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J030659.8+000824.9

Link to XCS-DR1 entry

Fig. 1: The SDSS optical image with the XCS X-ray contours overlaid.

Fig. 2: The colour-magnitude diagram used to determine the magnitude gap. Green triangles are spectroscopic cluster members and circles are photometric cluster members. Red triangles are spectroscopic non-members. Only cluster members within ±0.2 mag of the r-i colour of the fossil galaxy (dotted lines) are used to calculate the gap. The two diamonds denote the second and the fourth brightest galaxy.

Notes

This z=0.0751 system is located at 03:06:59.8 +00:08:24.9. The CMD shows an RS and both spectroscopic members lay on it. The magnitude gap is 2.5 based on SDSS photometric data and the galaxy that was excluded has a spectroscopic redshift that is ~38000 km s^-1 away from the FG. Of the four galaxies used to calculate Δm₁₄, the two that only have photometric redshifts both lie on the RS as well. The X-ray emission has T_X=2.3 keV and the peak lies ~26.2 kpc from the FG. The system is located near the edge of the SDSS footprint but at a distance of ~7.0R₂₀₀ both Δm₁₄ and L_tot are unaffected. The X-ray source is extended with R₂₀₀=1.01 Mpc or ~90R₉₀ (the largest of any system). We note that this system is an outlier in many of the plots and despite satisfying all the criteria necessary to be classified as an FS we acknowledge that this classification is uncertain. The system has a velocity dispersion of 1082 km s^-1 based on 13 galaxies.

Fossil System

Fossil Galaxy