New Tests of Milli-lensing in the Blazar PKS 1413 + 135

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • A. L. Peirson
  • I. Liodakis
  • A. C. S Readhead
  • M. L. Lister
  • E. S. Perlman
  • M. F. Aller
  • R. D. Blandford
  • D. A. Green
  • M. A. Gurwell
  • M. W. Hodges
  • T. Hovatta
  • S. Kiehlmann
  • A. Lähteenmäki
  • W. Max-Moerbeck
  • T. Mcaloone
  • S. O’Neill
  • V. Pavlidou
  • T. J. Pearson
  • V. Ravi
  • R. A. Reeves
  • P. F. Scott
  • G. B. Taylor
  • D. J. Titterington
  • M. Tornikoski
  • H. K. Vedantham
  • P. N. Wilkinson
  • J. A. Zensus

Abstract

Symmetric achromatic variability (SAV) is a rare form of radio variability in blazars that has been attributed to gravitational milli-lensing by a ∼102-105 M ⊙ mass condensate. Four SAVs have been identified between 1980 and 2020 in the long-term radio monitoring data of the blazar PKS 1413 + 135. We show that all four can be fitted with the same, unchanging, gravitational lens model. If SAV is due to gravitational milli-lensing, PKS 1413 + 135 provides a unique system for studying active galactic nuclei with unprecedented microarcsecond resolution, as well as for studying the nature of the milli-lens itself. We discuss two possible candidates for the putative milli-lens: a giant molecular cloud hosted in the intervening edge-on spiral galaxy, and an undetected dwarf galaxy with a massive black hole. We find a significant dependence of SAV crossing time on frequency, which could indicate a fast shock moving in a slower underlying flow. We also find tentative evidence for a 989 day periodicity in the SAVs, which, if real, makes possible the prediction of future SAVs: the next three windows for possible SAVs begin in 2022 August, 2025 May, and 2028 February.

Bibliographical metadata

Original languageEnglish
Article number24
JournalThe Astrophysical Journal
Volume927
Issue number1
DOIs
Publication statusPublished - 1 Mar 2022