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Science with the ngVLA: Extreme Scattering Events and Symmetric Achromatic Variations

Vedantham, H. K. (2018) Science with the ngVLA: Extreme Scattering Events and Symmetric Achromatic Variations. . (Unpublished)

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Radio variability in quasars has been seen on timescales ranging from days to years due to both intrinsic and propagation induced effects. Although separating the two is not always straight-forward, observations of singular `events' in radio light curves have led to two compelling, and thus far unresolved mysteries in propagation induced variability--- extreme scattering events (ESE) that are a result of plasma lensing by AU-scale ionized structures in the interstellar medium, and symmetric achromatic variability (SAV) that is likely caused by gravitational lensing by ≳10^3M⊙ objects. Nearly all theoretical explanations describing these putative lenses have remarkable astrophysical implications. In this chapter we introduce these phenomena, state the unanswered questions and discuss avenues to answer them with a ∼weekly-cadence flux-monitoring survey of 10^3−10^4 flat-spectrum radio quasars with the ngVLA.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Vedantham, H. K.0000-0002-0872-181X
Record Number:CaltechAUTHORS:20190930-133838146
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98961
Deposited By: Tony Diaz
Deposited On:30 Sep 2019 20:44
Last Modified:03 Oct 2019 21:46

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