J172010.0+263724.7
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=0.1596 system is located at
17:20:10.0 +26:37:24.7. The CMD shows an obvious RS, which all
spectroscopic members lie on, and the magnitude gap is 2.45 based on
SDSS spectroscopic data. This is close enough to 2.5 that we accept it
as an FS. The two rejected galaxies are 2400 km s-1 and
20000 km s-1 away from the FG. Reducing the spectroscopic
redshift cut to 1000 km s-1 would increase the magnitude
gap by 0.4. The X-ray temperature of the system is TX=5.5
keV and the X-ray emission peak lies ~20.2 kpc from the FG. The
system is located near the edge of the SDSS footprint but at a
distance of ~17R200 both Δm14 and
Ltot are unaffected. The X-ray source is extended with
R200=1.54 Mpc or ~30R90. This system was an
XMM target and was classified as an FS in Santos (2007). It is
also known as SDSS-C4 3072. The system has a velocity dispersion of
768 km s-1 based on 31 galaxies.
Fossil System
| XCS ID | Δm14 | R200 | LX | TX | Ltot | ΣL24 |
|---|
| XMMXCS J172010.0+263724.7 | 2.4 | 1.54 | 21.58 | 5.53 | 18.64 | 1.94 |
Fossil Galaxy
| SDSS ID | z | M∗ | Age | Z | log(SSFR) | Lgal |
|---|
| J172010.04+263732.0 | 0.1596 | 0.92 | 5.6 | 0.031 | -11.44 | 5.40 |