A Giant Metrewave Radio Telescope search for associated HI 21 cm absorption in GHz-peaked-spectrum sources

We report the first detections of associated HI 21 cm absorption in Gigahertz-peaked-spectrum (GPS) sources at high redshifts, z > 1, using the Giant Metrewave Radio Telescope (GMRT). Our GMRT search for associated H-I 21 cm absorption in a sample of 12 GPS sources yielded two new detections of absorption, towards TXS 1200+ 045 at z = 1.226 and TXS 1245-197 at z= 1.275, and five non-detections. These are only the sixth and seventh detections of associated HI 21 cm absorption in active galactic nuclei (AGNs) at z > 1. Both HI 21 cm absorption profiles are wide, with velocity spans between nulls of approximate to 600 km s(-1) (TXS 1200+ 045) and approximate to 1100 km s(-1) (TXS 1245-197). In both absorbers, the large velocity spread of the absorption and its blueshift from the AGN suggest that it arises in outflowing neutral gas, perhaps driven by the radio jets to high velocities. We derive mass outflow rates of. M approximate to 32M(circle dot) yr(-1) (TXS 1200+ 045) and. M approximate to 18M(circle dot) yr(-1) (TXS 1245-197), comparable to the mass outflow rates seen earlier in low-redshift AGNs.