Tailoring strong lensing cosmographic observations

Abstract

Strong lensing time delay cosmography has excellent complementarity with other dark energy probes, and will soon have abundant systems detected. We investigate two issues in the imaging and spectroscopic followup required to obtain the time delay distance. The first is optimization of spectroscopic resources. We develop a code to optimize the cosmological leverage under the constraint of constant spectroscopic time, and find that sculpting the lens system redshift distribution can deliver a 40% improvement in dark energy figure of merit. The second is the role of systematics, correlated between different quantities of a given system or model errors common to all systems. We show how the levels of different systematics affect the cosmological parameter estimation, and derive guidance for the fraction of double image vs quad image systems to follow as a function of differing systematics between them.

H0LiCOW – I. H0 Lenses in COSMOGRAIL's Wellspring: program overview

“…Our H0LiCOW program aims to establish gravitational lens time delays as an independent and competitive probe of cosmology, and paves the way for determining H0 to 1% in the future. Given the hundreds, if not thousands, of timedelay lens systems that are expected to be discovered in ongoing and future surveys such as the Sloan Digital Sky Survey (e.g., Oguri et al 2006;Inada et al 2012;More et al 2016b), the Dark Energy Survey (e.g., Agnello et al 2015), the Hyper Suprime-Cam Survey (e.g., Chan et al 2016), the Kilo-Degree Survey (e.g., Napolitano et al 2015), Euclid and the Large Synoptic Survey Telescope (Oguri & Marshall 2010), and continuous advances in high-resolution imaging and spectroscopy in the current and next generation of telescopes for observational follow-up (Meng et al 2015;Linder 2015), the H0LiCOW program will provide the basis for extracting cosmological information from the wealth of strong lensing data sets. In particular, we expect the combination of facilities at different wavelengths such as the HST in the optical/near-infrared, James Webb Space Telescope in the infrared, large and extremely large telescopes with adaptive optics, the Atacama Large Millimeter/submilliter Array in the sub mm waveband, and the Square Kilometer Array in the radio, will be of great synergistic value for studying these fruitful lenses.…”

Ultra Fast Astronomy: Optimized Detection of Multimessenger Transients

“…We use two independent codes to carry out the optimization. One is the information analysis optimization code described in Linder (2015), adapted for the present observables and variables, that evaluates the change in merit with resource amount (observing time), bin by bin, selects the bin with weakest leverage, reduces that n i , and reallocates its time to other bins (hence changing n j ) in a fashion weighted by the merit per resource used. The other uses the interior point optimization algorithm which combines the resource constraint and the merit function using the barrier function approach (Weisstein 2021).…”

“…Astrophysically, such an optimization analysis has been carried out for strong gravitational lens surveys (Linder 2015) and supernova surveys (e.g. Huterer & Turner (2001); Frieman et al (2003)).…”

Time delay cosmography

“…These targets can be met with present technology, as it has already been demonstrated for a few systems (Tewes et al, 2013b;Suyu et al, 2013), and the observational requirements have been investigated for a variety of telescopes and configurations (Greene et al, 2013;Collett et al, 2013;Meng et al, 2015;Linder, 2015).…”