Deep spectroscopy in nearby galaxy clusters - III. Orbital structure of galaxies in Abell 85

Aguerri, J. A. L.; Agulli, I.; Diaferio, A.; Dalla Vecchia, C.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 468, Issue 1, p.364-377

Advertised on:
6
2017
Number of authors
4
IAC number of authors
3
Citations
18
Refereed citations
18
Description
Galaxies in clusters are strongly affected by their environment. They evolve according to several physical mechanisms that are active in clusters. Their efficiency can strongly depend on the orbital configuration of the galaxies. Our aim is to analyse the orbits of the galaxies in the cluster Abell 85, based on the study of the galaxy velocity anisotropy parameter. We have solved the Jeans equation under the assumption that the galaxies in A 85 are collisionless objects, within the spherically symmetric gravitational potential of the virialized cluster. The mass of the cluster was estimated with X-ray and caustic analyses. We find that the anisotropy profile of the full galaxy population in A 85 is an increasing monotonic function of the distance from the cluster centre: on average, galaxies in the central region (r/r200 < 0.3) are on isotropic orbits, while galaxies in the outer regions are on radial orbits. We also find that the orbital properties of the galaxies strongly depend on their stellar colour. In particular, blue galaxies are on less radial orbits than red galaxies. The different families of cluster galaxies considered here have the pseudo phase-space density profiles Q(r) and Qr(r) consistent with the profiles expected in virialized dark matter haloes in N-body simulations. This result suggests that the galaxies in A 85 have reached dynamical equilibrium within the cluster potential. Our results indicate that the origin of the blue and red colours of the different galaxy populations is the different orbital shape rather than the accretion time.
Related projects
Project Image
Numerical Astrophysics: Galaxy Formation and Evolution
How galaxies formed and evolved through cosmic time is one of the key questions of modern astronomy and astrophysics. Cosmological time- and length-scales are so large that the evolution of individual galaxies cannot be directly observed. Only through numerical simulations can one follow the emergence of cosmic structures within the current
Claudio
Dalla Vecchia
Abell 370 is located approximately 4 billion light-years away in the constellation Cetus, the Sea Monster
Galaxy Evolution in Clusters of Galaxies
Galaxies in the universe can be located in different environments, some of them are isolated or in low density regions and they are usually called field galaxies. The others can be located in galaxy associations, going from loose groups to clusters or even superclusters of galaxies. One of the foremost challenges of the modern Astrophysics is to
Jairo
Méndez Abreu
 The Invisible Scaffolding of Space
Cosmology with Large Scale Structure Probes
The Cosmic Microwave Background (CMB) contains the statistical information about the early seeds of the structure formation in our Universe. Its natural counterpart in the local universe is the distribution of galaxies that arises as a result of gravitational growth of those primordial and small density fluctuations. The characterization of the
FRANCISCO SHU
KITAURA JOYANES