1712.05800
The Hubble constant from SN Refsdal
Vega-Ferrero, Diego, Miranda, Bernstein
HST observations from Dec 11 2015 detected the expected fifth counter image of SN Refsdal at z=1.49. In this letter, compare the time delay predictions from numerous models with the measured value derived by Kelly et al (2016) from very early data in the light curve of the SN Refsdal, and find a best value for H0=66±12 km/s/Mpc (68% CL), in excellent agreement with predictions from CMB and recent WL data + BAO + BBN (from DES). This is the first constraint on H0 derived from time delays between multiple lensed SN images, and the first with a galaxy cluster lens, so subject to systematic effects different from other time-delay H0 estimates. Additional time delay measurements from new multiply-image See will allow derivation of competitive constraints on H0.
1712.06209
Dark Energy Survey Year 1 results: measurement of the Baryon Acoustic Oscillation scale in the distributions of galaxies to redshift 1
DES Collaboration
Present angular diameter distance measurements obtained by locating the BAO scale in the distribution of galaxies selected from DES. Consider a sample of >1.3 million galaxies distributed over a footprint of 1318 deg^2 with 0.6<z<1 and a typical redshift uncertainty of 0.03(1+z). This sample was selected, as full described in a companion paper, using a color/magnitude selection that optimizes trade-offs between number density and z uncertainty. Investigate the BAO signal in the projected clustering using 3 conventions, the angular separation, the co-moving transverse separation, and spherical harmonics. Further, compare results obtained from template based and machine learning photo-z determinations. Use 1800 sims that approximate the sample in order to produce covariance matrices and all validation of the distance scale measurement methodology. Measure the angular diameter distance, D_A, at the effective z of the sample divided by the true physical scale of the BAO feature, r_d. Obtain close to a 4% distance measurement of D_A(z_eff=0.81)/r_d = 10.75±0.43. These results are consistent with the flat LCDM concordance cosmological model supported by numerous other recent experimental results.
No comments:
Post a Comment