With the Westerbork Synthesis Radio Telescope, we performed HI observations of a sample of known X-ray emitting Gigahertz-peaked-spectrum galaxies with compact-symmetric-object morphology (GPS/CSOs) that lacked an HI absorption detection. We combined radio and X-ray data of the full sample of X-ray emitting GPS/CSOs and found a significant, positive correlation between the column densities of the total and neutral hydrogen ($N_{ \rm H}$ and $N_{ \rm HI}$, respectively). Using a Bayesian approach, we simultaneously quantified the parameters of the $N_{ \rm H} - N_{ \rm HI}$ relation and the intrinsic spread of the data set. For a specific subset of our sample, we found $N_{ \rm H} \propto N_{ \rm HI}^b$, with $b=0.93^{ +0.49}_{ -0.33}$, and $\sigma_{ int} (N_{ \rm H})= 1.27^{ +1.30}_{ -0.40}$. The $N_{ \rm H} - N_{ \rm HI}$ correlation suggests a connection between the physical properties of the radio and X-ray absorbing gas.
Categories: astro-ph.GA