size evolution with redshift. This evolution is explained by fast ``in-situ{''} star formation at high-z followed by a late mass assembly mostly driven by minor mergers that deposit stars primarily in the outer halo. Aims. We aim to identify the main structural components of the Hydra I cD galaxy NGC 3311 to investigate the connection between the central galaxy and the surrounding stellar halo. Methods. We produce maps of the line-of-sight velocity distribution (LOSVD) moments from a mosaic of MUSE pointings covering NGC 3311 out to 25 kpc. Combining deep photometric and spectroscopic data, we model the LOSVD maps using a finite mixture distribution, including four non-concentric components that are nearly isothermal spheroids, with di ff erent line-of-sight systemic velocities V, velocity dispersions sigma, and small (constant) values of the higher order Gauss-Hermite moments h(3) and h(4). Results. The kinemetry analysis indicates that NGC 3311 is classified as a slow rotator, although the galaxy shows a line-of-sight velocity gradient along the photometric major axis. The comparison of the correlations between h(3) and h(4) with V/sigma with simulated galaxies indicates that NGC 3311 assembled mainly through dry mergers. The sigma profile rises to similar or equal to 400 km s(-1) at 20 kpc, a significant fraction (0.55) of the Hydra I cluster velocity dispersion, indicating that stars there were stripped from progenitors orbiting in the cluster core. The finite mixture distribution modeling supports three inner components related to the central galaxy and a fourth component with large e ff ective radius (51 kpc) and velocity dispersion (327 km s(-1)) consistent with a cD envelope. We find that the cD envelope is o ff set from the center of NGC 3311 both spatially (8.6 kpc) and in velocity (Delta V = 204 km s(-1)), but coincides with the cluster core X-ray isophotes and the mean velocity of core galaxies. Also, the envelope contributes to the broad wings of the LOSVD measured by large h(4) values within 10 kpc. Conclusions. The cD envelope of NGC 3311 is dynamically associated with the cluster core, which in Hydra I is in addition displaced from the cluster center, presumably due to a recent subcluster merger. (AU)

FAPESP's process: 11/21325-0 - Kinematics and stellar populations of nearby groups
Grantee:Carlos Eduardo Barbosa
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 09/54202-8 - Acquisition of a robotic telescope for the Brazilian astronomical community
Grantee:Claudia Lucia Mendes de Oliveira
Support type: Multi-user Equipment Program
FAPESP's process: 16/12331-0 - Galaxy evolution in different environments using spatially resolved kinematics and stellar populations
Grantee:Carlos Eduardo Barbosa
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 16/17119-9 - The study of galaxies in groups with SAM-FP and T80-south and the construction of the ABRAS T-100 telescope
Grantee:Claudia Lucia Mendes de Oliveira
Support type: Regular Research Grants