scholarly journals Spectroscopic Confirmation of Dark Energy Survey Strong Lensing Systems and Spectra for Photometric Redshift Calibration

2021 ◽  
Author(s):  
Elizabeth Buckley-Geer
Keyword(s):  
Dark Energy ◽  
Photometric Redshift ◽  
Dark Energy Survey ◽  
Strong Lensing ◽  
Energy Survey

scholarly journals Dark Energy Survey Year 1 results: validation of weak lensing cluster member contamination estimates from P(z) decomposition

2019 ◽  
Vol 489 (2) ◽  
pp. 2511-2524 ◽  
Author(s):  
T N Varga ◽  
J DeRose ◽  
D Gruen ◽  
T McClintock ◽  
S Seitz ◽  
...  
Keyword(s):  
Dark Energy ◽  
Decomposition Method ◽  
Weak Lensing ◽  
Cluster Member ◽  
Photometric Redshift ◽  
Cluster Mass ◽  
Dark Energy Survey ◽  
Mass Calibration ◽  
The Masses ◽  
Energy Survey

ABSTRACT Weak lensing source galaxy catalogues used in estimating the masses of galaxy clusters can be heavily contaminated by cluster members, prohibiting accurate mass calibration. In this study, we test the performance of an estimator for the extent of cluster member contamination based on decomposing the photometric redshift P(z) of source galaxies into contaminating and background components. We perform a full scale mock analysis on a simulated sky survey approximately mirroring the observational properties of the Dark Energy Survey Year One observations (DES Y1), and find excellent agreement between the true number profile of contaminating cluster member galaxies in the simulation and the estimated one. We further apply the method to estimate the cluster member contamination for the DES Y1 redMaPPer cluster mass calibration analysis, and compare the results to an alternative approach based on the angular correlation of weak lensing source galaxies. We find indications that the correlation based estimates are biased by the selection of the weak lensing sources in the cluster vicinity, which does not strongly impact the P(z) decomposition method. Collectively, these benchmarks demonstrate the strength of the P(z) decomposition method in alleviating membership contamination and enabling highly accurate cluster weak lensing studies without broad exclusion of source galaxies, thereby improving the total constraining power of cluster mass calibration via weak lensing.

scholarly journals On building a cluster watchlist for identifying strongly lensed supernovae, gravitational waves and kilonovae

2020 ◽  
Vol 495 (2) ◽  
pp. 1666-1671 ◽  
Author(s):  
Dan Ryczanowski ◽  
Graham P Smith ◽  
Matteo Bianconi ◽  
Richard Massey ◽  
Andrew Robertson ◽  
...  
Keyword(s):  
Dark Energy ◽  
Gravitational Waves ◽  
Lower Limit ◽  
High Redshift ◽  
Early Data ◽  
Source Plane ◽  
Dark Energy Survey ◽  
Strong Lensing ◽  
Cluster Properties ◽  
Energy Survey

ABSTRACT Motivated by discovering strongly lensed supernovae, gravitational waves, and kilonovae in the 2020s, we investigate whether to build a watchlist of clusters based on observed cluster properties (i.e. lens-plane selection) or on the detectability of strongly lensed background galaxies (i.e. source-plane selection). First, we estimate the fraction of high-redshift transient progenitors that reside in galaxies that are themselves too faint to be detected as being strongly lensed. We find ∼15–50 per cent of transient progenitors reside in z = 1 − 2 galaxies too faint to be detected in surveys that reach AB ≃ 23, such as the Dark Energy Survey. This falls to ≲10 per cent at depths that will be probed by early data releases of LSST (AB ≃ 25). Secondly, we estimate a conservative lower limit on the fraction of strong-lensing clusters that will be missed by magnitude-limited searches for multiply imaged galaxies and giant arcs due to the faintness of such images. We find that DES-like surveys will miss ∼75 per cent of 1015 M⊙ strong-lensing clusters, rising to ∼100 per cent of 1014 M⊙ clusters. Deeper surveys, such as LSST, will miss ∼40 per cent at 1015 M⊙ and ∼95 per cent at 1014 M⊙. Our results motivate building a cluster watchlist for strongly lensed transients that includes those found by the lens-plane selection.

scholarly journals Photometric redshift analysis in the Dark Energy Survey Science Verification data

2014 ◽  
Vol 445 (2) ◽  
pp. 1482-1506 ◽  
Author(s):  
C. Sánchez ◽  
M. Carrasco Kind ◽  
H. Lin ◽  
R. Miquel ◽  
F. B. Abdalla ◽  
...  
Keyword(s):  
Dark Energy ◽  
Photometric Redshift ◽  
Dark Energy Survey ◽  
Energy Survey

scholarly journals The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2017/2018 follow-up campaign: discovery of 10 lensed quasars and 10 quasar pairs

2020 ◽  
Vol 494 (3) ◽  
pp. 3491-3511 ◽  
Author(s):  
C Lemon ◽  
M W Auger ◽  
R McMahon ◽  
T Anguita ◽  
Y Apostolovski ◽  
...  
Keyword(s):  
Dark Energy ◽  
Near Infrared ◽  
Infrared Camera ◽  
Variable Component ◽  
Star Forming ◽  
Dark Energy Survey ◽  
Faint Object ◽  
Strong Lensing ◽  
Energy Survey

ABSTRACT We report the results of the STRong lensing Insights into the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates with ESO Faint Object Spectrograph and Camera 2 on the NTT and Echellette Spectrograph and Imager on Keck, confirming 10 new lensed quasars and 10 quasar pairs. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged (DESJ0345−2545, z = 1.68), and one is quadruply imaged (quad: DESJ0053−2012, z = 3.8). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on Southern Astrophysical Research Telescope or Near InfraRed Camera 2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcsec. After spectroscopic follow-up, we extract multi-epoch grizY photometry of confirmed lensed quasars and contaminant quasar + star pairs from DES data using parametric multiband modelling, and compare variability in each system’s components. By measuring the reduced χ2 associated with fitting all epochs to the same magnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems. Based on our spectroscopic follow-up, this variability information improves selection of lensed quasars and quasar pairs from 34-45 per cent to 51–70 per cent, with most remaining contaminants being star-forming galaxies. Using mock lensed quasar light curves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample, explained by the magnification bias and hence lower luminosity/more variable sources in quads.

scholarly journals μ⋆ masses: weak-lensing calibration of the Dark Energy Survey Year 1 redMaPPer clusters using stellar masses

2020 ◽  
Vol 498 (4) ◽  
pp. 5450-5467
Author(s):  
M E S Pereira ◽  
A Palmese ◽  
T N Varga ◽  
T McClintock ◽  
M Soares-Santos ◽  
...  
Keyword(s):  
Dark Energy ◽  
Weak Lensing ◽  
Cluster Member ◽  
Scaling Relation ◽  
Photometric Redshift ◽  
Dark Energy Survey ◽  
Source Sample ◽  
Stellar Masses ◽  
First Time ◽  
Energy Survey

ABSTRACT We present the weak-lensing mass calibration of the stellar-mass-based μ⋆ mass proxy for redMaPPer galaxy clusters in the Dark Energy Survey Year 1. For the first time, we are able to perform a calibration of μ⋆ at high redshifts, z > 0.33. In a blinded analysis, we use ∼6000 clusters split into 12 subsets spanning the ranges 0.1 ≤ z < 0.65 and μ⋆ up to ${\sim} 5.5 \times 10^{13} \, \mathrm{M}_{\odot }$, and infer the average masses of these subsets through modelling of their stacked weak-lensing signal. In our model, we account for the following sources of systematic uncertainty: shear measurement and photometric redshift errors, miscentring, cluster-member contamination of the source sample, deviations from the Navarro–Frenk–White halo profile, halo triaxiality, and projection effects. We use the inferred masses to estimate the joint mass–μ⋆–z scaling relation given by $\langle M_{200c} | \mu _{\star },z \rangle = M_0 (\mu _{\star }/5.16\times 10^{12} \, \mathrm{M_{\odot }})^{F_{\mu _{\star }}} ((1+z)/1.35)^{G_z}$. We find $M_0= (1.14 \pm 0.07) \times 10^{14} \, \mathrm{M_{\odot }}$ with $F_{\mu _{\star }}= 0.76 \pm 0.06$ and Gz = −1.14 ± 0.37. We discuss the use of μ⋆ as a complementary mass proxy to the well-studied richness λ for: (i) exploring the regimes of low z, λ < 20 and high λ, z ∼ 1; and (ii) testing systematics such as projection effects for applications in cluster cosmology.

scholarly journals Observation and confirmation of nine strong-lensing systems in Dark Energy Survey Year 1 data

2020 ◽  
Vol 494 (1) ◽  
pp. 1308-1322
Author(s):  
B Nord ◽  
E Buckley-Geer ◽  
H Lin ◽  
N Kuropatkin ◽  
T Collett ◽  
...  
Keyword(s):  
Dark Energy ◽  
Surface Brightness ◽  
Spectroscopic Properties ◽  
Source Image ◽  
Gravitational Lenses ◽  
Redshift Range ◽  
Photometric Redshift ◽  
Dark Energy Survey ◽  
Energy Survey

ABSTRACT We describe the observation and confirmation of nine new strong gravitational lenses discovered in Year 1 data from the Dark Energy Survey (DES). We created candidate lists based on (i) galaxy group and cluster samples, and (ii) photometrically selected galaxy samples. We selected 46 candidates through visual inspection and then used the Gemini Multi-Object Spectrograph(GMOS) at the Gemini South telescope to acquire a spectroscopic follow-up of 21 of these candidates. Through an analysis of these spectroscopic follow-up data, we confirmed nine new lensing systems and rejected two candidates, and the analysis was inconclusive on 10 candidates. For each of the confirmed systems, our report measured spectroscopic properties, estimated source image–lens separations, and estimated enclosed masses as well. The sources that we targeted have an i-band surface brightness range of $i_{\rm SB} \sim 22\!-\!24\, {\rm mag}\,{\rm arcsec}^{-2}$ and a spectroscopic redshift range of zspec ∼ 0.8−2.6. The lens galaxies have a photometric redshift range of zlens ∼ 0.3−0.7. The lensing systems range in source image–lens separation from 2 to 9 arcsec and in enclosed mass from 1012 to 1013 M⊙.

scholarly journals OBSERVATION AND CONFIRMATION OF SIX STRONG-LENSING SYSTEMS IN THE DARK ENERGY SURVEY SCIENCE VERIFICATION DATA

2016 ◽  
Vol 827 (1) ◽  
pp. 51 ◽  
Author(s):  
B. Nord ◽  
E. Buckley-Geer ◽  
H. Lin ◽  
H. T. Diehl ◽  
J. Helsby ◽  
...  
Keyword(s):  
Dark Energy ◽  
Dark Energy Survey ◽  
Strong Lensing ◽  
Energy Survey
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