COMP2CAT: hunting compact double radio sources in the local Universe

We present a catalog of compact double radio galaxies (hereafter COMP2$CAT$) listing 43 edge-brightened radio sources whose projected linear size does not exceed 60 kpc, the typical size of their host galaxies. This is the fifth in a series of radio source catalogs recently created, namely: FRI$CAT$, FRII$CAT$, FR0$CAT$ and WAT$CAT$, each focused on a different class of radio galaxies. The main aim of our analysis is to attain a better understanding of sources with intermediate morphologies between FR\,IIs and FR\,0s. COMP2$CAT$ sources were selected from an existing catalog of radio sources based on NVSS, FIRST and SDSS observations for having, mainly, i) edge-brightened morphologies, typical of FR\,IIs, ii) redshifts $z < 0.15$ and iii) projected linear sizes smaller than 60 kpc. With radio luminosities at 1.4 GHz $10^{38} \lesssim L_{1.4} \lesssim 10^{41}$ erg s$^{-1}$, COMP2$CAT$ sources appear as the low radio luminosity tail of FR\,IIs. However, their host galaxies are indistinguishable from those of large-scale radio sources: they are luminous ($-21 \gtrsim M_{r} \gtrsim -24$), red, early-type galaxies with black hole masses in the range of $10^{7.5} \lesssim M_{\rm BH} \lesssim 10^{9.5}\, \rm{M}_\odot$. Moreover, all but one of the COMP2$CAT$ sources are optically classifiable as low excitation radio galaxies, in agreement with being the low radio-power tail of FR\,Is and FR\,IIs. This catalog of compact double sources, which is $\sim 47 \%$ complete at $z<0.15$, can potentially be used to clarify the role of compact double sources in the general evolutionary scheme of radio galaxies.