An improved standardization framework for Type II-P supernovae using a hierarchical Bayesian approach

@misc{holas2026improved,
  title = {{An improved standardization framework for Type II-P supernovae using a hierarchical Bayesian approach}},
  author = {A Holas and S Taubenberger and C Vogl and D Rubin and M Vincenzi and W Hillebrandt and G Aldering and P Antilogus and C Aragon and S Bailey and C Baltay and S Benitez-Herrera and S Bongard and K Boone and C Buton and G Csörnyei and Y Copin and S Dixon and M Fink and D Fouchez and E Gangler and R Gupta and B Hayden and E.E.O Ishida and A.G Kim and M Klauser and M Kowalski and M Kromer and D.K Küsters and J Nordin and R Pain and E Pecontal and R Pereira and S Perlmutter and K.A Ponder and D Rabinowitz and M Rigault and K Runge and M Sasdelli and C Saunders and G Smadja and N Suzuki and C Tao and R.C Thomas},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.39804},
  eprint = {2609.39804},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05786301v1},
}

TY  - UNPB
TI  - An improved standardization framework for Type II-P supernovae using a hierarchical Bayesian approach
AU  - A Holas
AU  - S Taubenberger
AU  - C Vogl
AU  - D Rubin
AU  - M Vincenzi
AU  - W Hillebrandt
AU  - G Aldering
AU  - P Antilogus
AU  - C Aragon
AU  - S Bailey
AU  - C Baltay
AU  - S Benitez-Herrera
AU  - S Bongard
AU  - K Boone
AU  - C Buton
AU  - G Csörnyei
AU  - Y Copin
AU  - S Dixon
AU  - M Fink
AU  - D Fouchez
AU  - E Gangler
AU  - R Gupta
AU  - B Hayden
AU  - E.E.O Ishida
AU  - A.G Kim
AU  - M Klauser
AU  - M Kowalski
AU  - M Kromer
AU  - D.K Küsters
AU  - J Nordin
AU  - R Pain
AU  - E Pecontal
AU  - R Pereira
AU  - S Perlmutter
AU  - K.A Ponder
AU  - D Rabinowitz
AU  - M Rigault
AU  - K Runge
AU  - M Sasdelli
AU  - C Saunders
AU  - G Smadja
AU  - N Suzuki
AU  - C Tao
AU  - R.C Thomas
PY  - 2026
DA  - 2026/09/30
PB  - HAL
DO  - 10.48550/arxiv.2609.39804
UR  - https://hal.science/hal-05786301v1
AB  - We use Type II-P supernovae (SNe II-P) observed as part of the Nearby Supernova Factory (SNfactory) experiment as standardizable candles to develop an improved standardization framework. The data consist of accurately flux-calibrated, host-subtracted spectrophotometry of low-redshift SNe II-P in the wavelength range 3200 < λ< 10000 unicodexC5. We develop an improved method to determine the expansion velocities of SNe II-P based on Gaussian Process regression. We extend the conventional standardized candle method (SCM) by an additional correction term containing the H_α absorption-to-emission ratio and a hierarchical Bayesian framework. We find that the additional correction improves the quality of the standardization, particularly around $30$ to $40$ days after the explosion. We are able to reduce the scatter of the Hubble-flow SNe II-P from $0.28$ mag down to $0.18$ mag compared to previous work. As an example application of this methodology we measure H_0 using a pre-existing calibrator sample of SNe~II having Cepheid- or TRGB-based distance moduli. We find a value of H_0 = 70.6^+4.5_−4.3 km s^−1 Mpc^−1, including only statistical uncertainty, corresponding to a precision of $6.2$%. We find variations of $1.4$ km s^−1 Mpc^−1 between hierarchical model variations --- well within our quoted statistical uncertainty. Without the additional correction term, we obtain H_0 = 73.0^+6.9_−6.1 km s^−1 Mpc^−1 ($8.9$% precision) highlighting the improved precision of our new methodology. We identify and discuss inconsistencies between the measured parent populations of the calibrator and Hubble-flow standardization characteristics --- present in this and literature samples --- that are not explained by a simple selection on magnitude and which will need to be improved upon as SN II-P samples grow.
ER  -