TY - JOUR
T1 - Cosmological tests with strong gravitational lenses using Gaussian processes
AU - Yennapureddy, Manoj K.
AU - Melia, Fulvio
N1 - Funding Information:
Acknowledgements FM is grateful to the Instituto de Astrofísica de Canarias in Tenerife and to Purple Mountain Observatory in Nanjing, China for their hospitality while part of this research was carried out. FM is also grateful for partial support to the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists under Grant 2012T1J0011, and to the Chinese State Administration of Foreign Experts Affairs under Grant GDJ20120491013.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Strong gravitational lenses provide source/lens distance ratios Dobs useful in cosmological tests. Previously, a catalog of 69 such systems was used in a one-on-one comparison between the standard model, ΛCDM, and the Rh= ct universe, which has thus far been favored by the application of model selection tools to many other kinds of data. But in that work, the use of model parametric fits to the observations could not easily distinguish between these two cosmologies, in part due to the limited measurement precision. Here, we instead use recently developed methods based on Gaussian Processes (GP), in which Dobs may be reconstructed directly from the data without assuming any parametric form. This approach not only smooths out the reconstructed function representing the data, but also reduces the size of the 1 σ confidence regions, thereby providing greater power to discern between different models. With the current sample size, we show that analyzing strong lenses with a GP approach can definitely improve the model comparisons, producing probability differences in the range ∼ 10–30%. These results are still marginal, however, given the relatively small sample. Nonetheless, we conclude that the probability of Rh= ct being the correct cosmology is somewhat higher than that of ΛCDM, with a degree of significance that grows with the number of sources in the subsamples we consider. Future surveys will significantly grow the catalog of strong lenses and will therefore benefit considerably from the GP method we describe here. In addition, we point out that if the Rh= ct universe is eventually shown to be the correct cosmology, the lack of free parameters in the study of strong lenses should provide a remarkably powerful tool for uncovering the mass structure in lensing galaxies.
AB - Strong gravitational lenses provide source/lens distance ratios Dobs useful in cosmological tests. Previously, a catalog of 69 such systems was used in a one-on-one comparison between the standard model, ΛCDM, and the Rh= ct universe, which has thus far been favored by the application of model selection tools to many other kinds of data. But in that work, the use of model parametric fits to the observations could not easily distinguish between these two cosmologies, in part due to the limited measurement precision. Here, we instead use recently developed methods based on Gaussian Processes (GP), in which Dobs may be reconstructed directly from the data without assuming any parametric form. This approach not only smooths out the reconstructed function representing the data, but also reduces the size of the 1 σ confidence regions, thereby providing greater power to discern between different models. With the current sample size, we show that analyzing strong lenses with a GP approach can definitely improve the model comparisons, producing probability differences in the range ∼ 10–30%. These results are still marginal, however, given the relatively small sample. Nonetheless, we conclude that the probability of Rh= ct being the correct cosmology is somewhat higher than that of ΛCDM, with a degree of significance that grows with the number of sources in the subsamples we consider. Future surveys will significantly grow the catalog of strong lenses and will therefore benefit considerably from the GP method we describe here. In addition, we point out that if the Rh= ct universe is eventually shown to be the correct cosmology, the lack of free parameters in the study of strong lenses should provide a remarkably powerful tool for uncovering the mass structure in lensing galaxies.
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U2 - 10.1140/epjc/s10052-018-5746-8
DO - 10.1140/epjc/s10052-018-5746-8
M3 - Article
AN - SCOPUS:85044780448
VL - 78
JO - European Physical Journal C
JF - European Physical Journal C
SN - 1434-6044
IS - 3
M1 - 258
ER -