[Paper Review] Multi-color Optical and NIR Light Curves of 64 Stripped-Envelope Core-Collapse Supernovae

Bianco, F. B., Modjaz, M.+7 more|arXiv (Cornell University)|May 6, 2014

Gamma-ray bursts and supernovaePhysics and Astronomy142 citations

TL;DR

This study presents the most extensive multi-color optical and near-infrared (NIR) light curves of 64 low-redshift stripped-envelope core-collapse supernovae (SNe), collected between 2001 and 2009 at the Fred L. Whipple Observatory using template-subtracted photometry to minimize host galaxy contamination. The key contribution is the identification of distinct color trends—particularly a narrow r′−i′ color distribution for SN Ic-bl (σ = 0.01 mag) and a clear separation in r′−i′ vs. V−H color space—suggesting photometric classification of SN subtypes is feasible, especially with future NIR surveys.

ABSTRACT

We present a densely-sampled, homogeneous set of light curves of 64 low redshift (z < 0.05) stripped-envelope supernovae (SN of type IIb, Ib, Ic and Ic-bl). These data were obtained between 2001 and 2009 at the Fred L. Whipple Observatory (FLWO) on Mt. Hopkins in Arizona, with the optical FLWO 1.2-m and the near-infrared PAIRITEL 1.3-m telescopes. Our dataset consists of 4543 optical photometric measurements on 61 SN, including a combination of UBVRI, UBVr'i', and u'BVr'i', and 2142 JHKs near-infrared measurements on 25 SN. This sample constitutes the most extensive multi-color data set of stripped-envelope SN to date. Our photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination. This work presents these photometric data, compares them with data in the literature, and estimates basic statistical quantities: date of maximum, color, and photometric properties. We identify promising color trends that may permit the identification of stripped-envelope SN subtypes from their photometry alone. Many of these SN were observed spectroscopically by the CfA SN group, and the spectra are presented in a companion paper (Modjaz et al. 2014). A thorough exploration that combines the CfA photometry and spectroscopy of stripped-envelope core-collapse SN will be presented in a follow-up paper.

Motivation & Objective

• To compile a homogeneous, densely sampled photometric dataset of stripped-envelope SNe for statistical analysis.
• To address limitations in prior studies by using template-subtracted imaging to reduce host galaxy contamination.
• To enable photometric classification of SN Ib, Ic, and IIb subtypes without relying solely on spectroscopy.
• To support future large-scale transient surveys (e.g., LSST) by identifying photometric criteria for SN type identification.
• To provide a foundation for combined photometric and spectroscopic studies of SN progenitors and explosion mechanisms.

Proposed method

• Collected optical (UBVRI, u′BVr′i′) and NIR (JHKs) photometry using the FLWO 1.2-m and PAIRITEL 1.3-m telescopes between 2001 and 2009.
• Applied image template subtraction to all but the most isolated SNe to remove host galaxy light contamination.
• Calibrated photometry using standard stars and cross-verified with literature data.
• Used light curve fitting and color-color analysis to compare SN subtypes, focusing on peak brightness and color evolution.
• Integrated with spectroscopic data from M14 (Modjaz et al. 2014) to validate photometric trends.
• Evaluated data quality by comparing with D11 (Drout et al. 2011), identifying host contamination as a source of discrepancy in prior studies.

Experimental results

Research questions

• RQ1 Can multi-color optical and NIR light curves distinguish between SN Ib, Ic, IIb, and Ic-bl subtypes photometrically?
• RQ2 How do photometric color trends—particularly r′−i′ and V−H—vary across stripped-envelope SN subtypes?
• RQ3 To what extent does host galaxy contamination affect photometric light curves, and how can it be minimized?
• RQ4 Can the observed color distributions be used to classify SNe without spectroscopy, especially in upcoming wide-field surveys?
• RQ5 What are the statistical properties (e.g., peak magnitude, color dispersion) of SN Ic-bl, and how do they compare to other subtypes?

Key findings

• The dataset comprises 4,543 optical and 2,142 NIR photometric measurements of 64 stripped-envelope SNe, making it the largest such collection to date.
• SN Ic-bl exhibit a remarkably narrow r′−i′ color distribution at peak, with a standard deviation of only 0.01 mag around a mean of −0.025 mag.
• A clear separation in r′−i′ vs. V−H color space is observed, with SN Ic-bl appearing bluer than both SN Ib and Ic, though limited by low sample size (n=2 for Ic, n=2 for Ic-bl) near peak.
• Discrepancies with prior data (D11) are attributed to host galaxy contamination, as D11 did not use template subtraction, leading to photometry that is up to one magnitude brighter at peak.
• The study identifies several SNe with peculiar color behavior, including SN 2005la and SN 2006jc (spectroscopically known to interact with circumstellar material), and SN 2005kl (spectroscopically normal but photometrically anomalous).
• The dataset includes the first published photometry for 27 SNe and additional multi-band data for 37 previously studied SNe, significantly expanding the available photometric resource.