Blazar Sheath Illumination of the Outer Molecular Torus: A Resolution of the Seed Photon Problem for the Far-GeV Blazar Flares

Thumbnail Image

Files

1712.07498.pdf (889.92 KB)

Links to Files

https://iopscience.iop.org/article/10.3847/1538-4357/aaa1ee

Permanent Link

10.3847/1538-4357/aaa1ee
 http://hdl.handle.net/11603/19487

Collections

UMBC Physics Department
UMBC Faculty Collection
UMBC Joint Center for Earth Systems Technology (JCET)

Author/Creator

Author/Creator ORCID

Date

2018-01-18

Type of Work

journal articles preprints
Text

Department

Program

Citation of Original Publication

Peter Breiding, Markos Georganopoulos and Eileen T. Meyer, Blazar Sheath Illumination of the Outer Molecular Torus: A Resolution of the Seed Photon Problem for the Far-GeV Blazar Flares, The Astrophysical Journal, Volume 853, Number 1 (2018), 10.3847/1538-4357/aaa1ee

Rights

This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
© 2018. The American Astronomical Society. All rights reserved.

Subjects

Abstract

Recent multiwavelength work led by the Boston University blazar group (e.g., Marscher et al.) strongly suggests that a fraction of the blazar flares seen by the Fermi Large Area Telescope (LAT) take place a few to several pc away from the central engine. However, at such distances from the central engine, there is no adequate external photon field to provide the seed photons required for producing the observed GeV emission under leptonic inverse Compton (IC) models. A possible solution is a spine-sheath geometry for the emitting region (MacDonald et al., but see Nalewajko et al.). Here we use the current view of the molecular torus (e.g., Elitzur; Netzer), in which the torus extends a few pc beyond the dust sublimation radius with dust clouds distributed with a declining density for decreasing polar angle. We show that for a spine-sheath blazar jet embedded in the torus, the wide beaming pattern of the synchrotron radiation of the relatively slow sheath will heat molecular clouds with subsequent IR radiation that will be highly boosted in the spine comoving frame, and that under reasonable conditions this photon field can dominate over the sheath photons directly entering the spine. If the sheath is sufficiently luminous it will sublimate the dust, and if the sheath synchrotron radiation extends to optical-UV energies (as may happen during flares), this will illuminate the sublimated dust clouds to produce emission lines that will vary in unison with the optical-UV continuum, as has been very recently reported for blazar CTA 102 (Jorstad et al.).