3 research outputs found
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µ* masses: weak-lensing calibration of the dark energy survey year 1 redMaPPer clusters using stellar masses
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 ~5.5 × 1013 M, 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-µz scaling relation given by M200c|µ, z = M0(µ5.16 × 1012 M)Fµ ((1 + z)/1.35)Gz. We find M0 = (1.14 ± 0.07) × 1014 M with Fµ= 0.76 ± 0.06 and Gz = -1.14 ± 0.37. We discuss the use of µ as a complementary mass proxy to the well-studied richness ? for: (i) exploring the regimes of low z, ? < 20 and high ?, z ~ 1; and (ii) testing systematics such as projection effects for applications in cluster cosmology
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First measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary–Black-hole Merger GW170814
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Multiwavelength optical and NIR variability analysis of the Blazar PKS 0027-426
We present multiwavelength spectral and temporal variability analysis of PKS 0027-426 using optical griz observations from Dark Energy Survey between 2013 and 2018 and VEILS Optical Light curves of Extragalactic TransienT Events (VOILETTE) between 2018 and 2019 and near-infrared (NIR) JKs observations from Visible and Infrared Survey Telescope for Astronomy Extragalactic Infrared Legacy Survey (VEILS) between 2017 and 2019. Multiple methods of cross-correlation of each combination of light curve provides measurements of possible lags between optical-optical, optical-NIR, and NIR-NIR emission, for each observation season and for the entire observational period. Inter-band time lag measurements consistently suggest either simultaneous emission or delays between emission regions on time-scales smaller than the cadences of observations. The colour-magnitude relation between each combination of filters was also studied to determine the spectral behaviour of PKS 0027-426. Our results demonstrate complex colour behaviour that changes between bluer when brighter, stable when brighter, and redder when brighter trends over different time-scales and using different combinations of optical filters. Additional analysis of the optical spectra is performed to provide further understanding of this complex spectral behaviour