The supernova rate per unit mass

¹ CNR – IRA, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: filippo@arcetri.astro.it
² INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁴ INAF, Osservatorio Astronomico di Capodimonte, salita Moiariello a Capodimonte 16, 80131 Napoli, Italy
⁵ Dipartimento di Astronomia, Universitá di Firenze, Largo E. Fermi 5, 50125, Firenze, Italy
⁶ Byurakan Astrophysical Observatory and Isaac Newton Institute of Chile, Armenian Branch, Byurakan 378433, Armenia
⁷ INAF, Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy

Received: 4 June 2004
Accepted: 17 November 2004

Abstract

We compute the rate of supernovae (SNe) of different types along the Hubble sequence normalized to the near-infrared luminosity and to the stellar mass of the parent galaxies. This is made possible by the new complete catalog of near-infrared galaxy magnitudes obtained by 2MASS. We find that the rates of all SN types, including Ia, Ib/c and II, show a sharp dependence on both the morphology and the () colors of the parent galaxies and, therefore, on the star formation activity. In particular we find, with a high statistical significance, that the type Ia rate in late type galaxies is a factor ~20 higher than in E/S0. Similarly, the type Ia rate in the galaxies bluer than is about a factor of 30 larger than in galaxies with . These findings can be explained by assuming that a significant fraction of Ia events in late spirals/irregulars originates in a relatively young stellar component.