...${\ge}1$ Mpc

For consistency with numerous papers on GRGs (e.g. Schoen-makers et al. 2000c,a,1999; Lara et al. 2001; Kaiser et al. 2000; Schoen-makers et al. 2000b) H₀=50 km s^-1 Mpc^-1 and q₀=0.5 is used throughout this paper. For these cosmological parameters the redshift value of z=1.25provides the maximum linear size for a given angular size: $1\hbox{$^{\prime\prime}$ }$corresponds to 8.6 kpc.

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...(White et al. 1997)

Official website: http://sundog.stsci.edu

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... spectra

Obviously, calculation of the spectral indices of the "cores'' alone was not possible because of the resolution limit of the GB6 survey.

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... (SDSS/DR4)

This is the most recent release at the time of writing.

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... expected

Consequently, well-aligned DDRGs should be exceptional. However, Liu et al. (2003) point out that if the mass ratio of the two merging black holes is in the range 0.01 to 0.4, realignment of the central engine and the subsequent formation of an X-shaped radio structure are not inevitable, and so the above-mentioned speculation that DDRGs can be regarded as "zero-misalignment'' X-shaped sources could still be a viable scenario.

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