The recent evidence of a peculiar distribution of X-ray sources in the elliptical galaxy NGC 4261 reported by Zezas et al. has prompted us to study this galaxy combining archive X-ray and optical observations, from Chandra, INT, and HST. We find that a sizable fraction of the X-ray sources has a globular cluster as optical counterpart. This together with the shape of the luminosity function of the X-ray sources suggest that they are accreting low-mass binaries. We further show a remarkable similarity in the anisotropy of the projected spatial distributions of the optical and X-ray sources, which leads us to conclude that the spatial anisotropy of the X-ray sources in NGC 4261 is due to the anisotropy of the globular cluster population. © 2006 International Astronomical Union.
Trinchieri, G., Giordano, L., Cortese, L., Wolter, A., Colpi, M., Gavazzi, G., et al. (2005). The trail of discrete X-ray sources in the early-type galaxy NGC 4261: Anisotropy in the globular cluster distribution. In Proceedings of the International Astronomical Union - Volume 1, Issue S230 (pp. 205-209). Cambridge University Press [10.1017/S1743921306008222].
The trail of discrete X-ray sources in the early-type galaxy NGC 4261: Anisotropy in the globular cluster distribution
CORTESE, LUCA;COLPI, MONICA;GAVAZZI, GIUSEPPE;
2005
Abstract
The recent evidence of a peculiar distribution of X-ray sources in the elliptical galaxy NGC 4261 reported by Zezas et al. has prompted us to study this galaxy combining archive X-ray and optical observations, from Chandra, INT, and HST. We find that a sizable fraction of the X-ray sources has a globular cluster as optical counterpart. This together with the shape of the luminosity function of the X-ray sources suggest that they are accreting low-mass binaries. We further show a remarkable similarity in the anisotropy of the projected spatial distributions of the optical and X-ray sources, which leads us to conclude that the spatial anisotropy of the X-ray sources in NGC 4261 is due to the anisotropy of the globular cluster population. © 2006 International Astronomical Union.
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