Michele Cappellari

Abstract:

We present a blind time-delay cosmography measurement of the Hubble-Lemaître constant H0 based on the quadruply imaged quasar SDSSJ1433 + 6007. Our analysis combines deep Hubble Space Telescope imaging, extended time-delay monitoring from the Wendelstein and Maidanak Observatories, and spatially resolved stellar kinematics from the Keck Cosmic Web Imager and Reionization Mapper. We build a robust lens model to reconstruct the mass distribution and high-signal-to-noise kinematic maps to break the mass-sheet degeneracy, explicitly accounting for the lens galaxy’s oblateness, rotation, and anisotropy. Furthermore, we constrain the external convergence (κext) by characterizing the line-of-sight environment using wide-field photometry from the Dark Energy Spectroscopic Instrument (DESI) Legacy Survey data release 10. We incorporate these constraints into our joint lensing and dynamical model, running multiple iterations to estimate random and systematic uncertainties. Accounting for maximal flexibility of the mass-sheet transformation, and assuming a flat Λ cold dark matter cosmology and an Ωm,0 prior from DESI data release 2, we infer H0=73.2-4.7+4.8 km s-1 Mpc-1 (a 6.5% precision) and an internal mass-sheet parameter λint=1.12-0.06+0.05. Notably, λint is 2σ away from unity for this system, highlighting the importance of treating it as a free parameter. Our H0 measurement is consistent with the result from our 2025 milestone paper, and it will be included in our next hierarchical analysis to improve the overall precision. Moving forward, the comprehensive pipeline demonstrated herein establishes a robust framework that can be readily applied to future strongly lensed systems to further refine cosmological constraints.

Abstract:

Dynamical modelling can be used to constrain the masses of central black holes, but it is challenging to model massive galaxies because of their complex kinematics. We report six new measurements of supermassive black hole masses of massive early-type galaxies from stellar kinematics, which were extracted from adaptive-optics-assisted SINFONI and MUSE observations. We combined the stellar kinematics with HST photometry to build triaxial Schwarzschild orbit-superposition models. Our Schwarzschild models can recover the complex triaxial features of the galaxies and constrain the black hole masses of all six galaxies. We found that strong triaxial kinematic features can bias the mass measurements and corrected for this effect. The derived black hole masses are $(1.14^ DYNAMITE +0.41 _ -0.63 ) _ 10^9$ M_⊙ for NGC 3706, $(1.19^ +1.34 -0.80 ) _ 10^9$ M_⊙ for NGC 3923, $(1.14^ +1.08 -0.95 ) _ 10^9$ M_⊙ for NGC 4261, $(4.68^ +2.99 -4.26 ) _ 10^8$ M_⊙ for NGC 4636, $(3.51^ +3.37 -2.57 ) _ 10^9$ M_⊙ for IC 4296, and $(2.43^ +1.53 -1.65 ) 10^9$ M_⊙ for IC 4329 at a confidence level of 3σ. We compared our measurements with published results from axisymmetric Schwarzschild modelling and with our JAM Jeans Anisotropic models and obtained mostly consistent black hole masses. Most of our black hole mass estimates can be well constrained using MUSE observations alone. All of our mass measurements agree with local black hole scaling relations.