Detection of a Companion Lens Galaxy Using the Mid-Infrared Flux Ratios of the Gravitationally Lensed Quasar H1413+117
Abstract
We present the first resolved mid-infrared (IR) (11 μm) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a "flux anomaly," where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to reproduce the mid-IR flux ratios, which are insensitive to extinction and microlensing, by modeling the main lens as a singular isothermal ellipsoid. This model fails to reproduce the flux ratios. However, we can explain the flux ratios simply by adding to the model a nearby galaxy detected in the H band by the Hubble Space Telescope. This perturbing galaxy lies 4farcs0 from the main lens and it has a critical radius of 0farcs63 ± 0farcs02 which is similar to that of the main lens, as expected from their similar H-band fluxes. More remarkably, this galaxy is not required to obtain a good fit to the system astrometry, so this represents the first clear detection of an object through its effect on the image fluxes of a gravitational lens. This is a parallel to the detections of visible satellites from astrometric anomalies, and provides a proof of the concept of searching for substructure in galaxies using anomalous flux ratios.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2009
- DOI:
- 10.1088/0004-637X/699/2/1578
- arXiv:
- arXiv:0904.0275
- Bibcode:
- 2009ApJ...699.1578M
- Keywords:
-
- galaxies: structure;
- gravitational lensing;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 11 pages, 4 figures, 4 tables, Submitted to ApJ. v4: Figure 1 corrected