Published in

American Astronomical Society, Astronomical Journal, 6(158), p. 237, 2019

DOI: 10.3847/1538-3881/ab5108

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Image Flux Ratios of Gravitationally Lensed HS 0810+2554 with High-resolution Infrared Imaging

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Data provided by SHERPA/RoMEO

Abstract

Abstract We report near simultaneous imaging using LMIRCam on the LBTI of the quadruply imaged lensed quasar HS 0810+2554 at wavelengths of 2.16, 3.7, and 4.78 μm with a full width at half maximum spatial resolution of 0.″13, 0.″12, and 0.″15 respectively, comparable to Hubble Space Telescope optical imaging. In the z = 1.5 rest frame of the quasar, the observed wavelengths correspond to 0.86, 1.48, and 1.91 μm respectively. The two brightest images in the quad, A and B, are clearly resolved from each other with a separation of 0.″187. The flux ratio of these two images (A/B) trends from 1.79 to 1.23 at wavelengths from 2.16 to 4.78 μm. The trend in flux ratio is consistent with the 2.16 μm flux originating from a small sized accretion disk in the quasar that experiences only microlensing. The excess flux above the contribution from the accretion disk at the two longer wavelengths originates from a larger sized region that experiences no microlensing. A simple model employing multiplicative factors for image B due to stellar microlensing (m) and substructure millilensing (M) is presented. The result is tightly constrained to the product m × M = 1.79. Given the observational errors, the 60% probability contour for this product stretches from m = 2.6, M = 0.69 to m = 1.79, M = 1.0, where the later is consistent with microlensing only.