2 code implementations • 14 Aug 2020 • Simon Birrer, Tommaso Treu
Time-delay cosmography can reach sufficient precision to resolve the Hubble tension at 3-5$\sigma$, without assumptions on the radial mass profile of lens galaxies.
Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies
2 code implementations • 21 Jan 2020 • Lilan Yang, Simon Birrer, Tommaso Treu
For multiply-imaged sources, the tool can also fit and apply first (deflection) second (shear, convergence) and third order (flexion) corrections to the local gravitational potential to improve the overall reconstruction, depending on the quality of the data.
Astrophysics of Galaxies Instrumentation and Methods for Astrophysics
1 code implementation • 17 Sep 2019 • Nikki Arendse, Radosław J. Wojtak, Adriano Agnello, Geoff C. -F. Chen, Christopher D. Fassnacht, Dominique Sluse, Stefan Hilbert, Martin Millon, Vivien Bonvin, Kenneth C. Wong, Frédéric Courbin, Sherry H. Suyu, Simon Birrer, Tommaso Treu, Leon V. E. Koopmans
Results from time-delay lenses are consistent with those from distance-ladder calibrations and point to a discrepancy between absolute distance scales measured from the CMB (assuming the standard cosmological model) and late-time observations.
Cosmology and Nongalactic Astrophysics
1 code implementation • 24 Apr 2019 • Simon Birrer, Tommaso Treu
The time delay between the arrival of photons of multiple images of time variable sources can be used to constrain absolute distances in the Universe (Refsdal 1964), and in turn obtain a direct estimate of the Hubble constant and other cosmological parameters.
Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies
1 code implementation • 4 Jan 2018 • Xuheng Ding, Tommaso Treu, Anowar J. Shajib, Dandan Xu, Geoff C. -F. Chen, Anupreeta More, Giulia Despali, Matteo Frigo, Christopher D. Fassnacht, Daniel Gilman, Stefan Hilbert, Philip J. Marshall, Dominique Sluse, Simona Vegetti
The goal of the challenge is to infer $H_0$ for each rung, given the HST images, the time delay, and a stellar velocity dispersion of the deflector, for a fixed background cosmology.
Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies
