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Title: Photometric classification and redshift estimation of LSST Supernovae

Abstract

Supernova (SN) classification and redshift estimation using photometric data only have become very important for the Large Synoptic Survey Telescope (LSST), given the large number of SNe that LSST will observe and the impossibility of spectroscopically following up all the SNe. We investigate the performance of an SN classifier that uses SN colours to classify LSST SNe with the Random Forest classification algorithm. Our classifier results in an area-under-the-curve of 0.98 which represents excellent classification. We are able to obtain a photometric SN sample containing 99 percent SNe Ia by choosing a probability threshold. We estimate the photometric redshifts (photo-z) of SNe in our sample by fitting the SN light curves using the SALT2 model with nested sampling. We obtain a mean bias (⟨zphot - zspec⟩) of 0.012 with σ(z phot -z spec 1+z spec )=0.0294 σ(zphot-zspec1+zspec)=0.0294 without using a host-galaxy photo-z prior, and a mean bias (⟨zphot - zspec⟩) of 0.0017 with σ(z phot -z spec 1+z spec )=0.0116 σ(zphot-zspec1+zspec)=0.0116 using a host-galaxy photo-z prior. Assuming a flat ΛCDM model with Ωm = 0.3, we obtain Ωm of 0.305 ± 0.008 (statistical errors only), using the simulated LSST sample of photometric SNe Ia (with intrinsic scatter σint = 0.11)more » derived using our methodology without using host-galaxy photo-z prior. Our method will help boost the power of SNe from the LSST as cosmological probes.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1439475
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Monthly Notices of the Royal Astronomical Society; Journal Volume: 477; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
cosmology; general; observations-supernovae

Citation Formats

Dai, Mi, Kuhlmann, Steve, Wang, Yun, and Kovacs, Eve. Photometric classification and redshift estimation of LSST Supernovae. United States: N. p., 2018. Web. doi:10.1093/mnras/sty965.
Dai, Mi, Kuhlmann, Steve, Wang, Yun, & Kovacs, Eve. Photometric classification and redshift estimation of LSST Supernovae. United States. doi:10.1093/mnras/sty965.
Dai, Mi, Kuhlmann, Steve, Wang, Yun, and Kovacs, Eve. Thu . "Photometric classification and redshift estimation of LSST Supernovae". United States. doi:10.1093/mnras/sty965.
@article{osti_1439475,
title = {Photometric classification and redshift estimation of LSST Supernovae},
author = {Dai, Mi and Kuhlmann, Steve and Wang, Yun and Kovacs, Eve},
abstractNote = {Supernova (SN) classification and redshift estimation using photometric data only have become very important for the Large Synoptic Survey Telescope (LSST), given the large number of SNe that LSST will observe and the impossibility of spectroscopically following up all the SNe. We investigate the performance of an SN classifier that uses SN colours to classify LSST SNe with the Random Forest classification algorithm. Our classifier results in an area-under-the-curve of 0.98 which represents excellent classification. We are able to obtain a photometric SN sample containing 99 percent SNe Ia by choosing a probability threshold. We estimate the photometric redshifts (photo-z) of SNe in our sample by fitting the SN light curves using the SALT2 model with nested sampling. We obtain a mean bias (⟨zphot - zspec⟩) of 0.012 with σ(z phot -z spec 1+z spec )=0.0294 σ(zphot-zspec1+zspec)=0.0294 without using a host-galaxy photo-z prior, and a mean bias (⟨zphot - zspec⟩) of 0.0017 with σ(z phot -z spec 1+z spec )=0.0116 σ(zphot-zspec1+zspec)=0.0116 using a host-galaxy photo-z prior. Assuming a flat ΛCDM model with Ωm = 0.3, we obtain Ωm of 0.305 ± 0.008 (statistical errors only), using the simulated LSST sample of photometric SNe Ia (with intrinsic scatter σint = 0.11) derived using our methodology without using host-galaxy photo-z prior. Our method will help boost the power of SNe from the LSST as cosmological probes.},
doi = {10.1093/mnras/sty965},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 3,
volume = 477,
place = {United States},
year = {Thu Apr 19 00:00:00 EDT 2018},
month = {Thu Apr 19 00:00:00 EDT 2018}
}