Testing the two planes of satellites in the Centaurus group

Müller, Oliver and Jerjen, Helmut and Pawlowski, Marcel S. and Binggeli, Bruno. (2016) Testing the two planes of satellites in the Centaurus group. Astronomy and Astrophysics, 595. A119.

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Official URL: http://edoc.unibas.ch/53898/

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Context. The existence of satellite galaxy planes poses a major challenge for the standard picture of structure formation with non-baryonic dark matter. Recently Tully et al. (2015, ApJ, 802, L25) reported the discovery of two almost parallel planes in the nearby Cen A group using mostly high-mass galaxies (M B < -10 mag) in their analysis. Aims: Our team detected a large number of new group member candidates in the Cen A group. This dwarf galaxy sample, combined with other recent results from the literature, enables us to test the galaxy distribution in the direction of the Cen A group and to determine the statistical significance of the geometric alignment. Methods: Taking advantage of the fact that the two galaxy planes lie almost edge-on along the line of sight, the newly found group members can be assigned relative to the two planes. We used various statistical methods to test whether the distribution of galaxies follows a single normal distribution or shows evidence of bimodality as has been reported earlier. Results: We confirm that the data used for the Tully et al. study support the picture of a bimodal structure. When the new galaxy samples are included, however, the gap between the two galaxy planes is closing and the significance level of the bimodality is reduced. Instead, the plane that contains Cen A becomes more prominent. Conclusions: We found evidence that the galaxy system around Cen A is made up of only one plane of satellites. This plane is almost orthogonal to the dust plane of Cen A. Accurate distances to the new dwarf galaxies will be required to measure the precise 3D distribution of the galaxies around Cen A.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Astrophysik (Thielemann)
UniBasel Contributors:Binggeli, Bruno and Müller, Olivier
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:EDP Sciences
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Mar 2017 08:07
Deposited On:20 Feb 2017 13:21

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