Strong Lens Time Delay Challenge: II. Results of TDC1

Abstract

We present the results of the first strong lens time delay challenge. The motivation, experimental design, and entry level challenge are described in a companion paper. This paper presents the main challenge, TDC1, which consisted of analyzing thousands of simulated light curves blindly. The observational properties of the light curves cover the range in quality obtained for current targeted efforts (e.g.,~COSMOGRAIL) and expected from future synoptic surveys (e.g.,~LSST), and include simulated systematic errors. \nteamsA\ teams participated in TDC1, submitting results from \nmethods\ different method variants. After a describing each method, we compute and analyze basic statistics measuring accuracy (or bias) $A$, goodness of fit ${\chi }^2$, precision $P$, and success rate $f$. For some methods we identify outliers as an important issue. Other methods show that outliers can be controlled via visual inspection or conservative quality control. Several methods are competitive, i.e., give $|A|<0.03$, $P<0.03$, and ${\chi }^2<1.5$, with some of the methods already reaching sub-percent accuracy. The fraction of light curves yielding a time delay measurement is typically in the range $f=$20--40\%. It depends strongly on the quality of the data: COSMOGRAIL-quality cadence and light curve lengths yield significantly higher $f$ than does sparser sampling. Taking the results of TDC1 at face value, we estimate that LSST should provide around 400 robust time-delay measurements, each with $P<0.03$ and $|A|<0.01$, comparable to current lens modeling uncertainties. In terms of observing strategies, we find that $A$ and $f$ depend mostly on season length, while P depends mostly on cadence and campaign duration.

referee's comments incorporated; to appear in ApJ

References in corpus (9)

• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Gravitational Lens Time Delays: A Statistical Assessment of Lens Model Dependences and Implications for the Global Hubble Constant
• The Spatial Structure of An Accretion Disk
• Model Independent Reconstruction of the Expansion History of the Universe and the Properties of Dark Energy
• Cosmological Constraints from Gravitational Lens Time Delays
• The Hubble constant inferred from 18 time-delay lenses
• Crossing Statistic: Reconstructing the Expansion History of the Universe
• Microlensing variability in time-delay quasars
• Next Generation Strong Lensing Time Delay Estimation with Gaussian Processes

Cited by in corpus (41)

• H0LiCOW V. New COSMOGRAIL time delays of HE0435-1223: $H_0$ to 3.8% precision from strong lensing in a flat $\Lambda$CDM model
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• COSMOGRAIL XVI: Time delays for the quadruply imaged quasar DES J0408-5354 with high-cadence photometric monitoring
• Microlensing Makes Lensed Quasar Time Delays Significantly Time Variable
• Strong lensing time-delay cosmography in the 2020s
• Over-constrained Gravitational Lens Models and the Hubble Constant
• Gravitationally lensed quasars in Gaia -- IV. 150 new lenses, quasar pairs, and projected quasars
• Strongly Lensed Transient Sources: A Review
• Measurements of the Hubble constant and cosmic curvature with quasars: ultra-compact radio structure and strong gravitational lensing
• TDCOSMO. IX. Systematic comparison between lens modelling software programs: time delay prediction for WGD 2038-4008
• TDCOSMO 2025: Cosmological constraints from strong lensing time delays
• The Magnificent Five Images of Supernova Refsdal: Time Delay and Magnification Measurements
• Toward an internally consistent astronomical distance scale
• Strongly Lensed Gravitational Waves and Electromagnetic Signals as Powerful Cosmic Rulers
• Kiloparsec-Scale Simulations of Star Formation in Disk Galaxies III. Structure and Dynamics of Filaments and Clumps in Giant Molecular Clouds
• Methods of Reverberation Mapping. I. Time-lag Determination by Measures of Randomness
• Revisiting the Hubble constant, spatial curvature and cosmography with time-delay and cosmic chronometer observations
• Prospects of strongly lensed repeating fast radio bursts: complementary constraints on dark energy evolution
• Hydrodynamic simulations of mechanical stellar feedback in a molecular cloud formed by thermal instability
• Complementary constraints on dark energy equation of state from strongly lensed gravitational wave
• Constraints on cosmic curvature with lensing time delays and gravitational waves
• Statistical strong lensing. II. Cosmology and galaxy structure with time-delay lenses
• Strongly lensed type Ia supernovae as a precise late-universe probe of measuring the Hubble constant and cosmic curvature
• A 4% measurement of $H_0$ using the cumulative distribution of strong-lensing time delays in doubly-imaged quasars
• Radio Monitoring Campaigns of Six Strongly Lensed Quasars
• Fast and Reliable Time Delay Estimation of Strong Lens Systems Using Method of Smoothing and Cross-Correlation
• Identifying lensed quasars and measuring their time-delays from unresolved light curves
• Discovering Strongly-lensed QSOs From Unresolved Light Curves
• Testing cosmic opacity with the combination of strongly lensed and unlensed supernova Ia
• TD-CARMA: Painless, accurate, and scalable estimates of gravitational-lens time delays with flexible CARMA processes
• Tailoring Strong Lensing Cosmographic Observations
• Chromatic Microlensing Time Delays
• Hydrodynamical Simulations of Colliding Jets
• Host group degeneracy in gravitational lensing time delay determination of $H_0$
• Strong Lensing of High-Energy Neutrinos
• Time Delay Anomalies of Fuzzy Gravitational Lenses
• A Review on Resolving the Hubble Tension via Late-Universe Physics
• Harnessing Unresolved Lensed Quasars: The Mathematical Foundation of the Fluctuation Curve
• Probing stellar-mass primordial black holes with type Ia supernova microlensing
• Detection of Unresolved Strongly Lensed Supernovae with 7-Dimensional Telescope
• Detecting dark matter substructure with lensed quasars in optical bands