arXiv subjects

Felipe Urcelay

Publications and source records attributed to Felipe Urcelay.

7 recordsLinked to original sources

arXiv2026

TDCOSMO 2026: A 3% measurement of the Hubble constant from strong lensing and stellar kinematics

We present cosmological constraints from 11 strongly lensed quasars with measured time delays (hereafter, the TDCOSMO-2026 sample). In addition to expanding the sample, we improve many aspects of our blind analysis with respect to our 2025 analysis. Among other improvements, spatially resolved kinematics are available for nine systems, including six with JWST-NIRSpec, compared to one in 2025; for three lens models, JWST-NIRCam images now replace HST; axisymmetric dynamical modeling is applied directly to the spatially resolved data, instead of an axisymmetric correction factor applied to spherical models; and the line-of-sight convergence is now based on the Euclid Flagship simulations instead of the Millennium Simulation. Our baseline and primary result is based on the TDCOSMO-2026 sample, in combination with a prior on $Ω_{\rm m}$ from the DES-Dovekie supernova sample. In the flat $Λ$ cold dark matter ($Λ$CDM) cosmology, we find $H_0=71.1^{+2.4}_{-2.3}$ km.s$^{-1}$.Mpc$^{-1}$, a 3.3% uncertainty that accounts for the mass-sheet degeneracy. The SLACS and SL2S samples are in excellent agreement with the TDCOSMO-2026 sample, improving the precision on $H_0$ in flat $Λ$CDM to 3.0%. Using the DESI-DR2 baryon acoustic oscillations (BAO) likelihood instead of DES-Dovekie yields fully consistent results. We also present constraints in the open $Λ$CDM, $w$CDM, $w_0w_a$CDM, and $w_ϕ$CDM cosmologies; the TDCOSMO $H_0$ inference is robust and consistent across all of them. The combination of the TDCOSMO+SLACS+SL2S likelihood with those from DESI-DR2 and DES-Dovekie disfavors $w=-1$ at the $2.3$-$2.5σ$ level in all three dark energy extensions that we tested. We find, e.g., $w_0=-0.88^{+0.04}_{-0.05}$ in $w_ϕ$CDM and $w_0 = -0.85^{+0.07}_{-0.06}$ in $w_0w_a$CDM, while $w_a = -0.48^{+0.46}_{-0.44}$ remains consistent with zero.

astro-ph.CO↗

arXiv2026

TDCOSMO 2026: new insights on the Hubble tension from strong lensing time delays

We discuss the measurement of the Hubble constant ($H_0$) in flat $Λ$ cold dark matter cosmology based on the blind hierarchical analysis of 11 multiply-imaged quasars (hereafter the TDCOSMO-2026 sample) and described in greater detail in a companion paper. In addition to the time delays, we use lens models based on high-resolution imaging from the Hubble Space Telescope (HST) and from the James Webb Space Telescope (JWST), analyzed jointly with axisymmetric dynamical models based on JWST-NIRSpec, VLT-MUSE, and Keck-KCWI spectroscopy. Our primary result $H_0=71.1^{+2.4}_{-2.3}$ km.s$^{-1}$.Mpc$^{-1}$ is based on the TDCOSMO-2026 sample, in combination with $Ω_{\rm m}$ constraints from the DES-Dovekie supernova (SN) dataset. Our 3% precision accounts for the mass-sheet degeneracy. Importantly, our measurement is independent of the local distance ladder (LDL). Among individual late-universe probes, only the traditional LDL is more precise. We discuss our result in the context of the Hubble tension, the difference between $H_0$ measured in the late universe and the prediction based on early-universe probes such as the cosmic microwave background (CMB). We construct combinations of independent late-universe probes and show that the tension with the Planck CMB prediction is robust to excluding any one of the methods based on Type-Ia Supernovae, Cepheids, or the Tip of the Red Giant Branch. For example, we construct a 'no-SN' $H_0$ measurement, by replacing the DES-Dovekie constraint on $Ω_{\rm m}$ with that from DESI baryon acoustic oscillations, and then combining TDCOSMO-2026 with independent non-SN late-universe probes. This 'no-SN' late-universe probe is in 3.7$σ$ tension with Planck. Even after completely excluding the LDL, the tension with Planck persists at the 2.7$σ$ level.

astro-ph.CO↗

arXiv2026

The Carousel Lens III: Joint lens convergence and source kinematic modeling

We introduce a new, independent modeling component to the Carousel Lens series by exploiting the spatially-resolved kinematics contained within the lensed arcs, which so far has remained rather underexplored in strong-lensing analyses. We present an end-to-end forward-modeling framework that reconstructs an integral-field spectroscopic datacube from a parameterization of the lens convergence profile together with the line-of-sight velocity, velocity dispersion, and surface brightness profiles of the unlensed source. The kinematic structure of the source acts as an additional set of ray-traceable markers distributed across every lensed image, inaccessible from imaging data alone. Furthermore, by generating an [OII] emission-line datacube, we isolate a single source redshift and remove lens and line-of-sight light contamination. We apply this framework to deep VLT/MUSE observations of the Carousel Lens, modeling the [OII] emission of the quadruply-imaged star-forming galaxy at $z_{\rm s} = 1.432$ that anchors the system's cosmography constraints. We measure an Einstein radius $θ_{\rm E} = 12.816''^{+0.005}_{-0.007}$ and a logarithmic slope $γ= 1.412^{+0.002}_{-0.002}$, tightening the statistical uncertainties on both by roughly a factor of $2-2.5$ relative to the corresponding flat emission-line map model. We find that the source galaxy exhibits a strong rotation, lies confidently along the star-forming main sequence, and has an inferred central black hole mass of $\log M_{\rm BH}/M_{\odot} = 7.89 \pm 0.51$. These results establish datacube-level forward modeling as a practical and independent route to traditional image-based lens models in the current systematics-limited regime, and one that extends naturally to this system's other lensed sources and to other lens systems.

astro-ph.GA↗

arXiv2026

The Carousel Lens I: A Spectroscopic Survey of the Carousel Lens Field

We present a spectroscopic survey of field galaxies and lensed sources in the vicinity of the strong lensing galaxy cluster known as the Carousel lens at z=0.49. Using both Gemini/GMOS slitmask spectra and deep VLT/MUSE observations, we bring the total number of lensed sources up to 12, including three which were not previously known from imaging observations but are apparent in the MUSE data as emission-line sources. Of these sources, 10 have confident redshifts, and an additional 2 have tentative redshifts from likely Ly$α$ emission (including seven new redshifts determined here adding to those presented previously in \cite{Sheu.Cikota.ea2024}). In total, we identify 42 images of these 12 sources. This lens system is remarkably symmetric and well-modeled by a simpler lens model than typical cluster lenses, and the large number of sources and their large range of redshifts make this cluster ideal for constraining cosmological parameters such as $w$ and $Ω_m$ as well as the cluster density profile. Additionally, we present a catalog of 57 unlensed field galaxies with confident redshifts, of which 49 are associated with the cluster. We measure a cluster velocity dispersion of about 1100 km s$^{-1}$ from which we estimate a halo mass $M_{200c} \sim 1.2 \times 10^{15} M_\odot$.

astro-ph.GA↗

arXiv2026

XShooter DESI Lens Program: Sample characterization

Large imaging surveys in cosmology are detecting orders of magnitude more lens systems than known so far. This unprecedented dataset will lead to robust constraints on cosmology and galaxy evolution models. However, a preliminary careful characterization of the lens and source samples are mandatory. In this work, we report on a VLT/XShooter observation program of 67 lens systems to characterize their spectroscopic redshift distribution. These systems were previously detected on the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys by Huang et al. 2021 and Storfer et al. 2022 with deep residual neural network. We manage to measure redshifts for 58 lenses and 57 sources. We also identify 2 sources with indication of outflow in the shape of the emission lines and 7 sources with rotating disks in $[OII]$ or $Hα$. We find no particular bias associated to the redshift measurement operation, meaning that our measured source redshift distribution is likely representative of the true one and can be used to calibrate analyses in large imaging surveys.

astro-ph.CO↗

arXiv2026

SLSim: a strong lensing population simulation package

Gravitational lensing offers unique insights into cosmology by bending light around massive objects. Strong gravitational lensing, in particular, produces magnified and often multiple images of distant sources, crucial for precise cosmological measurements and understanding the distribution of dark matter in the universe. Current studies are limited by the number of strong gravitational lenses. From upcoming cosmological surveys, we anticipate observing a several orders of magnitude increase in the number of lenses, for both static and transient phenomena. However, detecting and analyzing these events from vast surveys like Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) presents significant challenges. To prepare for these challenges, we introduce SLSim, a versatile simulation tool tailored for the Vera C. Rubin Observatory. SLSim integrates advanced astrophysical models with computational efficiency to generate synthetic strong lens populations under realistic observational conditions. SLSim simulates static and variable lensing scenarios, essential for cosmological studies, training and testing lens search and data analysis pipelines. This paper details SLSim,'s design and implementation, emphasizing its modularity and capabilities across various astrophysical regimes. Validation against observational data and existing simulations confirms SLSim's accuracy in reproducing observed lensing phenomena. SLSim is publicly available at https://github.com/LSST-strong-lensing/slsim, and we anticipate continued development and expansion of its capabilities. Users are encouraged to check the repository for updates and to contribute to ongoing community efforts in strong lensing simulations.

astro-ph.CO↗

arXiv2026

The Carousel Lens II: Cosmological Constraints with GIGA-Lens

The nature of dark matter and dark energy are among the central questions in cosmology. Strong gravitational lenses with multiple source planes provide a geometric probe of cosmology: the ratio of deflection angles at different redshifts depends only on angular-diameter distances, constraining the matter density $Ω_m$ and the dark energy equation of state $w$. However, constraints from this technique have historically lagged behind those from the CMB, SNe Ia, and BAO. In this work, we present new cosmological constraints from the Carousel Lens, a cluster-scale lens with more than 40 extended images from 11 spectroscopically confirmed sources. Its relaxed core and rich set of extended images behind the main halo make it particularly suitable for cosmological inference. Using the GIGA-Lens pipeline, we construct a pixel-level lens model including six HST-detected sources and four mass components. From this model, we obtain $w$CDM constraints of $Ω_m = 0.34^{+0.16}_{-0.13}$ and $w = -1.31^{+0.35}_{-0.32}$ from the Carousel Lens alone, accounting for both statistical and systematic uncertainties. We further project that including four additional known higher-redshift sources, assuming similar fractional uncertainties, could improve the constraining power by ~80%, bringing the precision close to that of the CMB and SNe Ia. For an evolving dark energy model ($w_0w_a$CDM), the Carousel Lens alone yields constraints comparable to the CMB, providing an independent and complementary probe alongside SN Ia and BAO. While currently systematic uncertainties dominate, which we quantify through simulations, our results demonstrate that relaxed multi-source-plane cluster lenses can deliver competitive cosmological constraints. Further improvements are expected from reductions in systematics and from incorporating higher-redshift sources (known and new) with high-resolution imaging.

astro-ph.CO↗