The DES Bright Arcs Survey: Hundreds of Candidate Strongly Lensed Galaxy Systems from the Dark Energy Survey Science Verification and Year 1 Observations

Abstract

We report the results of searches for strong gravitational lens systems in the Dark Energy Survey (DES) Science Verification and Year 1 observations. The Science Verification data span approximately 250 sq. deg. with a median i-band limiting magnitude for extended objects (10σ) of 23.0. The Year 1 data span approximately 2000 sq. deg. and have an i-band limiting magnitude for extended objects (10σ) of 22.9. As these data sets are both wide and deep, they are particularly useful for identifying strong gravitational lens candidates. Potential strong gravitational lens candidate systems were initially identified based on a color and magnitude selection in the DES The Astrophysical Journal Supplement Series, 232:15 (28pp), 2017 September https://doi.org/10.3847/1538-4365/aa8667 © 2017. The American Astronomical Society. All rights reserved.1 object catalogs or because the system is at the location of a previously identified galaxy cluster. Cutout images of potential candidates were then visually scanned using an object viewer and numerically ranked according to whether or not we judged them to be likely strong gravitational lens systems. Having scanned nearly 400,000 cutouts, we present 374 candidate strong lens systems, of which 348 are identified for the first time. We provide the R.A. and decl., the magnitudes and photometric properties of the lens and source objects, and the distance (radius) of the source(s) from the lens center for each system.

Strong gravitational lensing of explosive transients

“…In Figure 11, we show the relation between the frequency f and the (redshifted) lens mass (1 + z l )M that satisfy w = 1 for the case of a point mass lens. We note that the similar relation hold for other lens mass models, once M is replaced to the enclosed mass within the Einstein radius (see equation 36). The region below the line in Figure 11 corresponds to w < 1, and hence to the diffraction.…”

“…A large number of gravitationally lensed distant galaxies have also been discovered by deep imaging of central regions of massive clusters of galaxies [30][31][32]. Recently, more strong lens systems are being found in various surveys such as Gaia [33][34][35], Dark Energy Survey [36][37][38][39], Kilo-Degree Survey [40], Pan-STARRS1 [41], and Subaru Hyper Suprime-Cam survey [42,43].…”

An Extended Catalog of Galaxy–Galaxy Strong Gravitational Lenses Discovered in DES Using Convolutional Neural Networks

“…This would have yielded a purer sample for human inspection, at the cost of some completeness. Of the Diehl et al (2017) candidates, 16 high-quality candidates lay outside (redward) of our color cuts by up to 0.25 magnitudes, an indication that future searches would benefit from relaxing the criteria.…”

“…Although in decades past most strong lenses were discovered serendipitously or through visual inspection of an entire survey, the scale of modern surveys means a more targeted approach is required. Previous strategies have included searching catalogs for multiple blue sources near red ETGs (Diehl et al 2017), modeling all sources as strong lenses and testing for goodness of fit (Marshall et al 2009;Chan et al 2015); or recruiting citizen scientists to examine images in quantity (Marshall et al 2016;More et al 2016). Recently, many efforts have employed modern computer vision and machine learning techniques.…”

Survey of Gravitationally lensed Objects in HSC Imaging (SuGOHI) – V. Group-to-cluster scale lens search from the HSC–SSP Survey

“…HSC J2226+0041 at z ,spec = 0.647: This is a known lens system (Diehl et al 2017;Sonnenfeld et al 2018;Jacobs et al 2019). We measure a mean redshift of z = 1.897, from emission lines such Figure 6.…”