All good things come in threes: the third image of the lensed quasar PKS1830-211

Abstract

Strong gravitational lensing distorts our view of sources at cosmological distances but brings invaluable constraints on the mass content of foreground objects and on the geometry and properties of the Universe. We report the detection of a third continuum source toward the strongly lensed quasar PKS1830-211 in ALMA multi-frequency observations of high dynamic range and high angular resolution. This third source is point-like and located slightly to the north of the diagonal joining the two main lensed images, A and B, 0.3 arcsec away from image B. It has a flux density that is ~140 times weaker than images A and B and a similar spectral index, compatible with synchrotron emission. We conclude that this source is most likely the expected highly de-magnified third lensed image of the quasar. In addition, we detect, for the first time at millimeter wavelengths, weak and asymmetrical extensions departing from images A and B that correspond to the brightest regions of the Einstein ring seen at centimeter wavelengths. Their spectral index is steeper than that of compact images A, B, and C, which suggests that they arise from a different component of the quasar. Using the GravLens code, we explore the implications of our findings on the lensing model and propose a simple model that accurately reproduces our ALMA data and previous VLA observations. With a more precise and accurate measurement of the time delay between images A and B, the system PKS1830-211 could help to constrain the Hubble constant to a precision of a few percent.

accepted for publication in A&A Letter

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Cited by in corpus (15)

• Strong Lensing by Galaxies
• A study of submillimeter methanol absorption toward PKS1830-211: Excitation, invariance of the proton-electron mass ratio, and systematics
• SMILE: Search for MIlli-LEnses
• PKS1830-211: OH and HI at z=0.89 and the first MeerKAT UHF spectrum
• Cosmo-tomography toward PKS1830-211: Variability of the quasar and of its foreground molecular absorption monitored with ALMA
• Gravitational lensing effects of supermassive black holes in cluster environments
• Study of Temporal and Spectral variability for Blazar PKS 1830-211 with Multi-Wavelength Data
• Discovery of Hydrogen Radio Recombination Lines at z=0.89 towards PKS 1830-211
• Constraints on the Inner Regions of Lensing Galaxies from Central Images using a Recent AGN Offset Distribution
• On the scarcity of redshifted OH and millimetre-band molecular absorption
• Carbonates and ices in the $z=0.89$ galaxy-absorber towards PKS 1830-211 and within star-forming regions of the Milky Way
• A sub-ppm upper limit on the cosmological variations of the fine structure constant alpha
• Time delay measurements with Broken Power Law model
• An improved time delay from VLA and ATCA monitoring of the gravitational lens system PKS 1830-211
• Constraining $\gamma$-ray dissipation site in gravitationally lensed quasar -- PKS 1830$-$211