Measuring the Properties of Dark Energy with Photometrically Classified Pan-STARRS Supernovae. I. Systematic Uncertainty from Core-collapse Supernova Contamination

Jones, D.O.; Scolnic, D.M.; Riess, A.G.; Kessler, R.; Rest, A.; Kirshner, R.P.; Berger, E.; Ortega, C.A.; Foley, R.J.; Chornock, R.; Challis, P.J.; Burgett, W.S.; Chambers, K.C.; Draper, P.W.; Flewelling, H.; Huber, M.E.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Wainscoat, R.J.; Waters, C.

doi:10.3847/1538-4357/aa767b

Measuring the Properties of Dark Energy with Photometrically Classified Pan-STARRS Supernovae. I. Systematic Uncertainty from Core-collapse Supernova Contamination

Jones, D.O.; Scolnic, D.M.; Riess, A.G.; Kessler, R.; Rest, A.; Kirshner, R.P.; Berger, E.; Ortega, C.A.; Foley, R.J.; Chornock, R.; Challis, P.J.; Burgett, W.S.; Chambers, K.C.; Draper, P.W.; Flewelling, H.; Huber, M.E.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Wainscoat, R.J.; Waters, C.

Authors

D.O. Jones

D.M. Scolnic

A.G. Riess

R. Kessler

A. Rest

R.P. Kirshner

E. Berger

C.A. Ortega

R.J. Foley

R. Chornock

P.J. Challis

W.S. Burgett

K.C. Chambers

P.W. Draper

H. Flewelling

M.E. Huber

N. Kaiser

R.-P. Kudritzki

Dr Nigel Metcalfe nigel.metcalfe@durham.ac.uk
Assistant Professor

R.J. Wainscoat

C. Waters

Abstract

The Pan-STARRS (PS1) Medium Deep Survey discovered over 5000 likely supernovae (SNe) but obtained spectral classifications for just 10% of its SN candidates. We measured spectroscopic host galaxy redshifts for 3147 of these likely SNe and estimate that ~1000 are Type Ia SNe (SNe Ia) with light-curve quality sufficient for a cosmological analysis. We use these data with simulations to determine the impact of core-collapse SN (CC SN) contamination on measurements of the dark energy equation of state parameter, w. Using the method of Bayesian Estimation Applied to Multiple Species (BEAMS), distances to SNe Ia and the contaminating CC SN distribution are simultaneously determined. We test light-curve-based SN classification priors for BEAMS as well as a new classification method that relies upon host galaxy spectra and the association of SN type with host type. By testing several SN classification methods and CC SN parameterizations on large SN simulations, we estimate that CC SN contamination gives a systematic error on w (${\sigma }_{w}^{{CC}}$) of 0.014, 29% of the statistical uncertainty. Our best method gives ${\sigma }_{w}^{{CC}}=0.004$, just 8% of the statistical uncertainty, but could be affected by incomplete knowledge of the CC SN distribution. This method determines the SALT2 color and shape coefficients, α and β, with ~3% bias. However, we find that some variants require α and β to be fixed to known values for BEAMS to yield accurate measurements of w. Finally, the inferred abundance of bright CC SNe in our sample is greater than expected based on measured CC SN rates and luminosity functions.

Citation

Jones, D., Scolnic, D., Riess, A., Kessler, R., Rest, A., Kirshner, R., …Waters, C. (2017). Measuring the Properties of Dark Energy with Photometrically Classified Pan-STARRS Supernovae. I. Systematic Uncertainty from Core-collapse Supernova Contamination. Astrophysical Journal, 843(1), Article 6. https://doi.org/10.3847/1538-4357/aa767b

Journal Article Type	Article
Acceptance Date	May 30, 2017
Online Publication Date	Jun 26, 2017
Publication Date	Jun 26, 2017
Deposit Date	Jul 18, 2017
Publicly Available Date	Jul 18, 2017
Journal	Astrophysical Journal
Print ISSN	0004-637X
Electronic ISSN	1538-4357
Publisher	American Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	843
Issue	1
Article Number	6
DOI	https://doi.org/10.3847/1538-4357/aa767b