期刊
ASTROPHYSICAL JOURNAL
卷 699, 期 2, 页码 1720-1731出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/699/2/1720
关键词
dark matter; gravitational lensing; time
资金
- Space Telescope Science Institute [HST-AR-10668]
- NASA [NAS5-26555]
- NSF [AST-0747311]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0747311] Funding Source: National Science Foundation
We show that dark matter substructure in galaxy-scale halos perturbs the time delays between images in strong gravitational lens systems. The variance of the effect depends on the subhalo mass function, scaling as the product of the substructure mass fraction, and a characteristic mass of subhalos (namely < m(2)>/< m >). Time delay perturbations therefore complement gravitational lens flux ratio anomalies and astrometric perturbations by measuring a different moment of the subhalo mass function. Unlike flux ratio anomalies, time delay millilensing is unaffected by dust extinction or stellar microlensing in the lens galaxy. Furthermore, we show that time delay ratios are immune to the radial profile degeneracy that usually plagues lens modeling. We lay out a mathematical theory of time delay perturbations and find it to be tractable and attractive. We predict that in cusp lenses with close triplets of images, substructure may change the arrival-time order of the images (compared with smooth models). We discuss the possibility that this effect has already been observed in RX J1131-1231.
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