ITAL]Chandra[/ITAL] Observations of the Gravitationally Lensed System 2016+112

Abstract

An observation of the gravitationally lensed system 2016+112 with the Chandra X-Ray Observatory has resolved a mystery regarding the proposed presence of a dark matter object in the lens plane of this system. The Chandra Advanced CCD Imaging Spectrometer observation has clearly detected the lensed images of 2016+112 with positions in good agreement with those reported in the optical and also detects 13 additional X-ray sources within a radius of 35. Previous X-ray observations in the direction of 2016+112 with the ROSAT HRI and ASCA Solid-State Imaging Spectrometer have interpreted the X-ray data as arising from extended emission from a dark cluster. However, the present Chandra observation can account for all the X-ray emission as originating from the lensed images and additional point X-ray sources in the field. Thus, cluster parameters based on previous X-ray observations are unreliable. We place a 3 σ upper limit on the 2-10 keV flux and luminosity of the cluster of 1.6 × 10-14 ergs s-1 cm-2 and 1.7 × 1044 ergs s-1, respectively. We estimate an upper limit on the mass-to-light ratio within a radius of 800 h kpc of M/LV < 190 h50 (M/LV)☉. None of the additional point X-ray sources are associated with the galaxy cluster members recently detected in deep optical and IR observations.