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Title: STRONG LENS TIME DELAY CHALLENGE. II. RESULTS OF TDC1

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. Seven teams participated in TDC1, submitting results from 78 different method variants. After describing each method, we compute and analyze basic statistics measuring accuracy (or bias) A, goodness of fit χ{sup 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 χ{sup 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 highermore » 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.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ; ; ;  [7] ;  [8] ;  [9] ; ;  [10] ; ;  [11] ;  [12] ;  [13] ; ;  [14] more »; « less
  1. Department of Astronomy, Beijing Normal University, Beijing 100875 (China)
  2. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
  3. Kavli Institute for Particle Astrophysics and Cosmology, P.O. Box 20450, MS29, Stanford, CA 94309 (United States)
  4. Department of Physics, University of California, 1 Shields Avenue, Davis, CA 95616 (United States)
  5. Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, CA 93106 (United States)
  6. Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of)
  7. EPFL, Lausanne (Switzerland)
  8. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)
  9. University of Manchester, School of Physics and Astronomy, Jodrell Bank Centre for Astrophysics, Manchester M13 9PL (United Kingdom)
  10. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  11. Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India)
  12. Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720 (United States)
  13. Department of Statistics, Harvard University, 1 Oxford Street, Cambridge, MA 02138 (United States)
  14. Jet Propulsion Laboratory, California Institute of Technology, M/S 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22364266
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 800; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; DATA ANALYSIS; DIAGRAMS; GRAVITATIONAL LENSES; TIME DELAY; VISIBLE RADIATION