"SNe Ia twins" in the Hubble flow, and the determination of H0

Abstract

We have applied our approach of using ''SNe Ia twins''in the Hubble flow to obtain distances to SNe Ia at z $>$ 0.015 and derive H$_{0}$. Our results, taking a single step between the low z domain and the Hubble flow, validate the three rung classical method. We find, however, that the full compilation of distances, both in Pantheon+ and in the Carnegie-Chicago Hubble Program (CCHP), contain some inaccurate values in the colors due to an underestimate of reddening by dust. This produces odd individual values for H$_{0}$ from single SNe Ia. On the average, those erroneous estimates do not affect the mean value of H$_{0}$, which is characterized by the bulk of well--modeled SNe Ia. Our sample of carefully addressed SNe Ia in the Hubble flow contains a dozen supernovae, for which the distances are determined with high accuracy. Three of these SNe Ia are of the Broad Line subtype and can be compared with SN 1989B in M66, a host galaxy with a unique convergence of the Cepheid distance determination and the Tip of the Red Giant Branch stars (TRGB) determination by the CCHP group. They point to a weighted average of H$_{0}$ $=$ 73.556 $\pm$ 2.084 (stat) km s$^{-1}$ Mpc $^{-1}$. There is as well a very good agreement on the distances to NGC 7250 and NGC 5643 between those derived with Cepheids by SH0ES and those derived with the use of J-Asymptotic Giant Branch stars (JAGB stars) by the CCHP, which makes them very good anchors. The sample of 12 SNe Ia gives a value of H$_{0}$ $=$ 72.833 $\pm$ 1.306(stat) $\pm$ 1.151 (sys) km s$^{-1}$ Mpc$^{-1}$, when anchored in Cepheids, and of H$_{0}$ $=$ 72.388 $\pm$ 1.272 (stat) $\pm$ 1.015 (sys) km s$^{-1}$ Mpc$^{-1}$, when anchored in JAGBs by the CCHP. We take a mean of the two values of H$_{0}$ and obtain H$_{0}$ $=$ 72.610 $\pm$ 1.289(stat) $\pm$ 1.085 (sys) km s$^{-1}$ Mpc$^{-1}$.

Figures (19)

• Figure 1: Top: Comparison of the spectrum at 14 days past maximum of SN 2012bo with that of SN 2013dy at the same phase. Middle below top: Comparison of the spectrum of SN 2012bo at 26 days past maximum of SN 2012bo with that of SN 2013dy at the same phase. Middle above bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance and relative intrinsic reddening of supernova SN 2012bo in relation to SN 2013dy. Bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance moduli and relative intrinsic reddening of supernova SN 2012bo in relation to SN 2013dy.
• Figure 2: Top: Comparison of the spectrum at 0 days past maximim of SN 2008bq with that of SN 2013dy at the same phase. Middle below top: Comparison of the spectrum at 5 days past maximum of SN 2008bq with that of SN 2013dy at the same phase. Middle above bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance and relative intrinsic reddening of supernova SN 2008bq in relation to SN 2013dy. Bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance moduli and relative intrinsic reddening of supernova SN 2008bq in relation to SN 2013dy.
• Figure 3: Top: Comparison of the early time spectrum of SN 2008bz with SN 2011fe at 4 days past maximum light. Middle below top: Comparison of the spectrum of SN 2008bz at 13 days past maximum with the corresponding spectrum of SN 2011fe. Middle above bottom : Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance and relative intrinsic reddening of supernova SN 2008bz in relation to SN 2011fe. Bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance moduli and relative intrinsic reddening of supernova SN 2008bz in relation to SN 2011fe.
• Figure 4: Top: Comparison of the spectrum of LSQ12fxd at 2 days before maximum with that of SN 2013dy in the same phase. Middle below top: Comparison of the spectrum of LSQ12fxd at 3.7 days past maximum with that of SN 2013dy. Middle above bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance and relative intrinsic reddening of supernova LSQ12fxd in relation to SN 2013dy. Bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance moduli and relative intrinsic reddening of supernova LSQ12fxd in relation to SN 2013dy.
• Figure 5: Top: Comparison of the early time spectrum of SN 2008bf with SN 2013aa at -2 days before maximum light. Middle below top: Comparison of the spectrum of SN 2008bf at 42 days past maximum with the corresponding spectrum of SN 2003aa. Middle above bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance and relative intrinsic reddening of supernova SN 2008bf in relation to SN 2013aa. Bottom: Corner plot with the posterior probability at 1$\sigma$, 2$\sigma$, 3$\sigma$ of distance moduli and relative intrinsic reddening of supernova SN 2008bf in relation to SN 2013aa.