Speaker
Description
Giant Radio Galaxies (GRGs) with a projected linear extent $>$0.7 Mpc were first found in 1974 and over 10,000 are now known. I present results based on my compilation of GRGs (a) from literature, and my visual inspection of (b) large-scale radio surveys in general (e.g. NVSS, SUMSS, RACS, LoTSS DR2, etc.) with $\sim$9,800 GRGs, and of specific regions like (c) the LoTSS Deep Fields (247 GRGs), as well as (d) the SWAG-X/eFEDS/LOFAR field with 308 GRGs. I find that a systematic visual inspection provides a higher ratio of GRGs $<$1 Mpc to those $>$1 Mpc than literature samples, which tend to disfavor smaller GRGs. This ratio, as well as the details of the cumulative angular and linear size distributions vary with GRG sample used, likely in part due to survey characteristics, but potentially due to cosmic variance. I also show examples of published mis-identifications based on automated algorithms, lacking the necessary human control of ML results. In order to shed light on the open question why GRGs can reach their large sizes, I use a sample of 115 extreme GRGs larger than 3 Mpc, and investigate properties like how they were discovered (mostly by LOFAR), their redshift and radio luminosity distribution, and bending angle, and compare these with GRGs of modest sizes.