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Durham University

Department of Physics

Staff profile

Publication details for Dr Nigel Metcalfe

Scolnic, D., Rest, A., Riess, A., Huber, M. E., Foley, R. J., Brout, D., Chornock, R., Narayan, G., Tonry, J. L., Berger, E., Soderberg, A. M., Stubbs, C. W., Kirshner, R. P., Rodney, S., Smartt, S. J., Schlafly, E., Botticella, M. T., Challis, P., Czekala, I., Drout, M., Hudson, M. J., Kotak, R., Leibler, C., Lunnan, R., Marion, G. H., McCrum, M., Milisavljevic, D., Pastorello, A., Sanders, N. E., Smith, K., Stafford, E., Thilker, D., Valenti, S., Wood-Vasey, W. M., Zheng, Z., Burgett, W. S., Chambers, K. C., Denneau, L., Draper, P. W., Flewelling, H., Hodapp, K. W., Kaiser, N., Kudritzki, R.-P., Magnier, E. A., Metcalfe, N., Price, P. A., Sweeney, W., Wainscoat, R. & Waters, C. (2014). Systematic Uncertainties Associated with the Cosmological Analysis of the First Pan-STARRS1 Type Ia Supernova Sample. The Astrophysical Journal 795(1): 45.

Author(s) from Durham


We probe the systematic uncertainties from the 113 Type Ia supernovae (SN Ia) in the Pan-STARRS1 (PS1)
sample along with 197 SN Ia from a combination of low-redshift surveys. The companion paper by Rest et al.
describes the photometric measurements and cosmological inferences from the PS1 sample. The largest systematic
uncertainty stems from the photometric calibration of the PS1 and low-z samples. We increase the sample of
observed Calspec standards from 7 to 10 used to define the PS1 calibration system. The PS1 and SDSS-II
calibration systems are compared and discrepancies up to ∼0.02 mag are recovered. We find uncertainties in the
proper way to treat intrinsic colors and reddening produce differences in the recovered value of w up to 3%. We
estimate masses of host galaxies of PS1 supernovae and detect an insignificant difference in distance residuals of
the full sample of 0.037 ± 0.031 mag for host galaxies with high and low masses. Assuming flatness and including
systematic uncertainties in our analysis of only SNe measurements, we find w =−1.120+0.360 −0.206(Stat)+0.269 −0.291(Sys).
With additional constraints from Baryon acoustic oscillation, cosmic microwave background (CMB) (Planck) and
H0 measurements, we find w = −1.166+0.072 −0.069 and Ωm = 0.280+0.013 −0.012 (statistical and systematic errors added in
quadrature). The significance of the inconsistency with w = −1 depends on whether we use Planck or Wilkinson
Microwave Anisotropy Probe measurements of the CMB: wBAO+H0+SN+WMAP = −1.124+0.083 −0.065.