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 Studying Type II supernovae as cosmological standard candles using the Dark Energy Survey

2020 ◽  
Vol 495 (4) ◽  
pp. 4860-4892 ◽  
Author(s):  
T de Jaeger ◽  
L Galbany ◽  
S González-Gaitán ◽  
R Kessler ◽  
A V Filippenko ◽  
...  
Keyword(s):  
Dark Energy ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Distance Modulus ◽  
Type Ii ◽  
Hubble Diagram ◽  
Dark Energy Survey ◽  
Spectroscopic Information ◽  
Energy Survey

ABSTRACT Despite vast improvements in the measurement of the cosmological parameters, the nature of dark energy and an accurate value of the Hubble constant (H0) in the Hubble–Lemaître law remain unknown. To break the current impasse, it is necessary to develop as many independent techniques as possible, such as the use of Type II supernovae (SNe II). The goal of this paper is to demonstrate the utility of SNe II for deriving accurate extragalactic distances, which will be an asset for the next generation of telescopes where more-distant SNe II will be discovered. More specifically, we present a sample from the Dark Energy Survey Supernova Program (DES-SN) consisting of 15 SNe II with photometric and spectroscopic information spanning a redshift range up to 0.35. Combining our DES SNe with publicly available samples, and using the standard candle method (SCM), we construct the largest available Hubble diagram with SNe II in the Hubble flow (70 SNe II) and find an observed dispersion of 0.27 mag. We demonstrate that adding a colour term to the SN II standardization does not reduce the scatter in the Hubble diagram. Although SNe II are viable as distance indicators, this work points out important issues for improving their utility as independent extragalactic beacons: find new correlations, define a more standard subclass of SNe II, construct new SN II templates, and dedicate more observing time to high-redshift SNe II. Finally, for the first time, we perform simulations to estimate the redshift-dependent distance-modulus bias due to selection effects.

scholarly journals Superluminous supernovae from the Dark Energy Survey

2019 ◽  
Vol 487 (2) ◽  
pp. 2215-2241 ◽  
Author(s):  
C R Angus ◽  
M Smith ◽  
M Sullivan ◽  
C Inserra ◽  
P Wiseman ◽  
...  
Keyword(s):  
Dark Energy ◽  
Light Curve ◽  
Luminosity Function ◽  
High Redshift ◽  
Absolute Magnitude ◽  
Light Curves ◽  
Evolutionary Time ◽  
Dark Energy Survey ◽  
Monte Carlo Search ◽  
Energy Survey

ABSTRACT We present a sample of 21 hydrogen-free superluminous supernovae (SLSNe-I) and one hydrogen-rich SLSN (SLSN-II) detected during the five-year Dark Energy Survey (DES). These SNe, located in the redshift range 0.220 < z < 1.998, represent the largest homogeneously selected sample of SLSN events at high redshift. We present the observed g, r, i, z light curves for these SNe, which we interpolate using Gaussian processes. The resulting light curves are analysed to determine the luminosity function of SLSNe-I, and their evolutionary time-scales. The DES SLSN-I sample significantly broadens the distribution of SLSN-I light-curve properties when combined with existing samples from the literature. We fit a magnetar model to our SLSNe, and find that this model alone is unable to replicate the behaviour of many of the bolometric light curves. We search the DES SLSN-I light curves for the presence of initial peaks prior to the main light-curve peak. Using a shock breakout model, our Monte Carlo search finds that 3 of our 14 events with pre-max data display such initial peaks. However, 10 events show no evidence for such peaks, in some cases down to an absolute magnitude of <−16, suggesting that such features are not ubiquitous to all SLSN-I events. We also identify a red pre-peak feature within the light curve of one SLSN, which is comparable to that observed within SN2018bsz.

scholarly journals Supernova host galaxies in the dark energy survey: I. Deep coadds, photometry, and stellar masses

2020 ◽  
Vol 495 (4) ◽  
pp. 4040-4060 ◽  
Author(s):  
P Wiseman ◽  
M Smith ◽  
M Childress ◽  
L Kelsey ◽  
A Möller ◽  
...  
Keyword(s):  
Dark Energy ◽  
High Redshift ◽  
High Mass ◽  
Host Galaxy ◽  
Formation Mechanisms ◽  
Atmospheric Conditions ◽  
Host Galaxies ◽  
Dark Energy Survey ◽  
Stellar Masses ◽  
Energy Survey

ABSTRACT The 5-yr Dark Energy Survey Supernova Programme (DES-SN) is one of the largest and deepest transient surveys to date in terms of volume and number of supernovae. Identifying and characterizing the host galaxies of transients plays a key role in their classification, the study of their formation mechanisms, and the cosmological analyses. To derive accurate host galaxy properties, we create depth-optimized coadds using single-epoch DES-SN images that are selected based on sky and atmospheric conditions. For each of the five DES-SN seasons, a separate coadd is made from the other four seasons such that each SN has a corresponding deep coadd with no contaminating SN emission. The coadds reach limiting magnitudes of order ∼27 in g band, and have a much smaller magnitude uncertainty than the previous DES-SN host templates, particularly for faint objects. We present the resulting multiband photometry of host galaxies for samples of spectroscopically confirmed type Ia (SNe Ia), core-collapse (CCSNe), and superluminous (SLSNe) as well as rapidly evolving transients (RETs) discovered by DES-SN. We derive host galaxy stellar masses and probabilistically compare stellar-mass distributions to samples from other surveys. We find that the DES spectroscopically confirmed sample of SNe Ia selects preferentially fewer high-mass hosts at high-redshift compared to other surveys, while at low redshift the distributions are consistent. DES CCSNe and SLSNe hosts are similar to other samples, while RET hosts are unlike the hosts of any other transients, although these differences have not been disentangled from selection effects.

scholarly journals Detecting massive galaxies at high redshift using the Dark Energy Survey

2013 ◽  
Vol 434 (1) ◽  
pp. 296-312 ◽  
Author(s):  
L. J. M. Davies ◽  
C. Maraston ◽  
D. Thomas ◽  
D. Capozzi ◽  
R. H. Wechsler ◽  
...  
Keyword(s):  
Dark Energy ◽  
High Redshift ◽  
Massive Galaxies ◽  
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 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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