Open AccessStudying the asymmetry of the globular cluster population of NGC 4261
Author(s) -
Bonfini P.,
Zezas A.,
Birkinshaw M.,
Worrall D. M.,
Fabbiano G.,
O’Sullivan E.,
Trinchieri G.,
Wolter A.
Publication year - 2012
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2012.20514.x
Subject(s) - physics , globular cluster , astrophysics , asymmetry , astronomy , galaxy , elliptical galaxy , population , surface brightness , hubble sequence , luminosity , galaxy cluster , lenticular galaxy , quantum mechanics , demography , sociology
We present an analysis of the globular cluster (GC) population of the elliptical galaxy NGC 4261 based on Hubble Space Telescope Wide Field Planetary Camera 2 data in the B , V and I bands. We study the spatial distribution of the GCs in order to probe the anisotropy in the azimuthal distribution of the discrete X‐ray sources in the galaxy revealed by Chandra images. The luminosity function of our GC sample (complete at the 90 per cent level for m V = 23.8 mag) peaks at m V = 25.1 mag, which corresponds to a distance consistent with previous measurements. The colour distribution can be interpreted as being the superposition of a blue and red GC component with average colours V − I = 1.01 mag and 1.27 mag, respectively. This is consistent with a bimodal colour distribution typical of elliptical galaxies. The red GC’s radial profile is steeper than that of the galaxy surface brightness, while the profile of the blue subpopulation looks more consistent with it. The most striking finding is the significant asymmetry in the azimuthal distribution of the GC population about a north‐east–south‐west (NE–SW) direction. The lack of any obvious feature in the morphology of the galaxy suggests that the asymmetry could be the result of an interaction or a merger.