Beyond collective fluctuations: probing micro-image swarms in lensed quasars with intensity interferometry

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Hauptverfasser: Meena, Ashish Kumar, Saha, Prasenjit
Format: Preprint
Veröffentlicht: 2026
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author Meena, Ashish Kumar
Saha, Prasenjit
author_facet Meena, Ashish Kumar
Saha, Prasenjit
contents Each strongly lensed image of a quasar behind a lensing galaxy (or galaxy cluster) is composed of a swarm of micro-images. This is a result of microlensing due to stellar-scale substructure in the lens. The presence of microlenses forms a network of micro-caustics, and a source transiting these micro-caustics gives rise to variation in observed strongly lensed images. These micro-image swarms are currently observable only through collective intensity fluctuations, which hide the underlying information on the stellar (and compact dark matter, if any) mass functions within the swarm. To unlock the information present in micro-image swarms, it is necessary to explore new techniques. In this work, we study the prospects of determining the micro-image swarm size in lensed quasar images using the intensity interferometry (i.e., the Hanbury Brown & Twiss effect). We consider QSO 2237+0305 and PS J0147+4630, two of the brightest lens quasars in the sky, and study micro-image swarm features in visibility space for both macro-minimum and macro-saddle-point images. At the end, we argue that, with ongoing and expected technical advances, observations of micro-image swarms are plausible, at least for the brightest lensed quasars.
format Preprint
id arxiv_https___arxiv_org_abs_2605_02181
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Beyond collective fluctuations: probing micro-image swarms in lensed quasars with intensity interferometry
Meena, Ashish Kumar
Saha, Prasenjit
Cosmology and Nongalactic Astrophysics
Each strongly lensed image of a quasar behind a lensing galaxy (or galaxy cluster) is composed of a swarm of micro-images. This is a result of microlensing due to stellar-scale substructure in the lens. The presence of microlenses forms a network of micro-caustics, and a source transiting these micro-caustics gives rise to variation in observed strongly lensed images. These micro-image swarms are currently observable only through collective intensity fluctuations, which hide the underlying information on the stellar (and compact dark matter, if any) mass functions within the swarm. To unlock the information present in micro-image swarms, it is necessary to explore new techniques. In this work, we study the prospects of determining the micro-image swarm size in lensed quasar images using the intensity interferometry (i.e., the Hanbury Brown & Twiss effect). We consider QSO 2237+0305 and PS J0147+4630, two of the brightest lens quasars in the sky, and study micro-image swarm features in visibility space for both macro-minimum and macro-saddle-point images. At the end, we argue that, with ongoing and expected technical advances, observations of micro-image swarms are plausible, at least for the brightest lensed quasars.
title Beyond collective fluctuations: probing micro-image swarms in lensed quasars with intensity interferometry
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2605.02181