scholarly journals Measuring gravitational lens time delays using low-resolution radio monitoring observations

2014 ◽  
Vol 441 (1) ◽  
pp. 127-135 ◽  
Author(s):  
G. Gürkan ◽  
N. Jackson ◽  
L. V. E. Koopmans ◽  
C. D. Fassnacht ◽  
A. Berciano Alba
Keyword(s):  
Time Delays ◽  
Gravitational Lens ◽  
Low Resolution ◽  
Radio Monitoring

scholarly journals Ambiguities in gravitational lens models: impact on time delays of the source position transformation

2018 ◽  
Vol 617 ◽  
pp. A140 ◽  
Author(s):  
Olivier Wertz ◽  
Bastian Orthen ◽  
Peter Schneider
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Hubble Constant ◽  
Companion Paper ◽  
Gravitational Lens ◽  
Source Position ◽  
Double Image ◽  
Validity Criterion ◽  
Mass Profile ◽  
Image Pairs

The central ambition of the modern time delay cosmography consists in determining the Hubble constant H0 with a competitive precision. However, the tension with H0 obtained from the Planck satellite for a spatially flat ΛCDM cosmology suggests that systematic errors may have been underestimated. The most critical of these errors probably comes from the degeneracy existing between lens models that was first formalized by the well-known mass-sheet transformation (MST). In this paper, we assess to what extent the source position transformation (SPT), a more general invariance transformation which contains the MST as a special case, may affect the time delays predicted by a model. To this aim, we have used pySPT, a new open-source python package fully dedicated to the SPT that we present in a companion paper. For axisymmetric lenses, we find that the time delay ratios between a model and its SPT-modified counterpart simply scale like the corresponding source position ratios, Δtˆ/Δt ≈ βˆ/β, regardless of the mass profile and the isotropic SPT. Similar behavior (almost) holds for nonaxisymmetric lenses in the double image regime and for opposite image pairs in the quadruple image regime. In the latter regime, we also confirm that the time delay ratios are not conserved. In addition to the MST effects, the SPT-modified time delays deviate in general no more than a few percent for particular image pairs, suggesting that its impact on time delay cosmography seems not be as crucial as initially suspected. We also reflected upon the relevance of the SPT validity criterion and present arguments suggesting that it should be reconsidered. Even though a new validity criterion would affect the time delays in a different way, we expect from numerical simulations that our conclusions will remain unchanged.

scholarly journals Gravitational lens time delays and gravitational waves

1994 ◽  
Vol 50 (8) ◽  
pp. 4895-4902 ◽  
Author(s):  
Joshua A. Frieman ◽  
Diego D. Harari ◽  
Gabriela C. Surpi
Keyword(s):  
Gravitational Waves ◽  
Time Delays ◽  
Gravitational Lens

scholarly journals The Quadruple Gravitational Lens PG 1115+080: Time Delays and Models

1997 ◽  
Vol 475 (2) ◽  
pp. L85-L88 ◽  
Author(s):  
Paul L. Schechter ◽  
Charles D. Bailyn ◽  
Robert Barr ◽  
Richard Barvainis ◽  
Christopher M. Becker ◽  
...  
Keyword(s):  
Time Delays ◽  
Gravitational Lens

scholarly journals Overconstrained gravitational lens models and the Hubble constant

2020 ◽  
Vol 493 (2) ◽  
pp. 1725-1735 ◽  
Author(s):  
C S Kochanek
Keyword(s):  
Power Law ◽  
Time Delays ◽  
Degrees Of Freedom ◽  
Hubble Constant ◽  
Gravitational Lens ◽  
Dark Matter Halo ◽  
Power Law Model ◽  
Dimensionless Quantity ◽  
Mean Convergence ◽  
The Mean

ABSTRACT It is well known that measurements of H0 from gravitational lens time delays scale as H0 ∝ 1 − κE, where κE is the mean convergence at the Einstein radius RE but that all available lens data other than the delays provide no direct constraints on κE. The properties of the radial mass distribution constrained by lens data are RE and the dimensionless quantity ξ = REα″(RE)/(1 − κE), where α″(RE) is the second derivative of the deflection profile at RE. Lens models with too few degrees of freedom, like power-law models with densities ρ ∝ r−n, have a one-to-one correspondence between ξ and κE (for a power-law model, ξ = 2(n − 2) and κE = (3 − n)/2 = (2 − ξ)/4). This means that highly constrained lens models with few parameters quickly lead to very precise but inaccurate estimates of κE and hence H0. Based on experiments with a broad range of plausible dark matter halo models, it is unlikely that any current estimates of H0 from gravitational lens time delays are more accurate than ${\sim} 10{{\ \rm per\ cent}}$, regardless of the reported precision.

scholarly journals COSMOLOGICAL CONSTRAINTS FROM GRAVITATIONAL LENS TIME DELAYS

2009 ◽  
Vol 706 (1) ◽  
pp. 45-59 ◽  
Author(s):  
Dan Coe ◽  
Leonidas A. Moustakas
Keyword(s):  
Time Delays ◽  
Gravitational Lens ◽  
Cosmological Constraints

scholarly journals Gravitational microlensing time delays at high optical depth: image parities and the temporal properties of fast radio bursts

2020 ◽  
Vol 497 (2) ◽  
pp. 1583-1589
Author(s):  
Geraint F Lewis
Keyword(s):  
Optical Depth ◽  
Gravitational Lensing ◽  
Time Delays ◽  
Saddle Points ◽  
Gravitational Lens ◽  
Depth Image ◽  
Short Time Scale ◽  
Solar Mass ◽  
Transient Sources ◽  
The Impact

ABSTRACT Due to differing gravitational potentials and path lengths, gravitational lensing induces time delays between multiple images of a source that, for solar mass objects, are of the order of ∼10−5 s. If an astrophysically compact source, such as a fast radio burst (FRB), is observed through a region with a high optical depth of such microlensing masses, this gravitational lensing time delay can be imprinted on short time-scale transient signals. In this paper, we consider the impact of the parity of the macroimage on the resultant microlensing time delays. It is found that this parity is directly imprinted on the microlensing signal, with macroimages formed at minima of the time arrival surface beginning with the most highly magnified microimages and then progressing to the fainter microimages. For macroimages at the maxima of the time arrival surface, this situation is reversed, with fainter images observed first and finishing with the brightest microimages. For macroimages at saddle points, the signal again begins with fainter images, followed by brighter images before again fading through the fainter microimages. The growing populations of cosmologically distant bursty transient sources will undoubtedly result in the discovery of strong lensed, multiply imaged FRBs, which will be susceptible to microlensing by compact masses. With the temporal resolution being offered by modern and future facilities, the detection of microlensing-induced time delays will reveal the parities of the gravitational lens macroimages, providing additional constraints on macrolensing mass models and improving the efficacy of these transient sources as cosmological probes.

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