Extended Radio AGN at z ∼ 1 in the ORELSE Survey: The Confining Effect of Dense Environments

October 2020 • 2020ApJ...902..101S

Authors • Shen, Lu • Liu, Guilin • Zhang, Meng-Fei • Lemaux, Brian C. • Lubin, Lori M. • Pelliccia, Debora • Moravec, Emily • Golden-Marx, Emmet • Zhou, Hongyan • Fang, Wenjuan • Tomczak, Adam • McKean, John • Miller, Neal A. • Fassnacht, Christopher D. • Wu, Po-Feng • Kocevski, Dale • Gal, Roy • Hung, Denise • Squires, Gordon

Abstract • 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 survey. These sources are all successfully cross-identified to galaxies within a redshift range of 0.55 ≤ z ≤ 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 4.5σ. 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.

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Gordon Squires

Senior Scientist