Photometric study of the late-time near-infrared plateau in Type Ia supernovae. Issue 3 (20th March 2023)

• Record Type: Journal Article
• Authors: Deckers, M; Graur, O; Maguire, K; Shingles, L; Brennan, S J; Anderson, J P; Burke, J; Chen, T-W; Galbany, L; Grayling, M J P; Gutiérrez, C P; Harvey, L; Hiramatsu, D; Howell, D A; Inserra, C; Killestein, T; McCully, C; Müller-Bravo, T E; Nicholl, M; Newsome, M; Padilla Gonzalez, E; Pellegrino, C; Terreran, G; Terwel, J H; Toy, M; Young, D R
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 521:Issue 3(2023)
• Page Start: 4414
• Page End: 4430
• Publication Date: 2023-03-20
• Subjects: Surveys -- supernovae: general; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad841
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present an in-depth study of the late-time near-infrared plateau in Type Ia supernovae (SNe Ia), which occurs between 70 and 500 d. We double the existing sample of SNe Ia observed during the late-time near-infrared plateau with new observations taken with the Hubble Space Telescope, Gemini, New Technology Telescope, the 3.5-m Calar Alto Telescope, and the Nordic Optical Telescope. Our sample consists of 24 nearby SNe Ia at redshift < 0.025. We are able to confirm that no plateau exists in the Ks band for most normal SNe Ia. SNe Ia with broader optical light curves at peak tend to have a higher average brightness on the plateau in J and H, most likely due to a shallower decline in the preceding 100 d. SNe Ia that are more luminous at peak also show a steeper decline during the plateau phase in H . We compare our data to state-of-the-art radiative transfer models of nebular SNe Ia in the near-infrared. We find good agreement with the sub-Mch model that has reduced non-thermal ionization rates, but no physical justification for reducing these rates has yet been proposed. An analysis of the spectral evolution during the plateau demonstrates that the ratio of [Fe ii ] to [Fe iii ] contribution in a near-infrared filter determines the light curve evolution in said filter. We find that overluminous SNe decline slower during the plateau than expected from the trend seen for normal SNe Ia.