The nuclear properties and extended morphologies of powerful radio galaxies: the roles of host galaxy and environment

H. Miraghaei, P. N. Best

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Powerful radio Galaxies exist as either compact or extended sources,with the extended sources traditionally classified by their radiomorphologies as Fanaroff-Riley (FR) type I and II sources. FRI/FRII andcompact radio galaxies have also been classified by their opticalspectra into two different types: high excitation (HERG; quasar-mode)and low excitation (LERG; jet-mode). We present a catalogue of visualmorphologies for a complete sample of >1000 1.4-GHz-selected extendedradio sources from the Sloan Digital Sky Survey. We study theenvironment and host galaxy properties of FRI/FRII and compact sources,classified into HERG/LERG types, in order to separate and distinguishthe factors that drive the radio morphological variations from thoseresponsible for the spectral properties. Comparing FRI LERGs with FRIILERGs at fixed stellar mass and radio luminosity, we show that FRIstypically reside in richer environments and are hosted by smallergalaxies with higher mass surface density; this is consistent withextrinsic effects of jet disruption driving the Fanaroff-Riley (FR)dichotomy. Using matched samples of HERGs and LERGs, we show that HERGhost galaxies are more frequently star forming, with more evidence fordisc-like structure than LERGs, in accordance with currently favouredmodels of fundamentally different fuelling mechanisms. ComparingFRI/FRII LERGs with compact LERGs, we find the primary difference isthat compact objects typically harbour less massive black holes. Thissuggests that lower mass black holes may be less efficient at launchingstable radio jets, or do so for shorter times. Finally, we investigaterarer sub-classes: wide-angle-tailed, head-tail, FR-hybrid anddouble-double sources.
Original languageEnglish
Pages (from-to)4346-4363
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 5 Jan 2017

Keywords / Materials (for Non-textual outputs)

  • galaxies: active
  • galaxies: interactions
  • radio continuum: galaxies


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