The first sample of spectroscopically confirmed ultra-compact massive
  galaxies in the Kilo Degree Survey
  We present results from an ongoing investigation using the Kilo Degree Survey
(KiDS) on the VLT Survey Telescope (VST) to provide a census of ultra-compact
massive galaxies (UCMGs), defined as galaxies with stellar masses $M_{\rm
\star} > 8 \times 10^{10} \rm M_{\odot}$ and effective radii $R_{\rm e} <
1.5\,\rm kpc$. UCMGs, which are expected to have undergone very few merger
events, provide a unique view on the accretion history of the most massive
galaxies in the Universe. Over an effective sky area of nearly 330 square
degrees, we select UCMG candidates from KiDS multi-colour images, which provide
high quality structural parameters, photometric redshifts and stellar masses.
Our sample of $\sim 1000$ photometrically selected UCMGs at $z < 0.5$
represents the largest sample of UCMG candidates assembled to date over the
largest sky area. In this paper we present the first effort to obtain their
redshifts using different facilities, starting with first results for 28
candidates with redshifts $z < 0.5$, obtained at NTT and TNG telescopes. We
confirmed, as bona fide UCMGs, 19 out of the 28 candidates with new redshifts.
A further 46 UCMG candidates are confirmed with literature spectroscopic
redshifts (35 at $z < 0.5$), bringing the final cumulative sample of
spectroscopically-confirmed lower-z UCMGs to 54 galaxies, which is the largest
sample at redshifts below $0.5$. We use these spectroscopic redshifts to
quantify systematic errors in our photometric selection, and use these to
correct our UCMG number counts. We finally compare the results to independent
datasets and simulations.
