Precision cosmology with time delay lenses: high resolution imaging requirements

Meng, Xingmin; Treu, Tommaso; Agnello, Adriano; Auger, Matthew W.; Liao, Kai; Marshall, Phil

doi:10.1088/1475-7516/2015/09/059

Cited by 18 publications

(14 citation statements)

References 107 publications

(138 reference statements)

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“…While constraining the profile slope γ with better precision than the intrinsic scatter for individual lenses is possible, this would require high-resolution imaging from space or ground-based adaptive optics (e.g., Dye & Warren 2005;Chen et al 2016). Given the difficulties of measuring the power-law mass slope γ from seeing-limited groundbased images of lens systems (although see Meng et al 2015, for the optimisticscenario when various inputs are known perfectly such as the point spread function), we conclude that our network prediction for the delays has uncertainties comparable to that due to the unknown γ . We expect these two sources of uncertainties to be the dominant ones in ground-based images.…”

Section: Prediction Of Lensed Image Position(s) and Time-delay(s)mentioning

confidence: 95%

Holismokes

Schuldt

Suyu

Meinhardt

et al. 2021

A&A

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Modeling the mass distributions of strong gravitational lenses is often necessary in order to use them as astrophysical and cosmological probes. With the large number of lens systems (≳105) expected from upcoming surveys, it is timely to explore efficient modeling approaches beyond traditional Markov chain Monte Carlo techniques that are time consuming. We train a convolutional neural network (CNN) on images of galaxy-scale lens systems to predict the five parameters of the singular isothermal ellipsoid (SIE) mass model (lens center x and y, complex ellipticity ex and ey, and Einstein radius θE). To train the network we simulate images based on real observations from the Hyper Suprime-Cam Survey for the lens galaxies and from the Hubble Ultra Deep Field as lensed galaxies. We tested different network architectures and the effect of different data sets, such as using only double or quad systems defined based on the source center and using different input distributions of θE. We find that the CNN performs well, and with the network trained on both doubles and quads with a uniform distribution of θE > 0.5″ we obtain the following median values with 1σ scatter: Δx = (0.00−0.30+0.30)″, Δy = (0.00−0.29+0.30)″, ΔθE = (0.07−0.12+0.29)″, Δex = −0.01−0.09+0.08, and Δey = 0.00−0.09+0.08. The bias in θE is driven by systems with small θE. Therefore, when we further predict the multiple lensed image positions and time-delays based on the network output, we apply the network to the sample limited to θE > 0.8″. In this case the offset between the predicted and input lensed image positions is (0.00−0.29+0.29)″ and (0.00−0.31+0.32)″ for the x and y coordinates, respectively. For the fractional difference between the predicted and true time-delay, we obtain 0.04−0.05+0.27. Our CNN model is able to predict the SIE parameter values in fractions of a second on a single CPU, and with the output we can predict the image positions and time-delays in an automated way, such that we are able to process efficiently the huge amount of expected galaxy-scale lens detections in the near future.

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Section: Prediction Of Lensed Image Position(s) and Time-delay(s)mentioning

confidence: 95%

Holismokes

Schuldt

Suyu

Meinhardt

et al. 2021

A&A

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“…By requiring the uncertainty on the effective mass density profile slope to be equal to 0.02, the precision obtained by full-blown models, this procedure ensures that we get realistic uncertainties on distances. We know from full pixel-based simulations that such precision can be attained by modelling images obtained with reasonable exposure time using current and future technology (Meng et al 2015). A similar study is required to estimate the exposure times required to carry out the spectroscopic observations (Meng et al 2017, in preparation).…”

Section: Limitation Of This Present Workmentioning

confidence: 99%

Improving time-delay cosmography with spatially resolved kinematics

Shajib

Treu

Agnello

2017

Monthly Notices of the Royal Astronomical Society

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Strongly gravitational lensed quasars can be used to measure the so-called time-delay distance D ∆t , and thus the Hubble constant H 0 and other cosmological parameters. Stellar kinematics of the deflector galaxy play an essential role in this measurement by: (i) helping break the mass-sheet degeneracy; (ii) determining in principle the angular diameter distance D d to the deflector and thus further improving the cosmological constraints. In this paper we simulate observations of lensed quasars with integral field spectrographs and show that spatially resolved kinematics of the deflector enable further progress by helping break the mass-anisotropy degeneracy. Furthermore, we use our simulations to obtain realistic error estimates with current/upcoming instruments like OSIRIS on Keck and NIRSPEC on the James Webb Space Telescope for both distances (typically ∼ 6 per cent on D ∆t and ∼ 10 per cent on D d ). We use the error estimates to compute cosmological forecasts for the sample of nine lenses that currently have well measured time delays and deep Hubble Space Telescope images and for a sample of 40 lenses that is projected to be available in a few years through follow-up of candidates found in ongoing wide field surveys. We find that H 0 can be measured with 2 per cent (1 per cent) precision from nine (40) lenses in a flat Λcold dark matter cosmology. We study several other cosmological models beyond the flat Λcold dark matter model and find that time-delay lenses with spatially resolved kinematics can greatly improve the precision of the cosmological parameters measured by cosmic microwave background data.Gravitational lens systems where the source is variable in time provide a powerful direct measurement of distances, that is completely independent of the local distance ladder and the CMB (Refsdal 1964). Substantial progress in data quality, monitoring campaigns, and modelling techniques

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“…In practice, this is done using the code Pylens 5 written by one of us (M.W.A.) and functionally tested extensively by Meng et al (2015).…”

Section: Simulating High Resolution Noiseless Imagesmentioning

confidence: 99%

H0LiCOW. VI. Testing the fidelity of lensed quasar host galaxy reconstruction

Ding

Liao

Treu

et al. 2016

Mon. Not. R. Astron. Soc.

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The empirical correlation between the mass of a super-massive black hole (M BH ) and its host galaxy properties is widely considered to be evidence of their co-evolution. A powerful way to test the co-evolution scenario and learn about the feedback processes linking galaxies and nuclear activity is to measure these correlations as a function of redshift. Unfortunately, currently M BH can only be estimated in active galaxies at cosmological distances. At these distances, bright active galactic nuclei (AGN) can outshine the host galaxy, making it extremely difficult to measure the host's luminosity. Strongly lensed AGNs provide in principle a great opportunity to improve the sensitivity and accuracy of the host galaxy luminosity measurements as the host galaxy is magnified and more easily separated from the point source, provided the lens model is sufficiently accurate. In order to measure the M BH −L correlation with strong lensing, it is necessary to ensure that the lens modelling is accurate, and that the host galaxy luminosity can be recovered to at least a precision and accuracy better than that of the typical M BH measurement. We carry out extensive and realistic simulations of deep Hubble Space Telescope observations of lensed AGNs obtained by our collaboration. We show that the host galaxy luminosity can be recovered with better accuracy and precision than the typical uncertainty on M BH (∼ 0.5 dex) for hosts as faint as 2−4 magnitudes dimmer than the AGN itself. Our simulations will be used to estimate bias and uncertainties on the actual measurements to be presented in a future paper.

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Precision cosmology with time delay lenses: high resolution imaging requirements

Cited by 18 publications

References 107 publications

Holismokes

Holismokes

Improving time-delay cosmography with spatially resolved kinematics

H0LiCOW. VI. Testing the fidelity of lensed quasar host galaxy reconstruction

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