We present new radio observations of the large-separation gravitationally lensed quasar SDSS J1004+4112, taken in a total of 6 hr of observations with the Expanded Very Large Array. The maps reach a thermal noise level of approximately 4 μJy. We detect four of the five lensed images at the 15-35 μJy level, representing a source of intrinsic flux density, after allowing for lensing magnification, of about 1 μJy, intrinsically probably the faintest radio source yet detected. This reinforces the utility of gravitational lensing in potentially allowing us to study nJy-level sources before the advent of the Square Kilometre Array. In an optical observation taken three months after the radio observation, image C is the brightest image, whereas the radio map shows flux density ratios consistent with previous optical observations. Future observations separated by a time delay will give the intrinsic flux ratios of the images in this source. © 2011. The American Astronomical Society. All rights reserved.
|Journal||Astrophysical Journal Letters|
|Publication status||Published - 20 Sep 2011|
- gravitational lensing: strong
- quasars: individual (SDSS J1004+4112)
- radio continuum: galaxies