The Peculiar Light Curve of J1415+1320: A Case Study in Extreme Scattering Events

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • California Institute of Technology
  • University of Turku
  • University of Groningen
  • Stanford University
  • Harvard University
  • Max Planck Institute for Radio Astronomy
  • University of Crete
  • Universidad de Concepcion

Abstract

The radio light curve of J1415+1320 (PKS 1413+135) shows time-symmetric and recurring U-shaped features across the centimeter-wave and millimeter-wave bands. The symmetry of these features points to lensing by an intervening object as the cause. U-shaped events in radio light curves in the centimeter-wave band have previously been attributed to Extreme scattering events (ESE). ESEs are thought to be the result of lensing by compact plasma structures in the Galactic interstellar medium, but the precise nature of these plasma structures remains unknown. Since the strength of a plasma lens evolves with wavelength λ as , the presence of correlated variations at over a wide wavelength range casts doubt on the canonical ESE interpretation for J1415+1320. In this paper, we critically examine the evidence for plasma lensing in J1415+1320. We compute limits on the lensing strength and the associated free-free opacity of the putative plasma lenses. We compare the observed and model ESE light curves, and also derive a lower limit on the lens distance based on the effects of parallax due to the Earth's orbit around the Sun. We conclude that plasma lensing is not a viable interpretation for J1415+1320's light curves and that symmetric U-shaped features in the radio light curves of extragalactic sources do not present prima facie evidence for ESEs. The methodology presented here is generic enough to be applicable to any plasma-lensing candidate.

Details

Original languageEnglish
Article number90
Number of pages9
JournalAstrophysical Journal
Volume845
Issue number2
Publication statusPublished - 20 Aug 2017
MoE publication typeA1 Journal article-refereed

    Research areas

  • BL Lacertae objects: individual (PKS 1413+135), galaxies: jets, ISM: structure, scattering

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