RX J2129.7+0005 BCG is one of the
largest galaxies with a
diameter exceeding 500,000 light-years across. It is found optically
luminous[3] and is aligned with its cluster distribution, suggesting that the galaxy lies at the bottom of the cluster's
gravitational potential.[4] It has a central
velocity dispersions between the range of α ~ 300–400 km s−1[5][6] and little
rotational support. Like other elliptical galaxies, RX J2129.7+0005 BCG has a light profile described by the de Vaucouleurs
surface brightness law, μ(r) α r1/4, over a large range in
radius.[7] It is known to have an extended envelope of excess
light, according to the
de Vaucouleurs law fitted within the inner regions.[8] As for intracluster light in RX J2129.7+0005 BCG on the other hand, it is estimated to have a range from 27.5 mag arcsec-2 at 100 kpc to ~32 mag arcsec-2 at 700 kpc as observed by
r-bands.[9]
It is possible RX J2129.7+0005 BCG was formed from smaller
spiral or elliptical galaxies.[10] As they collided with each other,
dynamical friction together with
tidal forces redistribute ordered orbital kinetic energy into random energy forms, allowing these galaxies to merge into an amorphous, triaxial system resembling the appearance of an elliptical galaxy.[11]
Apart from that, RX J2129+0005 BCG is classified an
active galaxy with an
X-ray bright nucleus[12] and a low-excitation
radio galaxy with a 1.4 GHz luminosity range between the values of 2 × 1023 and 3 × 1025 W
Hz−1.[13][14] Its radio power in RX J2129.7+0005 detected, is found in the range of 2 ×1023 to ~ 1026 W Hz−1 and radio
spectral indices α 1.530 and also distributed from ~ -1 to -0.25 around the central value < α > =-0.68 with a resolved radio emission.[15]