Supernova type Ia luminosities, their dependence on second parameters, and the value of H_0

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dc.creatorParodi, B. R.
dc.creatorSaha, A.
dc.creatorSandage, A.
dc.creatorTammann, G. A.
dc.date2000-04-05
dc.date.accessioned2026-07-07T12:41:51Z
dc.date.available2026-07-07T12:41:51Z
dc.descriptionA sample of 35 SNe Ia with good to excellent photometry in B and V, minimum internal absorption, and 1200 < v < \approx 30000 km/s is compiled from the literature. As far as their spectra are known they are all Branch-normal. For 29 of the SNe Ia also peak magnitudes in I are known. The SNe Ia have uniform colors at maximum, i.e. <B-V>=-0.012 mag (sigma=0.051) and <V-I>=-0.276 mag (sigma=0.078). In the Hubble diagram they define a Hubble line with a scatter of $σ_M$=0.21-0.16 mag, decreasing with wavelength. The scatter is further reduced if the SNe Ia are corrected for differences in decline rate Delta_m_15 or color (B-V). A combined correction reduces the scatter to sigma<=0.13 mag. After the correction no significant dependence remains on Hubble type or galactocentric distance. The Hubble line suggests some curvature which can be differently interpreted. A consistent solution is obtained for a cosmological model with Omega_M=0.3, Omega_Lambda=0.7, which is indicated also by much more distant SNe Ia. Absolute magnitudes are available for eight equally blue (Branch-normal) SNe Ia in spirals, whose Cepheid distances are known. If their well defined mean values of M_B, M_V, and M_I are used to fit the Hubble line to the above sample of SNe Ia one obtains H_0=58.3 km/s/Mpc, or, after adjusting all SNe Ia to the average values of Delta_m_15 and (B-V), H_0=60.9 km/s/Mpc. Various systematic errors are discussed whose elimination tends to decrease H_0. The finally adopted value at the 90-percent level, including random and systematic errors, is H_0=58.5 +/- 6.3 km/s/Mpc. Several higher values of H_0 from SNe Ia, as suggested in the literature, are found to depend on large corrections for variations of the light curve parameter and/or on an unwarranted reduction of the Cepheid distances of the calibrating SNe Ia.
dc.description42 pages, including 9 figures; submitted to ApJ
dc.identifierhttps://arxiv.org/abs/astro-ph/0004063
dc.identifierhttp://arxiv.org/abs/astro-ph/0004063
dc.identifierAstrophys.J.540:634-651,1989
dc.identifierdoi:10.1086/309385
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/219881
dc.subjectAstrophysics
dc.titleSupernova type Ia luminosities, their dependence on second parameters, and the value of H_0
dc.typetext

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