Polarization Insights for Active Galactic Nuclei

Abstract

Optical spectropolarimetry and broadband polarimetry in other wavebands has been a key to understanding many diverse aspects of AGN. In some cases polarization is due to synchrotron radiation, and in other cases it's due to scattering. Recognition of relativistically beamed optical synchrotron emission by polarization was vital for understanding blazars (BL Lacs and Optically Violently Variable quasars), both physically and geometrically. Radio polarimetry of quiescent AGN is equally important, again for both purposes. Scattering polarization was central to the Unified Model for Seyferts, Radio Galaxies and (high ionization) Ultraluminous Infrared Galaxies. It provides a periscope for viewing AGN from other directions. Finally, if we could understand its message, polarization would also provide major insights regarding the nature of the AGN "Featureless Continuum" and Broad (emission) Line Region. I point out that high ionization ULIRGs have all the exact right properties to be called Quasar 2s. Mid-IR observations generally don't penetrate to the nucleus, greatly reducing their ability to diagnose the energy source. In particular, LINER ULIRGs aren't necessarily starburst-dominated, as has been claimed.

29 pages, 10 figures, Tenerife lectures

References in corpus (19)

• What Powers Ultra-luminous IRAS Galaxies?
• A Composite HST Spectrum of Quasars
• Long-term optical variability properties of the Palomar-Green quasars
• The `quiescent' black hole in M87
• Triggered Star Formation in a Massive Galaxy at z=3.8: 4C41.17
• The UV Properties of the Narrow Line Quasar I Zwicky 1
• The Origin of the X-ray and Ultraviolet Emission in NGC 7469
• High Resolution Optical/Near-Infrared Imaging of Cool Ultraluminous Infrared Galaxies
• AN IMPROVED MEASURE OF QUASAR ORIENTATION
• New constraints on the continuum-emission mechanism of AGN: Intensive monitoring of NGC 7469 in the X-ray and ultraviolet
• Unveiling the Active Nucleus of Centaurus A
• The Continuum Slopes of Optically Selected QSOs
• The Vertical Structure and Ultraviolet Spectrum of X-Ray Irradiated Accretion Disks in Active Galactic Nuclei
• HST infrared imaging polarimetry of Centaurus A: implications for the unified scheme and the existence of a mis-directed BL Lac nucleus
• The HST view of FR I radio galaxies: evidence for non-thermal nuclear sources
• X-ray Properties of B2 1028+313: A Quasar at the Center of the Abell Cluster A1030
• The HST view of the FR I / FR II dichotomy
• BeppoSAX unveils the nuclear component in NGC 6240
• The broad line region of narrow-line Seyfert 1 galaxies

Cited by in corpus (14)

• A Hubble Space Telescope Survey of Extended [OIII]5007A Emission in a Far-Infrared Selected Sample of Seyfert Galaxies: Results
• Seyferts on the edge: polar scattering and orientation-dependent polarization in Seyfert 1 nuclei
• Equatorial scattering and the structure of the broad-line region in Seyfert nuclei: evidence for a rotating disc
• Compact steep-spectrum sources as the parent population of flat-spectrum radio-loud NLS1s
• Modeling optical and UV polarization of AGNs V. Dilution by interstellar polarization and the host galaxy
• Binary black holes and tori in AGN II. Can stellar winds constitute a dusty torus?
• 3.1 $\mu$m H${}_2$O Ice Absorption in LINER-Type Ultraluminous Infrared Galaxies with Cool Far-Infrared Colors: the Centrally-Concentrated Nature of Their Deeply Buried Energy Sources
• $NuSTAR$ Observations of Four Nearby X-ray Faint AGN: Low Luminosity or Heavy Obscuration?
• A panchromatic review of thermal and nonthermal active galactic nuclei
• Interstellar Polarization and the Position Angle Orientations of Seyfert 1 Galaxies
• Tracking the state transitions in changing-look active galactic nuclei through their polarized-light echoes
• Polarisation of high energy gamma-rays after scattering
• Double-Peaked Narrow Emission Lines in AGN: The Role of Rotating Disks
• Modelling the polarization dichotomy of Active Galactic Nuclei