scholarly journals The mystery of photometric twins DES17X1boj and DES16E2bjy

2020 ◽  
Vol 494 (4) ◽  
pp. 5576-5589 ◽  
Author(s):  
M Pursiainen ◽  
C P Gutiérrez ◽  
P Wiseman ◽  
M Childress ◽  
M Smith ◽  
...  
Keyword(s):  
Dark Energy ◽  
Light Curve ◽  
Spiral Galaxy ◽  
High Velocity ◽  
Photometric Data ◽  
Light Curves ◽  
Curve Evolution ◽  
Physical Origin ◽  
Dark Energy Survey ◽  
Energy Survey

ABSTRACT We present an analysis of DES17X1boj and DES16E2bjy, two peculiar transients discovered by the Dark Energy Survey (DES). They exhibit nearly identical double-peaked light curves that reach very different maximum luminosities (Mr = −15.4 and −17.9, respectively). The light-curve evolution of these events is highly atypical and has not been reported before. The transients are found in different host environments: DES17X1boj was found near the nucleus of a spiral galaxy, while DES16E2bjy is located in the outskirts of a passive red galaxy. Early photometric data are well fitted with a blackbody and the resulting moderate photospheric expansion velocities (1800  km s−1 for DES17X1boj and 4800  km s−1 for DES16E2bjy) suggest an explosive or eruptive origin. Additionally, a feature identified as high-velocity Ca ii absorption ($v$ ≈ 9400 km s−1) in the near-peak spectrum of DES17X1boj may imply that it is a supernova. While similar light-curve evolution suggests a similar physical origin for these two transients, we are not able to identify or characterize the progenitors.

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 Candidate Periodically Variable Quasars from the Dark Energy Survey and the Sloan Digital Sky Survey

2020 ◽  
Author(s):  
Yu-Ching Chen ◽  
Xin Liu ◽  
Wei-Ting Liao ◽  
A Miguel Holgado ◽  
Hengxiao Guo ◽  
...  
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Detection Rate ◽  
Sloan Digital Sky Survey ◽  
Light Curves ◽  
Close Binary ◽  
Single Frequency ◽  
Dark Energy Survey ◽  
Sky Survey ◽  
Energy Survey

Abstract Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5M⊙) at high redshift for the first time. We find five candidates with significant (at >99.74% single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3× 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 years (i.e., 1–2 years in rest frame) having ∼4–6 cycles spanned by the observations. If all five candidates are periodically variable quasars, this translates into a detection rate of ${\sim }0.8^{+0.5}_{-0.3}$% or ${\sim }1.1^{+0.7}_{-0.5}$ quasar per deg2. Our detection rate is 4–80 times larger than those found by previous searches using shallower surveys over larger areas. This discrepancy is likely caused by differences in the quasar populations probed and the survey data qualities. We discuss implications on the future direct detection of low-frequency gravitational waves. Continued photometric monitoring will further assess the robustness and characteristics of these candidate periodic quasars to determine their physical origins.

scholarly journals First Cosmology Results Using Type Ia Supernovae from the Dark Energy Survey: Photometric Pipeline and Light-curve Data Release

2019 ◽  
Vol 874 (1) ◽  
pp. 106 ◽  
Author(s):  
D. Brout ◽  
M. Sako ◽  
D. Scolnic ◽  
R. Kessler ◽  
C. B. D’Andrea ◽  
...  
Keyword(s):  
Dark Energy ◽  
Light Curve ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Data Release ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

scholarly journals Dark Energy Survey Year 3 Results: Photometric Data Set for Cosmology

2021 ◽  
Vol 254 (2) ◽  
pp. 24
Author(s):  
I. Sevilla-Noarbe ◽  
K. Bechtol ◽  
M. Carrasco Kind ◽  
A. Carnero Rosell ◽  
M. R. Becker ◽  
...  
Keyword(s):  
Dark Energy ◽  
Photometric Data ◽  
Data Set ◽  
Dark Energy Survey ◽  
Energy Survey

scholarly journals Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology

2018 ◽  
Vol 235 (2) ◽  
pp. 33 ◽  
Author(s):  
A. Drlica-Wagner ◽  
I. Sevilla-Noarbe ◽  
E. S. Rykoff ◽  
R. A. Gruendl ◽  
B. Yanny ◽  
...  
Keyword(s):  
Dark Energy ◽  
Photometric Data ◽  
Data Set ◽  
Dark Energy Survey ◽  
Energy Survey

scholarly journals Dark energy survey internal consistency tests of the joint cosmological probes analysis with posterior predictive distributions

2021 ◽  
Vol 503 (2) ◽  
pp. 2688-2705
Author(s):  
C Doux ◽  
E Baxter ◽  
P Lemos ◽  
C Chang ◽  
A Alarcon ◽  
...  
Keyword(s):  
Dark Energy ◽  
Internal Consistency ◽  
Goodness Of Fit ◽  
Small Scale ◽  
P Value ◽  
Posterior Predictive Distribution ◽  
Data Set ◽  
Dark Energy Survey ◽  
Data Vector ◽  
Energy Survey

ABSTRACT Beyond ΛCDM, physics or systematic errors may cause subsets of a cosmological data set to appear inconsistent when analysed assuming ΛCDM. We present an application of internal consistency tests to measurements from the Dark Energy Survey Year 1 (DES Y1) joint probes analysis. Our analysis relies on computing the posterior predictive distribution (PPD) for these data under the assumption of ΛCDM. We find that the DES Y1 data have an acceptable goodness of fit to ΛCDM, with a probability of finding a worse fit by random chance of p = 0.046. Using numerical PPD tests, supplemented by graphical checks, we show that most of the data vector appears completely consistent with expectations, although we observe a small tension between large- and small-scale measurements. A small part (roughly 1.5 per cent) of the data vector shows an unusually large departure from expectations; excluding this part of the data has negligible impact on cosmological constraints, but does significantly improve the p-value to 0.10. The methodology developed here will be applied to test the consistency of DES Year 3 joint probes data sets.

scholarly journals KiDS+VIKING-450 and DES-Y1 combined: Cosmology with cosmic shear

2020 ◽  
Vol 638 ◽  
pp. L1 ◽  
Author(s):  
S. Joudaki ◽  
H. Hildebrandt ◽  
D. Traykova ◽  
N. E. Chisari ◽  
C. Heymans ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Gravitational Lensing ◽  
Error Model ◽  
Calibration Error ◽  
Microwave Background ◽  
Weak Gravitational Lensing ◽  
Dark Energy Survey ◽  
Cosmic Shear ◽  
Energy Survey

We present a combined tomographic weak gravitational lensing analysis of the Kilo Degree Survey (KV450) and the Dark Energy Survey (DES-Y1). We homogenize the analysis of these two public cosmic shear datasets by adopting consistent priors and modeling of nonlinear scales, and determine new redshift distributions for DES-Y1 based on deep public spectroscopic surveys. Adopting these revised redshifts results in a 0.8σ reduction in the DES-inferred value for S​8, which decreases to a 0.5σ reduction when including a systematic redshift calibration error model from mock DES data based on the MICE2 simulation. The combined KV450+DES-Y1 constraint on S8 = 0.762−0.024+0.025 is in tension with the Planck 2018 constraint from the cosmic microwave background at the level of 2.5σ. This result highlights the importance of developing methods to provide accurate redshift calibration for current and future weak-lensing surveys.

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