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Symmetric Achromatic Variability in Active Galaxies: A Powerful New Gravitational Lensing Probe?

Vedantham, H. K. and Readhead, A. C. S. and Hovatta, T. and Pearson, T. J. and Blandford, R. D. and Gurwell, M. A. and Lähteenmäki, A. and Max-Moerbeck, W. and Pavlidou, V. and Ravi, V. and Reeves, R. A. and Richards, J. L. and Tornikoski, M. and Zensus, J. A. (2017) Symmetric Achromatic Variability in Active Galaxies: A Powerful New Gravitational Lensing Probe? Astrophysical Journal, 845 (2). Art. No. 89. ISSN 0004-637X. doi:10.3847/1538-4357/aa745c.

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We report the discovery of a rare new form of long-term radio variability in the light curves of active galaxies (AG)—symmetric achromatic variability (SAV)—a pair of opposed and strongly skewed peaks in the radio flux density observed over a broad frequency range. We propose that SAV arises through gravitational milli-lensing when relativistically moving features in AG jets move through gravitational lensing caustics created by 10^3-10^6 M⊙ subhalo condensates or black holes located within intervening galaxies. The lower end of this mass range has been inaccessible with previous gravitational lensing techniques. This new interpretation of some AG variability can easily be tested and if it passes these tests, will enable a new and powerful probe of cosmological matter distribution on these intermediate-mass scales, as well as provide, for the first time, micro-arcsecond resolution of the nuclei of AG—a factor of 30–100 greater resolution than is possible with ground-based millimeter very-long-baseline interferometry.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Vedantham, H. K.0000-0002-0872-181X
Readhead, A. C. S.0000-0001-9152-961X
Hovatta, T.0000-0002-2024-8199
Pearson, T. J.0000-0001-5213-6231
Blandford, R. D.0000-0002-1854-5506
Gurwell, M. A.0000-0003-0685-3621
Max-Moerbeck, W.0000-0002-5491-5244
Ravi, V.0000-0002-7252-5485
Reeves, R. A.0000-0001-5704-271X
Tornikoski, M.0000-0003-1249-6026
Additional Information:© 2017 The American Astronomical Society. Received 2017 February 8; revised 2017 May 2; accepted 2017 May 16; published 2017 August 15. The authors thank Russell Keeney for his tireless efforts in maintaining and operating the OVRO 40 m Telescope. We thank Sterl Phinney and Shrinivas Kulkarni for useful discussions. The OVRO 40 m program has been supported by NASA grants NNG06GG1G, NNX08AW31G, NNX11A043G, and NNX13AQ89G and NSF grants AST-0808050, and AST-1109911. 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. H. Vedantham is an RA and GB Millikan fellow of experimental physics. T. Hovatta was supported in part by the Academy of Finland project number 267324. R. Reeves gratefully acknowledges support from the Chilean Basal Centro de Excelencia en Astrofisica y Tecnologias Afines (CATA) grant PFB-06/2007. Facilities: OVRO:40 m, Keck:I (LRIS), Metsähovi Radio Observatory, SMA.
Group:Astronomy Department
Funding AgencyGrant Number
Smithsonian InstitutionUNSPECIFIED
Academia SinicaUNSPECIFIED
Academy of Finland267324
Subject Keywords:BL Lacertae objects: individual (J1415+1320) ; gravitational lensing: strong; radio continuum: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20170814-131726272
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Official Citation:H. K. Vedantham et al 2017 ApJ 845 89
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80360
Deposited By: George Porter
Deposited On:15 Aug 2017 15:51
Last Modified:15 Nov 2021 19:30

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