Using 1991T/1999aa-like Type Ia Supernovae as Standardizable Candles

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