The Twins Embedding of Type Ia Supernovae II: Improving Cosmological Distance Estimates

Abstract

We show how spectra of Type Ia supernovae (SNe Ia) at maximum light can be used to improve cosmological distance estimates. In a companion article, we used manifold learning to build a three-dimensional parameterization of the intrinsic diversity of SNe Ia at maximum light that we call the "Twins Embedding". In this article, we discuss how the Twins Embedding can be used to improve the standardization of SNe Ia. With a single spectrophotometrically-calibrated spectrum near maximum light, we can standardize our sample of SNe Ia with an RMS of $0.101\pm 0.007$ mag, which corresponds to $0.084\pm 0.009$ mag if peculiar velocity contributions are removed and $0.073\pm 0.008$ mag if a larger reference sample were obtained. Our techniques can standardize the full range of SNe Ia, including those typically labeled as peculiar and often rejected from other analyses. We find that traditional light curve width + color standardization such as SALT2 is not sufficient. The Twins Embedding identifies a subset of SNe Ia including but not limited to 91T-like SNe Ia whose SALT2 distance estimates are biased by $0.229\pm 0.045$ mag. Standardization using the Twins Embedding also significantly decreases host-galaxy correlations. We recover a host mass step of $0.040\pm 0.020$ mag compared to $0.092\pm 0.024$ mag for SALT2 standardization on the same sample of SNe Ia. These biases in traditional standardization methods could significantly impact future cosmology analyses if not properly taken into account.

Accepted to ApJ

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Cited by in corpus (19)

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• ParSNIP: Generative Models of Transient Light Curves with Physics-Enabled Deep Learning
• The Twins Embedding of Type Ia Supernovae I: The Diversity of Spectra at Maximum Light
• Constraints on Cosmological Parameters with a Sample of Type Ia Supernovae from JWST
• Using 1991T/1999aa-like Type Ia Supernovae as Standardizable Candles
• Using Host Galaxy Spectroscopy to Explore Systematics in the Standardisation of Type Ia Supernovae
• Carnegie Supernova Project-II: Near-infrared spectral diversity and template of Type Ia Supernovae
• ZTF SN Ia DR2: Study of Type Ia Supernova lightcurve fits
• A Probabilistic Autoencoder for Type Ia Supernovae Spectral Time Series
• A Spectroscopic Model of the Type Ia Supernova--Host Galaxy Mass Correlation from SALT3
• Hawai'i Supernova Flows: A Peculiar Velocity Survey Using Over a Thousand Supernovae in the Near-Infrared
• Propagating Uncertainties in the SALT3 Model Training Process to Cosmological Constraints
• The Chicago Carnegie Hubble Program: Improving the Calibration of SNe Ia with JWST Measurements of the Tip of the Red Giant Branch
• Approaches to lowering the cost of large space telescopes
• The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust
• Normal or transitional? The evolution and properties of two type Ia supernovae in the Virgo cluster
• An Agnostic Approach to Building Empirical Type Ia Supernova Light Curves: Evidence for Intrinsic Chromatic Flux Variation Using Nearby Supernova Factory Data
• PISCOLA: a data-driven transient light-curve fitter
• A Sparse Spectroscopic Supernova Survey