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The Relativistic Jet Orientation and Host Galaxy of the Peculiar Blazar PKS 1413+135

Readhead, A. C. S. and Ravi, V. and Liodakis, I. and Lister, M. L. and Singh, V. and Aller, M. F. and Blandford, R. D. and Browne, I. W. A. and Gorjian, V. and Grainge, K. J. B. and Gurwell, M. A. and Hodges, M. W. and Hovatta, T. and Kiehlmann, S. and Lähteenmäki, A. and McAloone, T. and Max-Moerbeck, W. and Pavlidou, V. and Pearson, T. J. and Peirson, A. L. and Perlman, E. S. and Reeves, R. A. and Soifer, B. T. and Taylor, G. B. and Tornikoski, M. and Vedantham, H. K. and Werner, M. and Wilkinson, P. N. and Zensus, J. A. (2021) The Relativistic Jet Orientation and Host Galaxy of the Peculiar Blazar PKS 1413+135. Astrophysical Journal, 907 (2). Art. No. 61. ISSN 1538-4357.

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PKS 1413+135 is one of the most peculiar blazars known. Its strange properties led to the hypothesis almost four decades ago that it is gravitationally lensed by a mass concentration associated with an intervening galaxy. It exhibits symmetric achromatic variability, a rare form of variability that has been attributed to gravitational milli-lensing. It has been classified as a BL Lac object, and is one of the rare objects in this class with a visible counterjet. BL Lac objects have jet axes aligned close to the line of sight. It has also been classified as a compact symmetric object—objects that have jet axes not aligned close to the line of sight. Intensive efforts to understand this blazar have hitherto failed to resolve even the questions of the orientation of the relativistic jet and the host galaxy. Answering these two questions is important because they challenge our understanding of jets in active galactic nuclei and the classification schemes we use to describe them. We show that the jet axis is aligned close to the line of sight and PKS 1413+135 is almost certainly not located in the apparent host galaxy, but is a background object in the redshift range 0.247 < z < 0.5. The intervening spiral galaxy at z = 0.247 provides a natural host for the putative lens responsible for symmetric achromatic variability and is shown to be a Seyfert 2 galaxy. We also show that, as for the radio emission, a "multizone" model is needed to account for the high-energy emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Readhead, A. C. S.0000-0001-9152-961X
Ravi, V.0000-0002-7252-5485
Liodakis, I.0000-0001-9200-4006
Lister, M. L.0000-0003-1315-3412
Singh, V.0000-0002-6040-4993
Aller, M. F.0000-0003-2483-2103
Blandford, R. D.0000-0002-1854-5506
Browne, I. W. A.0000-0002-0743-8430
Gorjian, V.0000-0002-8990-2101
Grainge, K. J. B.0000-0002-6780-1406
Gurwell, M. A.0000-0003-0685-3621
Hovatta, T.0000-0002-2024-8199
Kiehlmann, S.0000-0001-6314-9177
Lähteenmäki, A.0000-0002-0393-0647
McAloone, T.0000-0002-2041-9920
Max-Moerbeck, W.0000-0002-5491-5244
Pavlidou, V.0000-0002-0870-1368
Pearson, T. J.0000-0001-5213-6231
Peirson, A. L.0000-0001-6292-1911
Perlman, E. S.0000-0002-3099-1664
Reeves, R. A.0000-0001-5704-271X
Taylor, G. B.0000-0001-6495-7731
Tornikoski, M.0000-0003-1249-6026
Vedantham, H. K.0000-0002-0872-181X
Zensus, J. A.0000-0001-7470-3321
Additional Information:© 2021 The American Astronomical Society. Received 2020 September 29; revised 2020 November 24; accepted 2020 December 2; published 2021 January 29. We thank the anonymous referee for helpful comments on the original manuscript. We thank Jonathan Sievers and Charles Steidel for useful discussions. The OVRO 40 m program was supported by NASA grants NNG06GG1G, NNX08AW31G, NNX11A043G, and NNX13AQ89G from 2006 to 2016 and NSF grants AST-0808050 and AST-1109911 from 2008 to 2014. T.H. was supported by Academy of Finland projects 317383 and 320085. W.M. acknowledges support from ANID projects Basal AFB-170002 and PAI79160080. R.R. acknowledges support from ANID Basal AFB-170002, and ANID-FONDECYT grant 1181620. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution and the Academia Sinica. This work is based in part on archival data obtained with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by an award issued by JPL/Caltech. The Combined Atlas of Sources with Spitzer IRS Spectra (CASSIS) is a product of the IRS instrument team, supported by NASA and JPL. CASSIS is supported by the "Programme National de Physique Stellaire" (PNPS) of CNRS/INSU co-funded by CEA and CNES and through the "Programme National Physique et Chimie du Milieu Interstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES. This paper is dedicated to the memory of Neil Gehrels, who facilitated support that enabled us to bring the 40 m Telescope out of mothballs and commission it for the 15 GHz monitoring program in support of Fermi-LAT, without which this work could not have been done. Facilities: Fermi (LAT) - , Keck:I (LRIS) - , Metsähovi Radio Observatory - , OVRO:40m - , SMA, Spitzer - , UMRAO - , VLBA. -
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Academy of Finland317383
Academy of Finland320085
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1181620
Programme National de Physique Stellaire (PNPS)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Programme National Physique et Chimie du Milieu Interstellaire (PCMI)UNSPECIFIED
Institut de chimie du CNRSUNSPECIFIED
Institut National du Patrimoine (INP)UNSPECIFIED
Smithsonian InstitutionUNSPECIFIED
Academia SinicaUNSPECIFIED
Subject Keywords:Radio active galactic nuclei ; Strong gravitational lensing ; Blazars ; Relativistic jets ; Seyfert galaxies ; Apparent superluminal motion
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Radio active galactic nuclei (2134); Strong gravitational lensing (1643); Blazars (164); Relativistic jets (1390); Seyfert galaxies (1447); Apparent superluminal motion (61)
Record Number:CaltechAUTHORS:20210106-131338618
Persistent URL:
Official Citation:A. C. S. Readhead et al 2021 ApJ 907 61
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107353
Deposited By: George Porter
Deposited On:12 Jan 2021 15:47
Last Modified:29 Jan 2021 18:44

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