2024/05/29 by Broadhurst, Tom, Li, Sung Kei, Alfred, Amruth +18 · 1 citation
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2405.19422
Microlensed stars recently discovered by JWST & HST follow closely the winding critical curve of A370 along all sections of the ``Dragon Arc" traversed by the critical curve. These transients are fainter than mAB>26.5, corresponding to the Asymptotic Giant Branch (AGB) and microlensed by diffuse cluster stars observed with ≃ 18M_\odot/pc2, or about ≃ 1% of the projected dark matter density. Most microlensed stars appear along the inner edge of the critical curve, following an asymmetric band of width ≃ 4kpc that is skewed by -0.7±0.2kpc. Some skewness is expected as the most magnified images should form along the inner edge of the critical curve with negative parity, but the predicted shift is small ≃ -0.04kpc and the band of predicted detections is narrow, ≃ 1.4kpc. Adding CDM-like dark halos of 106-8M_\odot broadens the band as desired but favours detections along the outer edge of the critical curve, in the wrong direction, where sub-halos generate local Einstein rings. Instead, the interference inherent to ``Wave Dark Matter" as a Bose-Einstein condensate (ψDM) forms a symmetric band of critical curves that favours negative parity detections. A de Broglie wavelength of ≃ 10pc matches well the observed 4kpc band of microlenses and predicts negative skewness ≃ -0.6kpc, similar to the data. The implied corresponding boson mass is ≃ 10-22eV, in good agreement with estimates from dwarf galaxy cores when scaled by momentum. Further JWST imaging may reveal the pattern of critical curves by simply ``joining the dots" between microlensed stars, allowing wave corrugations of ψDM to be distinguished from CDM sub-halos