scholarly journals Mass-sheet degeneracy, power-law models and external convergence: Impact on the determination of the Hubble constant from gravitational lensing

2013 ◽  
Vol 559 ◽  
pp. A37 ◽  
Author(s):  
Peter Schneider ◽  
Dominique Sluse
Keyword(s):  
Power Law ◽  
Gravitational Lensing ◽  
Hubble Constant

scholarly journals Systematic errors induced by the elliptical power-law model in galaxy-galaxy strong lens modeling

2021 ◽  
Author(s):  
Xiaoyue Cao ◽  
Ran Li ◽  
James Nightingale ◽  
Richard Massey ◽  
Andrew Robertson ◽  
...  
Keyword(s):  
Power Law ◽  
Gravitational Lensing ◽  
Time Delays ◽  
Hubble Space Telescope ◽  
Stellar Dynamics ◽  
Hubble Constant ◽  
Power Law Model ◽  
Mass Model ◽  
Mass Distributions ◽  
Model Mismatch

Abstract The elliptical power-law (EPL) mass model of the mass in a galaxy is widely used in strong gravitational lensing analyses. However, the distribution of mass in real galaxies is more complex. We quantify the biases due to this model mismatch by simulating and then analysing mock {\it Hubble Space Telescope} imaging of lenses with mass distributions inferred from SDSS-MaNGA stellar dynamics data. We find accurate recovery of source galaxy morphology, except for a slight tendency to infer sources to be more compact than their true size. The Einstein radius of the lens is also robustly recovered with 0.1\% accuracy, as is the global density slope, with 2.5\% relative systematic error, compared to the 3.4\% intrinsic dispersion. However, asymmetry in real lenses also leads to a spurious fitted `external shear' with typical strength, $\gamma_{\rm ext}=0.015$. Furthermore, time delays inferred from lens modelling without measurements of stellar dynamics are typically underestimated by $\sim$5\%. Using such measurements from a sub-sample of 37 lenses would bias measurements of the Hubble constant $H_0$ by $\sim$9\%. The next generation cosmography must use more complex lens mass models.

scholarly journals Strong gravitational lensing: relativity in action

2009 ◽  
Vol 5 (S261) ◽  
pp. 249-259
Author(s):  
Joachim Wambsganss
Keyword(s):  
Gravitational Lensing ◽  
Extrasolar Planets ◽  
Hubble Constant ◽  
Stellar Atmospheres ◽  
Gravitational Lens ◽  
Cosmological Distance Scale ◽  
Galaxy Halos ◽  
Guided Tour ◽  
Observational Science

AbstractDeflection of light by gravity was predicted by Einstein's Theory of General Relativity and observationally confirmed in 1919. In the following decades, various aspects of the gravitational lens effect were explored theoretically, among them measuring the Hubble constant from multiple images of a background source, making use of the magnifying effect as a gravitational telescope, or the possibility of a “relativistic eclipse” as a perfect test of GR. Only in 1979, gravitational lensing became an observational science when the first doubly imaged quasar was discovered. Today lensing is a booming part of astrophysics and cosmology. A whole suite of strong lensing phenomena have been investigated: multiple quasars, giant luminous arcs, Einstein rings, quasar microlensing, and galactic microlensing. The most recent lensing application is the detection of extrasolar planets. Lensing has contributed significant new results in areas as different as the cosmological distance scale, mass determination of galaxy clusters, physics of quasars, searches for dark matter in galaxy halos, structure of the Milky Way, stellar atmospheres and exoplanets. A guided tour through some of these applications will illustrate how gravitational lensing has established itself as a very useful universal astrophysical tool.

scholarly journals Towards a New Proposal for the Time Delay in Gravitational Lensing

2017 ◽  
Author(s):  
Marco Bonici ◽  
Nicola Alchera ◽  
Nicola Maggiore
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Percent Level ◽  
Hubble Constant ◽  
New Physics ◽  
Statistical Fluctuation ◽  
Beyond The Standard Model ◽  
A Value ◽  
The Standard Model

One application of the Cosmological Gravitational Lensing in General Relativity is the measurement of the Hubble constant H_0 using the time delay Delta t between multiple images of lensed quasars. This method has already been applied, obtaining a value of H_0 compatible with that obtained from the SNe 1A, but non compatible with that obtained studying the anisotropies of the CMB. This difference could be a statistical fluctuation or an indication of new physics beyond the Standard Model of Cosmology, so it desirable to improve the precision of the measurements. At the current technological capabilities it is possible to obtain H_0 to a percent level uncertainty, so a more accurate theoretical model could be necessary in order to increase the precision about the determination of H_0. The actual formula which relates Delta t with H_0 is approximated; in this paper we expose a proposal to go beyond the previous analysis and, within the context of a new model, we obtain a more precise formula than that present in the Literature.

scholarly journals Lens galaxies in the Illustris simulation: power-law models and the bias of the Hubble constant from time delays

2015 ◽  
Vol 456 (1) ◽  
pp. 739-755 ◽  
Author(s):  
Dandan Xu ◽  
Dominique Sluse ◽  
Peter Schneider ◽  
Volker Springel ◽  
Mark Vogelsberger ◽  
...  
Keyword(s):  
Power Law ◽  
Time Delays ◽  
Hubble Constant ◽  
Lens Galaxies

scholarly journals Analysis of the Angular Dependence of Time Delay in Gravitational Lensing

2018 ◽  
Author(s):  
Nicola Alchera ◽  
Marco Bonici ◽  
Roberta Cardinale ◽  
Alba Domi ◽  
Nicola Maggiore ◽  
...  
Keyword(s):  
Time Delay ◽  
Angular Dependence ◽  
Gravitational Potential ◽  
Gravitational Lensing ◽  
Degrees Of Freedom ◽  
Hubble Constant ◽  
Smoothness Condition ◽  
Central Potential ◽  
Alternative Formula

We consider an alternative formula for time delay in gravitational lensing. Imposing a smoothness condition on the gravitationally deformed paths followed by the photons from the source to the observer, we show that our formula displays the same degrees of freedom of the standard one. In addition to this, it is shown that the standard expression for time delay is recovered when small angles are involved. These two features strongly support the claim that the formula for time delay studied in this paper is the generalization to arbitrary angles of the standard one, which is valid at small angles. This could therefore result in a useful tool in view of softening the known discrepancy between the various estimates of the Hubble constant. As an aside, two interesting consequences of our proposal for time delay are discussed: the existence of a constraint on the gravitational potential generated by the lens and a formula for the mass of the lens in the case of central potential.

scholarly journals The Hubble constant from eight time-delay galaxy lenses

2020 ◽  
Vol 501 (1) ◽  
pp. 784-801 ◽  
Author(s):  
Philipp Denzel ◽  
Jonathan P Coles ◽  
Prasenjit Saha ◽  
Liliya L R Williams
Keyword(s):  
Time Delay ◽  
Hubble Constant ◽  
Free Form ◽  
Microwave Background ◽  
Form Analysis ◽  
Systematic Uncertainties ◽  
Type Ia ◽  
Modelling Strategies ◽  
Supernovae Type Ia

ABSTRACT We present a determination of the Hubble constant from the joint, free-form analysis of eight strongly, quadruply lensing systems. In the concordance cosmology, we find $H_0{} = 71.8^{+3.9}_{-3.3}\, \mathrm{km}\, \mathrm{s}^{-1}\, \mathrm{Mpc}^{-1}{}{}$ with a precision of $4.97{{\ \rm per\ cent}}$. This is in agreement with the latest measurements from supernovae Type Ia and Planck observations of the cosmic microwave background. Our precision is lower compared to these and other recent time-delay cosmography determinations, because our modelling strategies reflect the systematic uncertainties of lensing degeneracies. We furthermore are able to find reasonable lensed image reconstructions by constraining to either value of H0 from local and early Universe measurements. This leads us to conclude that current lensing constraints on H0 are not strong enough to break the ‘Hubble tension’ problem of cosmology.

Determination of an effect of 3-chlorophenol on hydroxyl radical generation during ozonation through kinetic study in the power law type

2004 ◽  
Vol 4 (5-6) ◽  
pp. 305-311
Author(s):  
Y.-H. Han ◽  
I. Koshiishi ◽  
H. Utsumi
Keyword(s):  
Power Law ◽  
Ozone Decomposition ◽  
Oh Radical ◽  
Catalytic Intermediates ◽  
Stable Adduct ◽  
Solution Proceeds ◽  
Radical Generation ◽  
Power Law Equation ◽  
The Relationship

Ozone decomposition in aqueous solution proceeds through a radical type chain mechanism. These reactions involve the very reactive and catalytic intermediates hydroxyl (OH) radical, O2− radical, HO2 radical, OH−, H2O2, etc. OH radical is proposed as an important factor in the ozonation of water. In the previous study, generation of OH radical in the ozonation of water containing 3-chlorophenol was mathematically evaluated. In this study, we estimated the kinetic equation for the effect of 3-chlorophenol on OH radical generation during ozonation using the power law equation, in order to analyze it more correctly. The OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The relationship between the ozone concentration, 3-chlorophenol content, and the initial velocity (ν0) of DMPO-OH generation was analyzed mathematically, and the following equation was obtained: ν0 (10−6 M/s)=(1.58×10−5)×[3-chlorophenol (10−6 M)]×[ozone (10−6 M)]2.40+(3.09×10−5)×[ozone (10−6 M)]1.72. The equation fitted very well with the experimental results, and square of the correlation coefficient was larger than 0.9.

scholarly journals Gravitational lensing of quasar 0957+561 and the determination of H0

1995 ◽  
Author(s):  
George Rhee ◽  
Gary Bernstein ◽  
Tony Tyson ◽  
Phil Fischer
Keyword(s):  
Gravitational Lensing
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