Be It Unresolved: Measuring Time Delays from Lensed Supernovae

Alex G. Kim; Arman Shafieloo; Eric V. Linder; Satadru Bag

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Be It Unresolved: Measuring Time Delays from Lensed Supernovae

Satadru Bag, Alex G. Kim, Eric V. Linder, Arman Shafieloo

Cosmology and Nongalactic Astrophysics · Submitted 8 Oct 2020

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim We develop a method that successfully identifies such systems, with a false positive rate of $\lesssim 5\%$, and measures the time delays with a completeness of $\gtrsim 93\%$ and with a bias of $\lesssim 0.5\%$ for $\Delta t_{\rm fit} \gtrsim 10$ days.

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arXiv ID2010.03774 (version 1)

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CitationAlex G. Kim, Arman Shafieloo, Eric V. Linder, Satadru Bag. "Be It Unresolved: Measuring Time Delays from Lensed Supernovae." arXiv:2010.03774 (2020). https://pith.science/paper/HGSHGYIM

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What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.66 · human participants 0.01 · controlled comparison 0.09 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.09 · mentions code or data availability 0.03.

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Gravitationally lensed Type Ia supernovae may be the next frontier in cosmic probes, able to deliver independent constraints on dark energy, spatial curvature, and the Hubble constant. Measurements of time delays between the multiple images become more incisive due to the standardized candle nature of the source, monitoring for months rather than years, and partial immunity to microlensing. While currently extremely rare, hundreds of such systems should be detected by upcoming time domain surveys. Even more will have the images spatially unresolved, with the observed lightcurve a superposition of time delayed image fluxes. We investigate whether unresolved images can be recognized as lensed sources given only lightcurve information, and whether time delays can be extracted robustly. We develop a method that successfully identifies such systems, with a false positive rate of $\lesssim 5\%$, and measures the time delays with a completeness of $\gtrsim 93\%$ and with a bias of $\lesssim 0.5\%$ for $\Delta t_{\rm fit} \gtrsim 10$ days.

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What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Gravitationally lensed Type Ia supernovae may be the next frontier in cosmic probes, able to deliver independent constraints on dark energy, spatial curvature, and the Hubble constant.	background 1.00	0.05	0.03	hedged possibility 1.00
s1	Measurements of time delays between the multiple images become more incisive due to the standardized candle nature of the source, monitoring for months rather than years, and partial immunity to microlensing.	background 0.98	0.10	0.04	asserted 0.99
s2	While currently extremely rare, hundreds of such systems should be detected by upcoming time domain surveys.	background 0.98	0.08	0.02	asserted 0.61
s3	Even more will have the images spatially unresolved, with the observed lightcurve a superposition of time delayed image fluxes.	background 0.94	0.07	0.03	asserted 0.76
s4	We investigate whether unresolved images can be recognized as lensed sources given only lightcurve information, and whether time delays can be extracted robustly.	contribution 0.66	0.46	0.04	unclear 0.44
s5	We develop a method that successfully identifies such systems, with a false positive rate of $\lesssim 5\%$, and measures the time delays with a completeness of $\gtrsim 93\%$ and with a bias of $\lesssim 0.5\%$ for $\Delta t_{\rm fit} \gtrsim 10$ days.	result 0.75	0.97	0.91	asserted 1.00

What kind of paper the classifier reports this is: method or tool 1.00 · evidence from simulation or computation 0.99.

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Original abstract

Gravitationally lensed Type Ia supernovae may be the next frontier in cosmic probes, able to deliver independent constraints on dark energy, spatial curvature, and the Hubble constant. Measurements of time delays between the multiple images become more incisive due to the standardized candle nature of the source, monitoring for months rather than years, and partial immunity to microlensing. While currently extremely rare, hundreds of such systems should be detected by upcoming time domain surveys. Even more will have the images spatially unresolved, with the observed lightcurve a superposition of time delayed image fluxes. We investigate whether unresolved images can be recognized as lensed sources given only lightcurve information, and whether time delays can be extracted robustly. We develop a method that successfully identifies such systems, with a false positive rate of $\lesssim 5\%$, and measures the time delays with a completeness of $\gtrsim 93\%$ and with a bias of $\lesssim 0.5\%$ for $\Delta t_{\rm fit} \gtrsim 10$ days.

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References

Forward citations

Cited by 3 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

OASIS: On-the-fly ASynchronous Image Stream classification -- Transformer-based models for the early detection of strongly lensed supernovae
astro-ph.IM 2026-10 accept novelty 6.0 of 10

Factorized attention (separating spatial and temporal interactions) gives lower classification loss than joint attention or a ConvLSTM baseline for causal, on-the-fly classification of asynchronous multi-band image streams.
A Spectroscopic Road Map for Cosmic Frontier: DESI, DESI-II, Stage-5
astro-ph.CO 2022-09 conditional novelty 4.0 of 10

The paper proposes a spectroscopic roadmap from DESI through a DESI-II upgrade to a Stage-5 survey of hundreds of millions of galaxies and stars, aimed at inflation, dark energy, neutrinos, and dark matter.
Cosmology with strong gravitational lenses
astro-ph.CO 2026-10 accept

Strong gravitational lensing provides a purely gravitational probe that measures H0 at 3% precision from 11 lensed quasars and hints at dark matter self-interaction from dense subhalos.

How the literature uses it

6 arXiv papers cite this in 18 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 12 sentences without a confident label

Builds on it 1 paper

This extends Paper 1 [ref] in this series by going beyond two image systems to allow four images and a more robust exploration of multiplicity, and using a complementary fitting method, also without a fixed source template.

Out of One, Many: Distinguishing Time Delays from Lensed Supernovae · Introduction · 1.00

Uses its method or tool 1 paper

Following the formulation by [ref] , the general parameters of each lensed image can be characterized by the relative magnification $μ_i ≡a_i / a_1$ and the relative time delay $Δt_i ≡t_i-t_1$.

Finding Strongly Lensed Supernovae from Blended Light Curves · Modeling the Lightcurve · 0.93

Cites it as support 2 papers

* A measured time delay satisfying [equation] a regime in which false positive rates are expected to be negligible based on previous simulation results [ref] .

Finding Strongly Lensed Supernovae from Blended Light Curves · Selection Criteria and Convergence Filtering · 0.98
High-statistics catalogs of spectroscopically discovered strong lensing systems will significantly increase the number of time-delay observations possible with LSST [ref] .

A Spectroscopic Road Map for Cosmic Frontier: DESI, DESI-II, Stage-5 · Discovery space · 0.98

Cites it as background 1 paper

Several strategies have been developed to identify LSNe, including direct detection of multiple images [ref] , magnification-based selection using standardized Type Ia luminosities [ref] , color–magnitude cuts [ref] , and light-curve-based methods for unresolved systems [ref] .

HOLISMOKES XXI: Detecting strongly lensed type Ia supernovae from time series of multi-band LSST-like imaging data -- Part II · Introduction · 0.98

What it cites · 29 sentences without a confident label

Uses the method or tool of 5 papers

After testing different smoothing methods we use the iterative smoothing algorithm with exponential kernel in [ref] (see also, [ref] ), with a smoothing scale of $12$ days.

Model independent tests of the standard cosmological model · Prior on time delay and magnification · 0.99
After testing different smoothing methods we use the iterative smoothing algorithm with exponential kernel in [ref] (see also, [ref] ), with a smoothing scale of $12$ days.

Crossing Statistic: Reconstructing the Expansion History of the Universe · Prior on time delay and magnification · 0.99
After testing different smoothing methods we use the iterative smoothing algorithm with exponential kernel in [ref] (see also, [ref] ), with a smoothing scale of $12$ days.

Fast and Reliable Time Delay Estimation of Strong Lens Systems Using Method of Smoothing and Cross-Correlation · Prior on time delay and magnification · 0.99

Uses data or values from 1 paper

For more sophisticated lensed SN simulations we employ the ZTF-Ia lensed SN simulations compiled in [ref] that fulfill the following criteria: 1) Light curve visually appears smooth (and the shape is `like a light curve'); 2) The system has a minimum of $200$ data points when combining $g$, $r$, $i$ bands (typically the $i$-band data points are much fewer than for the $g$, $r$ bands) and $0.5 ≤μ≡μ_2/μ_1 ≤2$, $≥10$ days.

Rates and Properties of Strongly Gravitationally Lensed Supernovae and their Host Galaxies in Time-Domain Imaging Surveys · Applied Tests on the Goldstein Set · 0.93

Cites as support 1 paper

(Indeed, [ref] have shown that the color, i.e. differences between filters, is insensitive to microlensing for much of the phase relevant to time delay estimation.) For the small image separations we consider here for unresolved lensed SN, microlensing effects between images may also be reduced.

Rates and Properties of Strongly Gravitationally Lensed Supernovae and their Host Galaxies in Time-Domain Imaging Surveys · Modeling the Lightcurve · 0.99

Cites as background 6 papers

Simulation studies of lensed SN with images brightening well separated in time, i.e. time delays of $≳60$ days, is discussed in [ref] .

Turning Gravitationally Lensed Supernovae into Cosmological Probes · Introduction · 0.90
Time delay distances derived from monitoring quasars over years or even a decade are in use as a cosmological probe [ref] .

Time Delay Cosmography · Introduction · 0.95
Time delay distances derived from monitoring quasars over years or even a decade are in use as a cosmological probe [ref] .

STRIDES: a 3.9 per cent measurement of the Hubble constant from the strong lens system DES J0408-5354 · Introduction · 0.95

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