Non-parametric inversion of strong lensing systems

Mon. Not. R. Astron. Soc.

Broadhurst

Zitrin

et al. 2015

We examine the latest data on the cluster MACSJ0717.5+3745 from the Hubble Frontier Fields campaign. The critically lensed area is the largest known of any lens and very irregular making it a challenge for parametric modelling. Using our Free-Form method we obtain an accurate solution, identify here many new sets of multiple images, doubling the number of constraints and improving the reconstruction of the dark matter distribution. Our reconstructed mass map shows several distinct central substructures with shallow density profiles, clarifying earlier work and defining well the relation between the dark matter distribution and the luminous and X-ray peaks within the critically lensed region. Using our free-form method, we are able to meaningfully subtract the mass contribution from cluster members to the deflection field to trace the smoothly distributed cluster dark matter distribution. We find 4 distinct concentrations, 3 of which are coincident with the luminous matter. The fourth peak has a significant offset from both the closest luminous and X-ray peaks. These findings, together with dynamical data from the motions of galaxies and gas will be important for uncovering the potentially important implications of this extremely massive and intriguing system.

Section: Reconstruction Methodsmentioning

confidence: 99%

“…The unknowns of the lensing problem are in general the surface mass density and the positions of the background sources. As shown in Diego et al (2005a), the strong lensing problem can be expressed as a system of linear equations that can be represented in a compact form,…”

Section: Reconstruction Methodsmentioning

confidence: 99%

Hubble Frontier Field free-form mass mapping of the massive multiple-merging cluster MACSJ0717.5+3745

Mon. Not. R. Astron. Soc.

Broadhurst

Zitrin

et al. 2015

“…The reader can find the details of the method in our previous papers (Diego et al 2005a(Diego et al , 2007(Diego et al , 2016Sendra et al 2014). Here we give a brief summary of the most essential elements.…”

Section: Lensing Reconstruction Algorithm; Wslap+mentioning

confidence: 99%

“…This elongation extends well beyond the virial radius of the cluster (Gruen et al 2013), but with an azimuthally averaged large scale massive profile that fits well the NFW form out to a radius of 2 Mpc/h (Umetsu et al 2015). In this paper, we make a strong lensing analysis of the deep new optical HFF data now completed for this cluster, using our general free-form lensing technique (Diego et al 2005a(Diego et al , 2007(Diego et al , 2016Sendra et al 2014). Our aim is to objectively identify new multiply lensed systems for understanding the properties of low luminosity galaxies in the high redshift Universe.…”

Section: Introductionmentioning

confidence: 99%

A free-form mass model of the Hubble Frontier Fields cluster AS1063 (RXC J2248.7−4431) with over one hundred constraints

Mon. Not. R. Astron. Soc.

Broadhurst

Wong

et al. 2016

We derive a free-form mass distribution for the massive cluster AS1063 (z=0.348) using the completed optical imaging from the Hubble Frontier Fields programme. Based on a subset of 11 multiply lensed systems with spectroscopic redshift we produce a lens model that is accurate enough to unveil new multiply lensed systems, totalling over a 100 arclets, and to estimate their redshifts geometrically. Consistency is found between this precise model and that obtained using only the subset of lensed sources with spectroscopically measured redshifts.Although a relatively large elongation of the mass distribution is apparent relative to the X-ray map, no significant offset is found between the centroid of our mass distribution and that of the X-ray emission map, suggesting a relatively relaxed state for this cluster. For the well resolved lensed images we provide detailed model comparisons to illustrate the precision of our model and hence the reliability of our de-lensed sources. A clear linear structure is associated with one such source extending 23 kpc in length, that could be an example of jet-induced star formation, at redshift z ≈ 3.1.

“…B.) and the various improvements implemented in the code can be found in the literature (Diego et al 2005(Diego et al , 2007(Diego et al , 2015Sendra et al 2014). Here is a brief summary of the basic steps.…”

Section: Diego Et Almentioning

confidence: 99%

“Refsdal” Meets Popper: Comparing Predictions of the Re-Appearance of the Multiply Imaged Supernova Behind MACSJ1149.5+2223

Treu

Brammer

et al. 2016

ApJ

Self Cite

108

161

Supernova "Refsdal," multiply imaged by cluster MACS1149.5+2223, represents a rare opportunity to make a true blind test of model predictions in extragalactic astronomy, on a timescale that is short compared to a human lifetime. In order to take advantage of this event, we produced seven gravitational lens models with five independent methods, based on Hubble Space Telescope (HST) Hubble Frontier Field images, along with extensive spectroscopic follow-up observations by HST, the Very Large and the Keck Telescopes. We compare the model predictions and show that they agree reasonably well with the measured time delays and magnification ratios between the known images, even though these quantities were not used as input. This agreement is encouraging, considering that the models only provide statistical uncertainties, and do not include additional sources of uncertainties such as structure along the line of sight, cosmology, and the mass sheet degeneracy. We then present the model predictions for the other appearances of supernova "Refsdal." A future image will reach its peak in the first half of 2016, while another image appeared between 1994 and 2004. The past image would have been too faint to be detected in existing archival images. The future image should be approximately one-third as bright as the brightest known image (i.e., H 25.7 AB » mag at peak and H 26.7 AB » mag six months before peak), and thus detectable in single-orbit HST images. We will find out soon whether our predictions are correct.