The unification of powerful quasars and radio galaxies and their relation to other massive galaxies

Abstract

The unification model for powerful radio galaxies and radio-loud quasars postulates that these objects are intrinsically the same but viewed along different angles. Herschel Space Observatory data permit the assessment of that model in the far-infrared spectral window. We analyze photometry from Spitzer and Herschel for the distant 3CR hosts, and find that radio galaxies and quasars have different mid-infrared, but indistinguishable far-infrared colors. Both these properties, the former being orientation dependent and the latter orientation invariant, are in line with expectations from the unification model. Adding powerful radio-quiet active galaxies and typical massive star-forming galaxies to the analysis, we demonstrate that infrared colors not only provide an orientation indicator, but can also distinguish active from star-forming galaxies.

12 pages, 2 figures, 1 table. Accepted for publication in ApJ Letters

References in corpus (7)

• Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the far infrared continuum of QSOs
• Spitzer Reveals Hidden Quasar Nuclei in Some Powerful FR II Radio Galaxies
• Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project
• Star formation in z>1 3CR host galaxies as seen by Herschel
• Spitzer Mid-IR Spectroscopy of Powerful 2Jy and 3CRR Radio Galaxies. II. AGN Power Indicators and Unification
• Near- and mid-infrared photometry of high-redshift 3CR sources
• The dust masses of powerful radio galaxies: clues to the triggering of their activity

Cited by in corpus (4)

• Composite Spectral Energy Distributions and Infrared-Optical Colors of Type 1 and Type 2 Quasars
• A robust derivation of the tight relationship of radio core dominance to inclination angle in high redshift 3CRR sources
• Starbursts and dusty tori in distant 3CR radio galaxies
• Radio properties of high-redshift galaxies at $z\ge 1$