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Determination of the rates at which supernovae of Type Ia (SNe Ia) occur in the early Universe can give signatures of the time spent by the binary progenitor systems to reach explosion and of the geometry of the Universe. Observations made…
The progenitors of Type Ia supernovae (SNe Ia) are debated, particularly the evolutionary state of the binary companion that donates mass to the exploding carbon-oxygen white dwarf. In previous work, we presented hydrodynamic models and…
We consider a binary stellar system, in which a low-mass, of 0.6 Msun, carbon-oxygen white dwarf (WD) mergers with a degenerate helium core of 0.4 Msun of a red giant. We analyse the outcome of a merger within a common envelope (CE). We…
We describe our ongoing program designed to measure the SN-Ia rate in a sample of massive z=0.5-0.9 galaxy clusters. The SN-Ia rate is a poorly known observable, especially at high z, and in cluster environments. The SN rate and its…
The nebular-epoch spectrum of the rapidly declining, "transitional" type Ia supernova (SN) 2007on showed double emission peaks, which have been interpreted as indicating that the SN was the result of the direct collision of two white…
Observations of Type Ia supernovae (SN~Ia) combined with modeling of dynamics, light curves and spectra continue to point to the difficult conclusion that SN~Ia result from degenerate ignition in a carbon/oxygen white dwarf of the…
Type Ia supernovae (SNe) are believed to be caused by the thermonuclear explosion of a white dwarf (WD), but the nature of the progenitor system(s) is still unclear. Recent theoretical and observational developments have led to renewed…
We present and discuss the radio observations of 27 Type Ia supernovae (SNe Ia) observed over two decades with the Very Large Array. No SN Ia has been detected so far in the radio, implying a very low density for any possible circumstellar…
We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee in NGC~2708 ($D = 32 \pm 3$ Mpc), finding excess flux in the first days after explosion relative to the expected power-law rise…
We use the redshift distribution of type-Ia supernovae (SNe) discovered by the Supernova Cosmology Project to constrain the star formation history (SFH) of the Universe and SN Ia progenitor models. Given some of the recent determinations of…
There is a consensus that Type-Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise…
In the SD scenario of SNe Ia the companion survives the SN explosion and thus should be visible near the center of the SN remnant and may show some unusual features. A promising approach to test progenitor models of SNe Ia is to search for…
All types of supernovae (SNe), except Type Ia, have been observed to interact with their immediate circumstellar medium (CSM). This interaction can reveal their progenitor's histories, and constrain our ideas about the evolution of massive…
In the symbiotic (or WD+RG) channel of the single degenerate scenario for type Ia supernovae (SNe Ia) the explosions occur a relatively long time after star formation. The birthrate from this channel would be too low to account for all…
We investigate the contribution of different formation scenarios for type Ia supernovae in elliptical galaxies. The single degenerate scenario (a white dwarf accreting from a late main sequence or red giant companion) is tested against the…
Several explosions of thermonuclear supernovae (SNe Ia) have been found to exhibit deviations from spherical symmetry upon closer inspection. Examples are the gamma-ray lines from SN 2014J as measured by INTEGRAL/SPI, and morphology…
Type Ia supernovae (SNe Ia) are among the most precise cosmological distance indicators used to study the expansion history of the Universe. The vast increase of SN Ia data due to large-scale astrophysical surveys has led to the discovery…
Recent studies indicate that Type Ia supernovae (SNe Ia) consist of two groups - a "prompt" component whose rates are proportional to the host galaxy star formation rate, whose members have broader lightcurves and are intrinsically more…
SN 2002cx-like Type Ia supernovae (also known as SNe Iax) represent one of the most numerous peculiar SN classes. They differ from normal SNe Ia by having fainter peak magnitudes, faster decline rates and lower photospheric velocities,…
The present cosmic rate of Type Ia supernovae (SNeIa) suggests that about 6% of all stars in binary systems with primaries in the initial mass range $3-9\ M\sun$ end up as SNeIa. If that is confirmed, the unavoidable conclusion is that…