Optical variability of QSOs and gravitational lenses in galactic haloes

Nature ◽  
1983 ◽  
Vol 301 (5899) ◽  
pp. 400-402 ◽  
Author(s):  
Roland Bacon ◽  
Jean-Luc Nieto
Keyword(s):  
Optical Variability ◽  
Gravitational Lenses ◽  
Galactic Haloes

Discovery of the fast optical variability of GRB 080319B and the prospects for wide-field optical monitoring with high time resolution

2010 ◽  
Vol 180 (4) ◽  
pp. 424 ◽  
Author(s):  
G.M. Beskin ◽  
S.V. Karpov ◽  
S.F. Bondar ◽  
V.L. Plokhotnichenko ◽  
A. Guarnieri ◽  
...  
Keyword(s):  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Optical Variability ◽  
Wide Field ◽  
Optical Monitoring

Redshifts of the Gravitational Lenses MG 0414+0534 and MG 0751+2716

1999 ◽  
Vol 117 (5) ◽  
pp. 2034-2038 ◽  
Author(s):  
John L. Tonry ◽  
Christopher S. Kochanek
Keyword(s):  
Gravitational Lenses

scholarly journals Fast automated analysis of strong gravitational lenses with convolutional neural networks

Nature ◽  
2017 ◽  
Vol 548 (7669) ◽  
pp. 555-557 ◽  
Author(s):  
Yashar D. Hezaveh ◽  
Laurence Perreault Levasseur ◽  
Philip J. Marshall
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Automated Analysis ◽  
Gravitational Lenses

scholarly journals Out of sight, out of mind? The impact of correlated clustering in substructure lensing

2021 ◽  
Author(s):  
Alexandres Lazar ◽  
James S Bullock ◽  
Michael Boylan-Kolchin ◽  
Robert Feldmann ◽  
Onur Çatmabacak ◽  
...  
Keyword(s):  
Dark Matter ◽  
Principal Axis ◽  
Major Axis ◽  
Line Of Sight ◽  
Gravitational Lenses ◽  
Local Clustering ◽  
Analytic Expression ◽  
Halo Masses ◽  
The Impact

Abstract A promising route for revealing the existence of dark matter structures on mass scales smaller than the faintest galaxies is through their effect on strong gravitational lenses. We examine the role of local, lens-proximate clustering in boosting the lensing probability relative to contributions from substructure and unclustered line-of-sight (LOS) haloes. Using two cosmological simulations that can resolve halo masses of Mhalo ≃ 109 M⊙ (in a simulation box of length Lbox ∼ 100 Mpc) and 107 M⊙ (Lbox ∼ 20 Mpc), we demonstrate that clustering in the vicinity of the lens host produces a clear enhancement relative to an assumption of unclustered haloes that persists to >20 Rvir. This enhancement exceeds estimates that use a two-halo term to account for clustering, particularly within 2 − 5 Rvir. We provide an analytic expression for this excess, clustered contribution. We find that local clustering boosts the expected count of 109 M⊙ perturbing haloes by ${\sim }35{{\ \rm per\ cent}}$ compared to substructure alone, a result that will significantly enhance expected signals for low-redshift (zl ≃ 0.2) lenses, where substructure contributes substantially compared to LOS haloes. We also find that the orientation of the lens with respect to the line of sight (e.g. whether the line of sight passes through the major axis of the lens) can also have a significant effect on the lensing signal, boosting counts by an additional $\sim 50{{\ \rm per\ cent}}$ compared to a random orientations. This could be important if discovered lenses are biased to be oriented along their principal axis.

scholarly journals Influence of Gravitational Lensing on Estimates of Ω in Neutral Hydrogen

1996 ◽  
Vol 173 ◽  
pp. 97-98
Author(s):  
Matthias Bartelmann ◽  
Abraham Loeb
Keyword(s):  
Observational Data ◽  
Gravitational Lensing ◽  
Column Density ◽  
Spiral Galaxies ◽  
Neutral Hydrogen ◽  
Absorption Lines ◽  
Gravitational Lenses ◽  
High Column

A wealth of observational data supports the commonly held view that damped Lyman-α (Lyα) absorption in QSO spectra is associated with neutral-hydrogen (HI) disks in spiral galaxies. Most of the HI probed by QSO absorption lines is traced by damped Lyα lines because of their high column densities, N > 1020 cm–2. The spiral galaxies hosting the HI disks can act as gravitational lenses on the QSOs. If the HI column density increases towards the center of the disks, as suggested by observations of local galaxies, the magnification bias preferentially selects for high column-density systems. The estimates of HI in damped Lyα systems can then systematically be distorted by gravitational lensing.

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