The Absolute Magnitudes of 1991T-like Supernovae

Abstract

1991T-like supernovae are the luminous, slow-declining extreme of the Branch shallow-silicon (SS) subclass of Type Ia supernovae. They are distinguished by extremely weak Ca II H & K and Si II $\lambda 6355$ and strong Fe III absorption features in their optical spectra at pre-maximum phases, and have long been suspected to be over-luminous compared to normal Type Ia supernovae. In this paper, the pseudo equivalent width of the Si II $\lambda$6355 absorption obtained at light curve phases from $\le +10$ days is combined with the morphology of the $i$-band light curve to identify a sample of 1991T-like supernovae in the Carnegie Supernova Project-II. Hubble diagram residuals show that, at optical as well as near-infrared wavelengths, these events are over-luminous by $\sim$0.1-0.5 mag with respect to the less extreme Branch SS (1999aa-like) and Branch core-normal supernovae with similar $B$-band light curve decline rates.

Submitted to ApJ (Aug 30, 2022)

References in corpus (14)

• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM
• The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
• Determining the Type, Redshift, and Age of a Supernova Spectrum
• PESSTO : survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects
• The Spectroscopic Diversity of Type Ia Supernovae
• The Carnegie Supernova Project: Intrinsic Colors of Type Ia Supernovae
• The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode as Deflagrations?
• Measuring the Hubble constant with Type Ia supernovae as near-infrared standard candles
• Comparative Direct Analysis of Type Ia Supernova Spectra. V. Insights from A Larger Sample and Quantitative Subclassification
• Abundance stratification in Type Ia Supernovae - IV: the luminous, peculiar SN 1991T
• Carnegie Supernova Project: The First Homogeneous Sample of "Super-Chandrasekhar Mass"/2003fg-like Type Ia Supernova
• Berkeley Supernova Ia Program: Data Release of 637 Spectra from 247 Type Ia Supernovae
• Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction

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