Using 1991T/1999aa-like Type Ia Supernovae as Standardizable Candles Academic Article uri icon

abstract

  • Abstract We present the photometry of 16 91T/99aa-like Type Ia Supernovae (SNe Ia) observed by the Las Cumbres Observatory. We also use an additional set of 21 91T/99aa-like SNe Ia and 87 normal SNe Ia from the literature for an analysis of the standardizability of the luminosity of 91T/99aa-like SNe. We find that 91T/99aa-like SNe are 0.2 mag brighter than normal SNe Ia, even when fully corrected by the light-curve shapes and colors. The weighted rms of the 91T/99aa-like SNe (with z CMB > 0.01) Hubble residuals is 0.25 0.03 mag, suggesting that 91T/99aa-like SNe are also excellent relative distance indicators to 12%. We compare the Hubble residuals with the pseudo-equivalent width (pEW) of Si ii 6355 around the date of maximum brightness. We find that there is a broken linear correlation between those two measurements for our sample including both 91T/99aa-like and normal SNe Ia. As the pEW max (Si ii 6355) increases, the Hubble residual increases when pEW max (Si ii 6355) < 55.6 . However, the Hubble residual stays constant beyond this. Given that 91T/99aa-like SNe possess shallower Si ii lines than normal SNe Ia, the linear correlation at pEW max (Si ii 6355) < 55.6 can account for the overall discrepancy of Hubble residuals derived from the two subgroups. Such a systematic effect needs to be taken into account when using SNe Ia to measure luminosity distances.

published proceedings

  • ASTROPHYSICAL JOURNAL

altmetric score

  • 12.66

author list (cited authors)

  • Yang, J., Wang, L., Suntzeff, N., Hu, L., Aldoroty, L., Brown, P. J., ... Valenti, S.

citation count

  • 4

complete list of authors

  • Yang, Jiawen||Wang, Lifan||Suntzeff, Nicholas||Hu, Lei||Aldoroty, Lauren||Brown, Peter J||Krisciunas, Kevin||Arcavi, Iair||Burke, Jamison||Galbany, Lluis||Hiramatsu, Daichi||Hosseinzadeh, Griffin||Howell, D Andrew||McCully, Curtis||Pellegrino, Craig||Valenti, Stefano

publication date

  • October 2022