Type Ia supernovae in the star formation deserts of spiral host galaxies

Using a sample of nearby spiral galaxies hosting 185 supernovae (SNe) Ia, we perform a comparative analysis of the locations and light curve decline rates $(\Delta m_{15})$ of normal and peculiar SNe Ia in the star formation deserts (SFDs) and beyond. To accomplish this, we present a simple visual classification approach based on the UV/H$\alpha$ images of the discs of host galaxies. We demonstrate that, from the perspective of the dynamical timescale of the SFD, where the star formation (SF) is suppressed by the bar evolution, the $\Delta m_{15}$ of SN Ia and progenitor age can be related. The SFD phenomenon gives an excellent possibility to separate a subpopulation of SN Ia progenitors with the ages older than a few Gyr. We show, for the first time, that the SFDs contain mostly faster declining SNe Ia $(\Delta m_{15} > 1.25)$. For the galaxies without SFDs, the region within the bar radius, and outer disc contain mostly slower declining SNe Ia. To better constrain the delay times of SNe Ia, we encourage new studies (e.g. integral field observations) using the SFD phenomenon on larger and more robust datasets of SNe Ia and their host galaxies.

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