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The number of gravitational arcs systems detected is increasing quickly and should even increase at a faster rate in the near future. This wealth of new gravitational arcs requires the development of a purely automated method to reconstruct the lens and source. A general reconstruction method based on the singular perturbative approach is proposed in this paper. This method generates a lens and source reconstruction directly from the gravitational arc image. The method is fully automated and works in two steps. The first step is to generate a guess solution based on the circular solution in the singular perturbative approach. The second step is to break the sign degeneracy and to refine the solution by using a general source model. The refinement of the solution is conducted step-by-step to avoid the source-lens degeneracy issue. One important asset of this automated method is that the lens solution is written in universal terms which allows the computation of statistics. Considering the large number of lenses which should be available in the near future this ability to compute unbiased statistics is an important asset. [ABSTRACT FROM AUTHOR]

The Merian survey is mapping ∼ 850 deg2 of the Hyper Suprime-Cam Strategic Survey Program (HSC-SSP) wide layer with two medium-band filters on the 4-m Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory, with the goal of carrying the first high signal-to-noise (S/N) measurements of weak gravitational lensing around dwarf galaxies. This paper presents the design of the Merian filter set: N708 (λ c  = 7080 Å, Δλ = 275 Å) and N540 (λ c  = 5400 Å, Δλ = 210 Å). The central wavelengths and filter widths of N708 and N540 were designed to detect the |$\rm H\alpha$| and |$\rm [OIII]$| emission lines of galaxies in the mass range |$8\lt \rm \log M_*/M_\odot \lt 9$| by comparing Merian fluxes with HSC broad-band fluxes. Our filter design takes into account the weak lensing S/N and photometric redshift performance. Our simulations predict that Merian will yield a sample of ∼ 85 000 star-forming dwarf galaxies with a photometric redshift accuracy of σΔ z /(1 + z) ∼ 0.01 and an outlier fraction of |$\eta =2.8~{{\ \rm per\ cent}}$| over the redshift range 0.058 < z < 0.10. With 60 full nights on the Blanco/Dark Energy Camera (DECam), the Merian survey is predicted to measure the average weak lensing profile around dwarf galaxies with lensing S/N ∼32 within r < 0.5 Mpc and lensing S/N ∼90 within r < 1.0 Mpc. This unprecedented sample of star-forming dwarf galaxies will allow for studies of the interplay between dark matter and stellar feedback and their roles in the evolution of dwarf galaxies. [ABSTRACT FROM AUTHOR]

Strong gravitational lensing can be used to find otherwise invisible dark matter subhaloes. In such an analysis, the lens galaxy mass model is a significant source of systematic uncertainty. In this paper, we analyse the effect of angular complexity in the lens model. We use multipole perturbations that introduce low-order deviations from pure ellipticity in the isodensity contours, keeping the radial density profile fixed. We find that, in Hubble Space Telescope -like data, multipole perturbations consistent with those seen in galaxy isophotes are very effective at causing false positive substructure detections. We show that the effectiveness of this degeneracy depends on the deviation from a pure ellipse and the lensing configuration. We find that, when multipoles of 1 per cent are allowed in the lens model, the area in the observation where a subhalo could be detected drops by a factor of 3. Sensitivity away from the lensed images is mostly lost. However, the mass limit of detectable objects on or close to the lensed images does not change. We do not expect the addition of multipole perturbations to lens models to have a significant effect on the ability of strong lensing to constrain the underlying dark matter model. However, given the high rate of false positive detections, angular complexity beyond the elliptical power law should be included for such studies to be reliable. We discuss implications for previous detections and future work. [ABSTRACT FROM AUTHOR]

We have received a new physical characteristics fitting based on actual observational data from the Swift mission's long-duration gamma-ray bursts (LGRBs). We considered such characteristics as the Amati parameters for linear correlation (E iso– E p, i ) and the k -correction for gravitational lensing and Malmquist bias (GLMB) effect. We used the Pantheon SN Ia catalogue and the standard Lambda cold dark matter model with a fixed Hubble constant of H 0 = 70 km s−1 Mpc−1 as the baseline for the Hubble function μ(z). In our paper, we formulated the inverse cosmological calibration problem (ICCP) in the non-parametric statistics framework. The ICCP involves fitting non-observable physical characteristics while assuming a fixed cosmological model. To solve this problem, we developed a new method that is resistant to non-Gaussian processes. This method is based on error propagation through the Monte Carlo method and the Theil–Sen method for linear regression estimate. We have demonstrated the stability and robustness of this assessment method. The parameter estimates are as follows: |$a=0.92^{+0.12}_{-0.12}$|⁠ , |$b=50.32^{+0.33}_{-0.32}$| without considering the GLMB effect, and |$a=0.63^{+0.13}_{-0.14}$|⁠ , |$b=50.12^{+0.33}_{-0.31}$|⁠ , and |$k=1.98^{+0.25}_{-0.24}$| with the effect included. The proposed method can be applied to any other calibration sample of known standard candles, a calibrated sample of LGRBs, and the Hubble function μ(z). In the future, the ICCP idea can be used as an alternative cosmological test for estimating cosmological parameters, including the GLMB effect, or even for the selection of models, providing new information about the Universe. This can be done by analysing the residual values of observational data within the Bayesian statistics paradigm. [ABSTRACT FROM AUTHOR]

The article titled "Correction to: Redshift drift and strong gravitational lensing" acknowledges a mistake made in a recent paper by the author. The mistake relates to the measurement of the Hubble constant using the difference in redshift between images of a gravitational-lens system. The author clarifies that the redshift difference can still be used to measure other cosmological parameters without knowledge of the Hubble constant. The rest of the paper remains unaffected, discussing various aspects of standard cosmology and gravitational lensing. No new data is associated with the article. [Extracted from the article]