Extended Radio Galaxies from large-scale surveys: from giants through pathology to cosmology

Montag, 9. September 2019, 14:00 - 15:30
Veranstaltungsort* Library
Since 2012 we pursued visual inspection of large-scale radio surveys
(including the recent VLASS and LoTSS) to compile a list of currently
10,000 extended radio galaxies (ERGs) excluding cluster haloes and
relics. For each ERG we record its host identification, redshift,
brightness, and the angular and linear extent of its radio emission,
as well as a crude morphological classification of the latter. The list
includes 1500 giant radio galaxies (GRGs) larger than 1 Mpc (i.e. six
times the number reported in literature), with a median redshift of
0.48, and including 30 quasars at redshifts from 2 to 5. However, no
trend is seen between radio size and redshift posing a problem for
standard cosmology.

I illustrate the relative ease to find new GRGs, especially with
simultaneous coverage of NVSS, FIRST, SDSS, as well as some spectacular
examples from the most recent surveys like VLASS, LoTSS and ASKAP-EMU.
I explore some statistical trends for lobe symmetry based on hotspot
positions in ~2100 radio galaxies, as well as the (mis)alignment between
radio and optical host axes. Finally, I show some promising results of
a semi-automatical approach to find remnant (or "dying") radio galaxies.


: Dr. Heinz Andernach, University of Guanajuato