scholarly journals Weak lensing of Type Ia Supernovae from the Dark Energy Survey

2020 ◽  
Vol 496 (3) ◽  
pp. 4051-4059
Author(s):  
E Macaulay ◽  
D Bacon ◽  
R C Nichol ◽  
T M Davis ◽  
J Elvin-Poole ◽  
...  
Keyword(s):  
Dark Energy ◽  
Gravitational Lensing ◽  
Weak Lensing ◽  
Type Ia Supernovae ◽  
Light Curve Analysis ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Angular Correlation Function ◽  
Ia Supernovae ◽  
Energy Survey

ABSTRACT We consider the effects of weak gravitational lensing on observations of 196 spectroscopically confirmed Type Ia Supernovae (SNe Ia) from years 1 to 3 of the Dark Energy Survey (DES). We simultaneously measure both the angular correlation function and the non-Gaussian skewness caused by weak lensing. This approach has the advantage of being insensitive to the intrinsic dispersion of SNe Ia magnitudes. We model the amplitude of both effects as a function of σ8, and find σ8 =1.2$^{+0.9}_{-0.8}$. We also apply our method to a subsample of 488 SNe from the Joint Light-curve Analysis (JLA; chosen to match the redshift range we use for this work), and find σ8 =0.8$^{+1.1}_{-0.7}$. The comparable uncertainty in σ8 between DES–SN and the larger number of SNe from JLA highlights the benefits of homogeneity of the DES–SN sample, and improvements in the calibration and data analysis.

scholarly journals First cosmological results using Type Ia supernovae from the Dark Energy Survey: measurement of the Hubble constant

2019 ◽  
Vol 486 (2) ◽  
pp. 2184-2196 ◽  
Author(s):  
E Macaulay ◽  
R C Nichol ◽  
D Bacon ◽  
D Brout ◽  
T M Davis ◽  
...  
Keyword(s):  
Dark Energy ◽  
Hubble Constant ◽  
Type Ia Supernovae ◽  
Distance Measurements ◽  
Dark Energy Survey ◽  
Systematic Uncertainties ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey ◽  
Inverse Distance

ABSTRACT We present an improved measurement of the Hubble constant (H0) using the ‘inverse distance ladder’ method, which adds the information from 207 Type Ia supernovae (SNe Ia) from the Dark Energy Survey (DES) at redshift 0.018 < z < 0.85 to existing distance measurements of 122 low-redshift (z < 0.07) SNe Ia (Low-z) and measurements of Baryon Acoustic Oscillations (BAOs). Whereas traditional measurements of H0 with SNe Ia use a distance ladder of parallax and Cepheid variable stars, the inverse distance ladder relies on absolute distance measurements from the BAOs to calibrate the intrinsic magnitude of the SNe Ia. We find H0 = 67.8 ± 1.3 km s−1 Mpc−1 (statistical and systematic uncertainties, 68 per cent confidence). Our measurement makes minimal assumptions about the underlying cosmological model, and our analysis was blinded to reduce confirmation bias. We examine possible systematic uncertainties and all are below the statistical uncertainties. Our H0 value is consistent with estimates derived from the Cosmic Microwave Background assuming a ΛCDM universe.

scholarly journals First cosmology results using Type IA supernovae from the dark energy survey: effects of chromatic corrections to supernova photometry on measurements of cosmological parameters

2019 ◽  
Vol 485 (4) ◽  
pp. 5329-5344 ◽  
Author(s):  
J Lasker ◽  
R Kessler ◽  
D Scolnic ◽  
D Brout ◽  
D L Burke ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Critical Density ◽  
Transmission Function ◽  
Type Ia Supernovae ◽  
Distance Modulus ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

Abstract Calibration uncertainties have been the leading systematic uncertainty in recent analyses using Type Ia supernovae (SNe Ia) to measure cosmological parameters. To improve the calibration, we present the application of spectral energy distribution-dependent ‘chromatic corrections’ to the SN light-curve photometry from the Dark Energy Survey (DES). These corrections depend on the combined atmospheric and instrumental transmission function for each exposure, and they affect photometry at the 0.01 mag (1 per cent) level, comparable to systematic uncertainties in calibration and photometry. Fitting our combined DES and low-z SN Ia sample with baryon acoustic oscillation (BAO) and cosmic microwave background (CMB) priors for the cosmological parameters Ωm (the fraction of the critical density of the universe comprised of matter) and w (the dark energy equation of state parameter), we compare those parameters before and after applying the corrections. We find the change in w and Ωm due to not including chromatic corrections is −0.002 and 0.000, respectively, for the DES-SN3YR sample with BAO and CMB priors, consistent with a larger DES-SN3YR-like simulation, which has a w-change of 0.0005 with an uncertainty of 0.008 and an Ωm change of 0.000 with an uncertainty of 0.002. However, when considering samples on individual CCDs we find large redshift-dependent biases (∼0.02 in distance modulus) for SN distances.

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 First cosmology results using type Ia supernovae from the Dark Energy Survey: the effect of host galaxy properties on supernova luminosity

2020 ◽  
Vol 494 (3) ◽  
pp. 4426-4447 ◽  
Author(s):  
M Smith ◽  
M Sullivan ◽  
P Wiseman ◽  
R Kessler ◽  
D Scolnic ◽  
...  
Keyword(s):  
Dark Energy ◽  
Bias Correction ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Photometric Measurements ◽  
Ia Supernovae ◽  
Energy Survey

ABSTRACT We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by the Dark Energy Survey Supernova Program (DES-SN) and used in the first DES-SN cosmological analysis. For the DES-SN sample, when considering a 5D (z, x1, c, α, β) bias correction, we find evidence of a Hubble residual ‘mass step’, where SNe Ia in high-mass galaxies (>1010M⊙) are intrinsically more luminous (after correction) than their low-mass counterparts by $\gamma =0.040\pm 0.019$ mag. This value is larger by 0.031 mag than the value found in the first DES-SN cosmological analysis. This difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. When using a 1D (redshift-only) bias correction the inferred mass step is larger, with $\gamma =0.066\pm 0.020$ mag. The 1D−5D γ difference for DES-SN is $0.026\pm 0.009$ mag. We show that this difference is due to a strong correlation between host galaxy stellar mass and the x1 component of the 5D distance-bias correction. Including an intrinsic correlation between the observed properties of SNe Ia, stretch and colour, and stellar mass in simulated SN Ia samples, we show that a 5D fit recovers γ with −9 mmag bias compared to a +2 mmag bias for a 1D fit. This difference can explain part of the discrepancy seen in the data. Improvements in modelling correlations between galaxy properties and SN is necessary to ensure unbiased precision estimates of the dark energy equation of state as we enter the era of LSST.

scholarly journals The Effect of Environment on Type Ia Supernovae in the Dark Energy Survey Three-Year Cosmological Sample

2020 ◽  
Author(s):  
L Kelsey ◽  
M Sullivan ◽  
M Smith ◽  
P Wiseman ◽  
D Brout ◽  
...  
Keyword(s):  
Dark Energy ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Sample Median ◽  
Star Forming ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

Abstract Analyses of type Ia supernovae (SNe Ia) have found puzzling correlations between their standardised luminosities and host galaxy properties: SNe Ia in high-mass, passive hosts appear brighter than those in lower-mass, star-forming hosts. We examine the host galaxies of SNe Ia in the Dark Energy Survey three-year spectroscopically-confirmed cosmological sample, obtaining photometry in a series of ‘local’ apertures centred on the SN, and for the global host galaxy. We study the differences in these host galaxy properties, such as stellar mass and rest-frame U − R colours, and their correlations with SN Ia parameters including Hubble residuals. We find all Hubble residual steps to be >3σ in significance, both for splitting at the traditional environmental property sample median and for the step of maximum significance. For stellar mass, we find a maximal local step of 0.098 ± 0.018 mag; ∼0.03 mag greater than the largest global stellar mass step in our sample (0.070 ± 0.017 mag). When splitting at the sample median, differences between local and global U − R steps are small, both ∼0.08 mag, but are more significant than the global stellar mass step (0.057 ± 0.017 mag). We split the data into sub-samples based on SN Ia light curve parameters: stretch (x1) and colour (c), finding that redder objects (c > 0) have larger Hubble residual steps, for both stellar mass and U − R, for both local and global measurements, of ∼0.14 mag. Additionally, the bluer (star-forming) local environments host a more homogeneous SN Ia sample, with local U − R r.m.s. scatter as low as 0.084 ± 0.017 mag for blue (c < 0) SNe Ia in locally blue U − R environments.

The Dark Energy Survey

2005 ◽  
Vol 20 (14) ◽  
pp. 3121-3123 ◽  
Author(s):  
◽  
Brenna Flaugher
Keyword(s):  
Dark Energy ◽  
Energy Equation ◽  
State Parameter ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Statistical Precision ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey ◽  
The Universe

Dark Energy is the dominant constituent of the universe and we have little understanding of it. We describe a new project aimed at measuring the dark energy equation of state parameter, w, to a statistical precision of ~5% with four separate techniques. The survey will image 5000 deg2 in the southern sky and collect 300 million galaxies, 30,000 galaxy clusters, and 2000 Type Ia supernovae. The survey will be carried out using a new 3 deg2 mosaic camera mounted at the prime focus of the 4m Blanco telescope at CTIO.

scholarly journals Type Ia supernovae selection and forecast of cosmology constraints for the Dark Energy Survey

2013 ◽  
Vol 42 ◽  
pp. 52-61 ◽  
Author(s):  
Eda Gjergo ◽  
Jefferson Duggan ◽  
John D. Cunningham ◽  
Steve Kuhlmann ◽  
Rahul Biswas ◽  
...  
Keyword(s):  
Dark Energy ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

scholarly journals First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: Constraints on Cosmological Parameters

2019 ◽  
Vol 872 (2) ◽  
pp. L30 ◽  
Author(s):  
T. M. C. Abbott ◽  
S. Allam ◽  
P. Andersen ◽  
C. Angus ◽  
J. Asorey ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Type Ia Supernovae ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

scholarly journals An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts

2013 ◽  
Vol 30 ◽  
Author(s):  
C. Lidman ◽  
V. Ruhlmann-Kleider ◽  
M. Sullivan ◽  
J. Myzska ◽  
P. Dobbie ◽  
...  
Keyword(s):  
High Redshift ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Wide Field ◽  
Host Galaxies ◽  
Dark Energy Survey ◽  
Large Numbers ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

AbstractWe use the wide-field capabilities of the 2 degree field fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first 3 years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ks per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is z ~ 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the 3-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4-m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of the sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.

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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