Solar abundance of manganese: a case for near Chandrasekhar-mass Type Ia supernova progenitors

¹ Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Campus Hubland Nord, Emil-Fischer-Str. 31, 97074 Würzburg, Germany
e-mail: iseitenzahl@astro.uni-wuerzburg.de
² Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
³ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁴ Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany

Received: 3 September 2013
Accepted: 1 October 2013

Abstract

Context. Manganese is predominantly synthesised in Type Ia supernova (SN Ia) explosions. Owing to the entropy dependence of the Mn yield in explosive thermonuclear burning, SNe Ia involving near Chandrasekhar-mass (M_Ch) white dwarfs (WDs) are predicted to produce Mn-to-Fe ratios that significantly exceed those of SN Ia explosions involving sub-Chandrasekhar mass primary WDs. Of all current supernova explosion models, only SN Ia models involving near-M_Ch WDs produce [Mn/Fe] ≳ 0.0.

Aims. Using the specific yields for competing SN Ia scenarios, we aim to constrain the relative fractions of exploding near-M_Ch to sub-M_Ch primary WDs in the Galaxy.

Methods. We extract the Mn yields from three-dimensional thermonuclear supernova simulations that refer to different initial setups and progenitor channels. We then compute the chemical evolution of Mn in the solar neighborhood, assuming SNe Ia are made up of different relative fractions of the considered explosion models.

Results. We find that due to the entropy dependence of freeze-out yields from nuclear statistical equilibrium, [Mn/Fe] depends strongly on the mass of the exploding WD, with near-M_Ch WDs producing substantially higher [Mn/Fe] than sub-M_Ch WDs. Of all nucleosynthetic sources potentially influencing the chemical evolution of Mn, only explosion models involving the thermonuclear incineration of near-M_Ch WDs predict solar or super-solar [Mn/Fe]. Consequently, we find in our chemical evolution calculations that the observed [Mn/Fe] in the solar neighborhood at [Fe/H] ≳ 0.0 cannot be reproduced without near-M_Ch SN Ia primaries. Assuming that 50% of all SNe Ia stem from explosive thermonuclear burning in near-M_Ch WDs results in a good match to data.