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| Paper: |
Supermagnified Stars in Lensing Clusters and Small-Scale Structure in the Dark Matter |
| Monograph: |
11, HWO25 Proceedings Part II: Mission Framework, Technology, and Broader Contributions |
| Page: |
73 |
| Authors: |
Gabriel Torralba and Jordi Miralda-Escudé |
| DOI: |
10.26624/IMWI2770 |
| Abstract: |
Supermagnified stars, discovered by HST and JWST in lensing clusters
of galaxies, are luminous stars in source galaxies lying near lensing caustics
that are magnified by large factors (z∼ 1000z), making them detectable at
cosmological distances. Intracluster stars in the lens modify the large-scale
caustic into a corrugated network of micro-caustics, causing frequent
microlensing events of the supermagnified stars. The frequency and lightcurves
of these micro-caustic crossings are extremely sensitive to any small-scale,
low amplitude surface density fluctations in the lensing cluster, making them
a unique probe to dark matter minihalos or any small-scale irregularities.
Furthermore, the disks of supermagnified stars can be resolved
(at cosmological distances!) from photometric monitoring of micro-caustic
crossing events, exploiting the limb darkening effect. Examples are shown of
model lightcurves to fit the Kelly et al.\ (2018) observations of the first
supermagnified star discovered. The unique sensitivity and angular resolution
of the Habitable Worlds Observatory enables photometry of microlensing events
of supermagnified stars sensitive to small-scale structure different from
intracluster stars, a probe to the nature of dark matter that is not
accessible to other observations at present. |
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