Astrophys. J., Suppl. Ser., 195, 15 (2011/August-0)
The luminosity profiles of brightest cluster galaxies.
DONZELLI C.J., MURIEL H. and MADRID J.P.
Abstract (from CDS):
We have derived detailed R-band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 mag/arcsec2. Light profiles were initially fitted with a Sérsic's R 1/n model, but we found that 205 (∼48%) BCGs require a double component model to accurately match their light profiles. The best fit for these 205 galaxies is an inner Sérsic model, with indices n ∼ 1-7, plus an outer exponential component. Thus, we establish the existence of two categories of the BCG luminosity profiles: single and double component profiles. We found that double profile BCGs are brighter (∼0.2 mag) than single profile BCGs. In fact, the Kolmogorov-Smirnov test applied to these subsamples indicates that they have different total magnitude distributions, with mean values MR= -23.8±0.6 mag for single profile BCGs and MR = -24.0±0.5 mag for double profile BCGs. We find that partial luminosities for both subsamples are indistinguishable up to r = 15 kpc, while for r > 20 kpc the luminosities we obtain are on average 0.2 mag brighter for double profile BCGs. This result indicates that extra-light for double profile BCGs does not come from the inner region but from the outer regions of these galaxies. The best-fit slope of the Kormendy relation for the whole sample is a = 3.13 ±0.04. However, when fitted separately, single and double profile BCGs show different slopes: asingle= 3.29±0.06 and adouble= 2.79±0.08. Also, the logarithmic slope of the metric luminosity α is higher in double profile BCGs (αdouble= 0.65±0.12) than in single profile BCGs (αsingle= 0.59±0.14). The mean isophote outer ellipticity (calculated at µ ∼ 24 mag/arcsec2) is higher in double profile BCGs (edouble= 0.30±0.10) than in single profile BCGs (esingle= 0.26 ±0.11). Similarly, the mean absolute value of inner minus outer ellipticity is also higher in double profile BCGs. From a subsample of 24 BCGs, we found strong evidence that extra-light at intermediate radii in double profile BCGs is related to the presence of a faint stellar envelope. Similarly, from another subsample of 12 BCGs we also found that extra-light is related to star formation. On the other hand, we did not find differences between these two BCG categories when we compared global cluster properties such as the BCG-projected position relative to the cluster X-ray center emission, X-ray luminosity, or BCG orientation with respect to the cluster position angle.
galaxies: clusters: general - galaxies: elliptical and lenticular, cD - galaxies: interactions
VizieR on-line data:
<Available at CDS (J/ApJS/195/15): table2.dat>
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