Extended radio AGN at z ~ 1 in the ORELSE survey: The confining effect
  of dense environments
  Recent hydrodynamic simulations and observations of radio jets have shown
that the surrounding environment has a large effect on their resulting
morphology. To investigate this we use a sample of 50 Extended Radio Active
Galactic Nuclei (ERAGN) detected in the Observations of Redshift Evolution in
Large Scale Environments (ORELSE) survey. These sources are all successfully
cross-identified to galaxies within a redshift range of $0.55 \leq z \leq
1.35$, either through spectroscopic redshifts or accurate photometric
redshifts. We find that ERAGN are more compact in high-density environments
than those in low-density environments at a significance level of 4.5$\sigma$.
Among a series of internal properties under our scrutiny, only the radio power
demonstrates a positive correlation with their spatial extent. After removing
the possible radio power effect, the difference of size in low- and
high-density environments persists. In the global environment analyses, the
majority (86\%) of high-density ERAGN reside in the cluster/group environment.
In addition, ERAGN in the cluster/group central regions are preferentially
compact with a small scatter in size, compared to those in the cluster/group
intermediate regions and fields. In conclusion, our data appear to support the
interpretation that the dense intracluster gas in the central regions of galaxy
clusters plays a major role in confining the spatial extent of radio jets.
