A simple prescription for simulating and characterizing gravitational arcs

Furlanetto, C.; Santiago, B.; Makler, M.; Bom, C. de; Brandt, Carlos; Neto, A. Fausti; Ferreira, P. Castelo; Costa, L. N. da; Maia, M. A. G.

doi:10.1051/0004-6361/201220387

Cited by 12 publications

(18 citation statements)

References 40 publications

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“…Until recently, finding these rare lensed systems required deliberate searches through known galaxy over-densities where the probability of GL is higher (Smail et al 1997;Postman et al 2012;Furlanetto et al 2013). However, follow-up observations of the brightest sources in under-dense regions revealed evidence of GL (e.g., Chapman et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Herschel-ATLAS and ALMA

Messias

Dye

Nagar

et al. 2014

A&A

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Context. The submillimetre-bright galaxy population is believed to comprise, aside from local galaxies and radio-loud sources, intrinsically active star-forming galaxies, the brightest of which are lensed gravitationally. The latter enable studies at a level of detail beyond what is usually possible by the observation facility. Aims. This work focuses on one of these lensed systems, HATLAS J142935.3−002836 (H1429−0028), selected in the Herschel-ATLAS field. Gathering a rich, multi-wavelength dataset, we aim to confirm the lensing hypothesis and model the background source's morphology and dynamics, as well as to provide a full physical characterisation. Methods. Multi-wavelength high-resolution data is utilised to assess the nature of the system. A lensing-analysis algorithm that simultaneously fits different wavebands is adopted to characterise the lens. The background galaxy dynamical information is studied by reconstructing the 3D source plane of the ALMA CO (J:4 → 3) transition. Near-IR imaging from HST and Keck-AO allows to constrain rest-frame optical photometry independently for the foreground and background systems. Physical parameters (such as stellar and dust masses) are estimated via modelling of the spectral energy distribution taking source blending, foreground obscuration, and differential magnification into account. Results. The system comprises a foreground edge-on disk galaxy (at z sp = 0.218) with an almost complete Einstein ring around it. The background source (at z sp = 1.027) is magnified by a factor of μ ∼ 8−10 depending on wavelength. It is comprised of two components and a tens-of-kpc-long tidal tail resembling the Antennae merger. As a whole, the background source is a massive stellar system (1.32 +0.63−0.41 × 10 11 M ) forming stars at a rate of 394 ± 90 M yr −1 , and it has a significant gas reservoir M ISM = 4.6 ± 1.7 × 10 10 M . Its depletion time due to star formation alone is thus expected to be τ SF = M ISM /SFR = 117 ± 51 Myr. The dynamical mass of one of the components is estimated to be 5.8 ± 1.7 × 10 10 M , and, together with the photometric total mass estimate, it implies that H1429−0028 is a major merger system (1:2.8 +1.8 −1.5).

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Section: Introductionmentioning

confidence: 99%

Herschel-ATLAS and ALMA

Messias

Dye

Nagar

et al. 2014

A&A

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“…They found that, when applied to arcs originated from simple elliptical sources, the two methods lead to very similar results. Furlanetto et al (2013) recently presented some tools to model and fit gravitational arcs. Their ArcEllipse method models arc-like images analytically expressing arc shapes as the distortion of ellipses such as one of their main axes is bent into an arc of a circle.…”

Section: Improving the Interface Between Theory And Observationsmentioning

confidence: 99%

“…The arc is thus characterized by four parameters. To allow for asymmetries in the arc shape, Furlanetto et al (2013) suggest to split the length into the sum of a "right-hand" and of a "left-hand" lengths:…”

Section: Improving the Interface Between Theory And Observationsmentioning

confidence: 99%

“…the center of curvature of the arc, (x 0 , y 0 ). Again following the prescription of Furlanetto et al (2013), the brightness profile of the arc can be modeled assuming that the source generating the arc has an intrinsic Sersic (1968) brightness profile,…”

Section: Improving the Interface Between Theory And Observationsmentioning

confidence: 99%

“…Ciotti and Bertin 1999). Furlanetto et al (2013) apply this technique to both real and simulated arcs. They quantify how well their ArcEllipse+Sèrsic models can fit the data by means of the fit residuals.…”

Section: Improving the Interface Between Theory And Observationsmentioning

confidence: 99%

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Arc Statistics

Meneghetti

Bartelmann²,

Dahle

et al. 2013

Space Sci Rev

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The existence of an arc statistics problem was at the center of a strong debate in the last fifteen years. With the aim to clarify if the optical depth for giant gravitational arcs by galaxy clusters in the so called concordance model is compatible with observations, several studies were carried out which helped to significantly improve our knowledge of strong lensing clusters, unveiling their extremely complex internal structure. In particular, the abundance and the frequency of strong lensing events like gravitational arcs turned out to be a potentially very powerful tool to trace the structure formation. However, given the limited size of observational and theoretical data-sets, the power of arc statistics as a cosmological tool has been only minimally exploited so far. On the other hand, the last years were characterized by significant advancements in the field, and several cluster surveys that are ongoing or planned for the near future seem to have the potential to make arc statistics a competitive cosmological probe. Additionally, recent observations of anomalously large Einstein radii and concentrations in galaxy clusters have reinvigorated the debate on the arc statistics problem. In this paper, we review the work done so far on arc statistics, focussing on what is the lesson we learned and what is likely to improve in the next years.

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Analytic solutions for Navarro-Frenk-White lens models in the strong lensing regime for low characteristic convergences

Dúmet-Montoya

Caminha

Makler

2013

A&A

Self Cite

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Context. The Navarro-Frenk-White (NFW) density profile is often used to model gravitational lenses. For κ s 0.1 (where κ s is a parameter that defines the normalization of the NFW lens potential) -corresponding to galaxy and galaxy group mass scales -high numerical precision is required to accurately compute several quantities in the strong lensing regime. Aims. We obtain analytic solutions for several lensing quantities for circular NFW models and their elliptical (ENFW) and pseudoelliptical (PNFW) extensions, on the typical scales where gravitational arcs are expected to be formed, in the κ s 0.1 limit, by establishing their domain of validity. Methods. We approximate the deflection angle of the circular NFW model and derive analytic expressions for the convergence and shear for the PNFW and ENFW models. We obtain the constant distortion curves (including the tangential critical curve), which are used to define the domain of validity of the approximations, by employing a figure-of-merit to compare with the exact numerical solutions. We compute the deformation cross section as a further check of the validity of the approximations. Results. We derive analytic solutions for iso-convergence contours and constant distortion curves for the models considered here. We also obtain the deformation cross section, which is given in closed form for the circular NFW model and in terms of a one-dimensional integral for the elliptical ones. In addition, we provide a simple expression for the ellipticity of the iso-convergence contours of the pseudo-elliptical models and the connection of characteristic convergences among the PNFW and ENFW models. Conclusions. We conclude that the set of solutions derived here is generally accurate for κ s 0.1. For low ellipticities, values up to κ s 0.18 are allowed. On the other hand, the mapping among PNFW and the ENFW models is valid up to κ s 0.4. The solutions derived in this work can be used to speed up numerical codes and ensure their accuracy in the low κ s regime, including applications to arc statistics and other strong lensing observables.

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A simple prescription for simulating and characterizing gravitational arcs

Cited by 12 publications

References 40 publications

Herschel-ATLAS and ALMA

Herschel-ATLAS and ALMA

Arc Statistics

Analytic solutions for Navarro-Frenk-White lens models in the strong lensing regime for low characteristic convergences

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