scholarly journals VLBA observations of the gravitational lens system B0218+357

1995 ◽  
Vol 274 (1) ◽  
pp. L5-L7 ◽  
Author(s):  
A. R. Patnaik ◽  
R. W. Porcas ◽  
I. W. A. Browne
Keyword(s):  
Gravitational Lens ◽  
Lens System

scholarly journals Can We Measure H0 with VLBI Observations of Gravitational Images?

1988 ◽  
Vol 129 ◽  
pp. 207-208
Author(s):  
E. E. Falco ◽  
M. V. Gorenstein ◽  
I. I. Shapiro
Keyword(s):  
Time Delay ◽  
Mass Distribution ◽  
Velocity Dispersion ◽  
Gravitational Lens ◽  
Lens System ◽  
Relative Time ◽  
Surface Mass ◽  
A Value ◽  
Vlbi Observations ◽  
The Difference

We have used the relative positions and magnifications of the A and B images in the gravitational lens system 0957+561, obtained from VLBI observations, to constrain a model for the surface mass distribution of the lens. With measurements of the difference ΔτBA in propagation times associated with A and B (the “relative time delay”) and of the velocity dispersion of the main lensing galaxy, both to be obtained, our model will yield a value for H0 with an uncertainty of ∼ 20% due mainly to uncertainties in our assumptions.

scholarly journals Inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics

2019 ◽  
Vol 631 ◽  
pp. A40 ◽  
Author(s):  
S. Schuldt ◽  
G. Chirivì ◽  
S. H. Suyu ◽  
A. Yıldırım ◽  
A. Sonnenfeld ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Gravitational Lens ◽  
Wide Field ◽  
Lens System ◽  
Matter Distribution ◽  
Mass Model ◽  
Luminous Matter ◽  
Dark Matter Distribution ◽  
Light Components

We present a detailed analysis of the inner mass structure of the Cosmic Horseshoe (J1148+1930) strong gravitational lens system observed with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the spectacular Einstein ring, this systems shows a radial arc. We obtained the redshift of the radial arc counterimage zs, r = 1.961 ± 0.001 from Gemini observations. To disentangle the dark and luminous matter, we considered three different profiles for the dark matter (DM) distribution: a power law profile, the Navarro, Frenk, and White (NFW) profile, and a generalized version of the NFW profile. For the luminous matter distribution, we based the model on the observed light distribution that is fitted with three components: a point mass for the central light component resembling an active galactic nucleus, and the remaining two extended light components scaled by a constant mass-to-light ratio (M/L). To constrain the model further, we included published velocity dispersion measurements of the lens galaxy and performed a self-consistent lensing and axisymmetric Jeans dynamical modeling. Our model fits well to the observations including the radial arc, independent of the DM profile. Depending on the DM profile, we get a DM fraction between 60% and 70%. With our composite mass model we find that the radial arc helps to constrain the inner DM distribution of the Cosmic Horseshoe independently of the DM profile.

scholarly journals Search for Radio Recombination Lines towards the Gravitational Lens PKS1830-211

2002 ◽  
Vol 199 ◽  
pp. 116-117
Author(s):  
N.R. Mohan ◽  
K.R. Anantharamaiah ◽  
W.M. Goss
Keyword(s):  
Flux Density ◽  
Emission Measure ◽  
Gravitational Lens ◽  
Lens System ◽  
Frequency Range ◽  
Ionized Gas ◽  
Density Measurements ◽  
Radio Recombination Lines ◽  
Upper Limits ◽  
Single Epoch

A search for radio recombination lines near 20 cm at z=0.193 and z=0.886 towards the gravitational lens system PKS1830-211 has yielded upper limits of |τL| ≤ 5 × 10−5 and ≤ 5 × 10−4 at the two redshifts respectively. Based on the non-detections, we derive upper limits to the emission measure of the ionized gas in the absorbing systems. We also present continuum flux density measurements over the frequency range 0.3—45 GHz made at a single epoch.

scholarly journals Gaia GraL: Gaia DR2 gravitational lens systems

2018 ◽  
Vol 618 ◽  
pp. A56 ◽  
Author(s):  
C. Ducourant ◽  
O. Wertz ◽  
A. Krone-Martins ◽  
R. Teixeira ◽  
J.-F. Le Campion ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Space Mission ◽  
Gravitational Lens ◽  
Model Parameters ◽  
Gravitational Lenses ◽  
Bayesian Modelling ◽  
Lens System ◽  
Data Release ◽  
Gaia Dr2 ◽  
Exhaustive List

Context. Thanks to its spatial resolution, the ESA/Gaia space mission offers a unique opportunity to discover new multiply imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions. Aims. In this paper, we address the detection of the known multiply imaged quasars from the Gaia Data Release 2 (DR2) and determine the astrometric and photometric properties of the individually detected images found in the Gaia DR2 catalogue. Methods. We have compiled an exhaustive list of quasar gravitational lenses from the literature to search for counterparts in the Gaia DR2. We then analysed the astrometric and photometric properties of these Gaia’s detections. To highlight the tremendous potential of Gaia at the sub-milliarcsecond level we finally performed a simple Bayesian modelling of the well-known gravitational lens system HE0435-1223, using Gaia DR2 and HST astrometry. Results. From 481 known multiply imaged quasars, 206 have at least one image found in the Gaia DR2. Among the 44 known quadruply imaged quasars of the list, 29 have at least one image in the Gaia DR2, 12 of which are fully detected (2MASX J01471020+4630433, HE 0435-1223, SDSS1004+4112, PG1115+080, RXJ1131-1231, 2MASS J11344050-2103230, 2MASS J13102005-1714579, B1422+231, J1606-2333, J1721+8842, WFI2033-4723, WGD2038-4008), eight have three counterparts, eight have two and one has only one. As expected, the modelling of HE0435-1223 shows that the model parameters are significantly better constrained when using Gaia astrometry compared to HST astrometry, in particular the relative positions of the background quasar source and the centroid of the deflector. The Gaia sub-milliarcsecond astrometry also significantly reduces the parameter correlations. Conclusions. Besides providing an up-to-date list of multiply imaged quasars and their detection in the Gaia DR2, this paper shows that more complex modelling scenarios will certainly benefit from Gaia sub-milliarcsecond astrometry.

A large arc in the gravitational lens system 0957 + 561

1993 ◽  
Vol 105 ◽  
pp. 816 ◽  
Author(s):  
G. M. Bernstein ◽  
J. A. Tyson ◽  
C. S. Kochanek
Keyword(s):  
Gravitational Lens ◽  
Lens System

scholarly journals H0LiCOW – X. Spectroscopic/imaging survey and galaxy-group identification around the strong gravitational lens system WFI 2033−4723

2019 ◽  
Vol 490 (1) ◽  
pp. 613-633 ◽  
Author(s):  
D Sluse ◽  
C E Rusu ◽  
C D Fassnacht ◽  
A Sonnenfeld ◽  
J Richard ◽  
...  
Keyword(s):  
Group Identification ◽  
Companion Paper ◽  
Gravitational Lens ◽  
Lens System ◽  
Photometric Redshifts ◽  
Galaxy Groups ◽  
Dark Energy Survey ◽  
Lens Position ◽  
Integral Field Spectrograph ◽  
Stellar Masses

ABSTRACT Galaxies and galaxy groups located along the line of sight towards gravitationally lensed quasars produce high-order perturbations of the gravitational potential at the lens position. When these perturbation are too large, they can induce a systematic error on H0 of a few per cent if the lens system is used for cosmological inference and the perturbers are not explicitly accounted for in the lens model. In this work, we present a detailed characterization of the environment of the lens system WFI 2033−4723 ($z_{\rm src} =\,$1.662, $z_{\rm lens}=\,$0.6575), one of the core targets of the H0LiCOW project for which we present cosmological inferences in a companion paper. We use the Gemini and ESO-Very Large telescopes to measure the spectroscopic redshifts of the brightest galaxies towards the lens, and use the ESO-MUSE integral field spectrograph to measure the velocity-dispersion of the lens ($\sigma _{\rm {los}}= 250^{+15}_{-21}$  km s−1) and of several nearby galaxies. In addition, we measure photometric redshifts and stellar masses of all galaxies down to i < 23 mag, mainly based on Dark Energy Survey imaging (DR1). Our new catalogue, complemented with literature data, more than doubles the number of known galaxy spectroscopic redshifts in the direct vicinity of the lens, expanding to 116 (64) the number of spectroscopic redshifts for galaxies separated by less than 3 arcmin (2 arcmin ) from the lens. Using the flexion-shift as a measure of the amplitude of the gravitational perturbation, we identify two galaxy groups and three galaxies that require specific attention in the lens models. The ESO MUSE data enable us to measure the velocity-dispersions of three of these galaxies. These results are essential for the cosmological inference analysis presented in Rusu et al.

scholarly journals VLBI Observations of Gravitational Lens Systems

1988 ◽  
Vol 129 ◽  
pp. 191-199
Author(s):  
Edwin L. Turner
Keyword(s):  
Gravitational Lens ◽  
Lens System ◽  
Additional Test ◽  
System A ◽  
Vlbi Observations ◽  
Vlbi Data ◽  
Cosmological Tests ◽  
Superluminal Expansion ◽  
Additional Constraints

Four specific and particularly powerful types of possible VLBI lens studies are discussed. First, comparison of mas scale structure in putative pairs of images separated by arc seconds can provide a powerful additional test of the lens hypothesis in specific candidate systems. Second, VLBI searches for lens systems with image separations too small for resolution by optical or VLA searches will limit (or even determine!) the cosmological density of condensed objects with individual masses ∼ 106M⊙. Third, study of multiply imaged superluminal expansion events will allow a determination of the light travel time delay between different images in a lens system, a quantity which is quite difficult to measure by other means but which would allow profound cosmological tests. Fourth, VLBI data can be used to determine relative image parities and even the full magnification matrix of various images in a lens system, thus providing powerful additional constraints on detailed lens models. Finally, the speculative possibility of detecting Galactic stellar lensing events using VLBI techniques is discussed.

scholarly journals A Cusp—Counting Formula For Caustics Due To Multiplane Gravitational Lensing

1996 ◽  
Vol 173 ◽  
pp. 281-282
Author(s):  
A. O. Petters
Keyword(s):  
Light Source ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Gravitational Lens ◽  
Source Plane ◽  
Lens System ◽  
Light Rays ◽  
Counting Formula

Consider a gravitational lens system with K planes. If light rays are traced back from the observer to the light source plane, then the points on the first lens plane where a light ray either terminates, or, passes through and terminates before reaching the light source plane, are “obstruction points.” More precisely, tracing rays back to the source plane induces a K-plane lensing map η : U ⊆ R2 → R2 of the form η(x1) = x1 −∑i=1k αi(xi(xi)). We then define an obstruction point of η to be a point a of U where limx1→a |αi(xi(x1))| = ∞ for some “deflection angle” αi.

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