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4 Publications visible to you, out of a total of 4
Faint calcium-rich transient from a double detonation of a 0.6 M⊙ carbon-oxygen white dwarf star

Abstract (Expand)

We have computed a three-dimensional hydrodynamic simulation of the merger between a massive (0.4 M_⊙) helium white dwarf (He WD) and a low-mass (0.6 M_⊙) carbon-oxygen white dwarf (CO WD). Despite the … low mass of the primary, the merger triggers a thermonuclear explosion as a result of a double detonation, producing a faint transient and leaving no remnant behind. This type of event could also take place during common-envelope mergers whenever the companion is a CO WD and the core of the giant star has a sufficiently large He mass. The spectra show strong Ca lines throughout the first few weeks after the explosion. The explosion only yields <0.01 M_⊙of ^56Ni, resulting in a low-luminosity SN Ia-like lightcurve that resembles the Ca-rich transients within this broad class of objects, with a peak magnitude of M_\mathrmbol ≈-15.7 mag and a rather slow decline rate of ∆m_15^\mathrmbol≈1.5 mag. Both, its lightcurve-shape and spectral appearance, resemble the appearance of Ca-rich transients, suggesting such mergers as a possible progenitor scenario for this class of events.

Authors: Javier Morán-Fraile, Alexander Holas, Friedrich K Röpke, Rüdiger Pakmor, Fabian R N Schneider

Date Published: 4th Mar 2024

Publication Type: Journal

Self-consistent magnetohydrodynamic simulation of jet launching in a neutron star – white dwarf merger

Abstract (Expand)

The merger of a white dwarf (WD) and a neutron star (NS) is a relatively common event that will produce an observable electromagnetic signal. Furthermore, the compactness of these stellar objects makes … them an interesting candidate for gravitational wave (GW) astronomy, potentially being in the frequency range of LISA and other missions. To date, three-dimensional simulations of these mergers have not fully modelled the WD disruption, or have used lower resolutions and have not included magnetic fields even though they potentially shape the evolution of the merger remnant. In this work, we simulate the merger of a 1.4M_⊙NS with a 1M_⊙carbon oxygen WD in the magnetohydrodynamic moving mesh code \AREPO. We find that the disruption of the WD forms an accretion disk around the NS, and the subsequent accretion by the NS powers the launch of strongly magnetized, mildly relativistic jets perpendicular to the orbital plane. Although the exact properties of the jets could be altered by unresolved physics around the NS, the event could result in a transient with a larger luminosity than kilonovae. We discuss possible connections to fast blue optical transients (FBOTs) and long-duration gamma-ray bursts. We find that the frequency of GWs released during the merger is too high to be detectable by the LISA mission, but suitable for deci-hertz observatories such as LGWA, BBO or DECIGO.

Authors: J. Moran-Fraile, F. K. Roepke, R. Pakmor, M. A. Aloy, S. T. Ohlmann, F. R. N. Schneider, G. Leidi

Date Published: 5th Jan 2024

Publication Type: Journal

Gravitational wave emission from dynamical stellar interactions

Abstract

Not specified

Authors: J. Moran-Fraile, F. Schneider, F. Roepke, S. Ohlmann, R. Pakmor, T. Soultanis, A. Bauswein

Date Published: 27th Feb 2023

Publication Type: Journal

Polluting the Pair-instability Mass Gap for Binary Black Holes through Super-Eddington Accretion in Isolated Binaries

Abstract (Expand)

The theory for single stellar evolution predicts a gap in the mass distribution of black holes (BHs) between approximately 45 and 130 $\,{M}_{\odot }$, the so-called "pair-instability mass gap." … We examine whether BHs can pollute the gap after accreting from a stellar companion. To this end, we simulate the evolution of isolated binaries using a population synthesis code, where we allow for super-Eddington accretion. Under our most extreme assumptions, we find that at most about 2% of all merging binary BH systems contains a BH with a mass in the pair-instability mass gap, and we find that less than 0.5% of the merging systems has a total mass larger than 90 $\,{M}_{\odot }$. We find no merging binary BH systems with a total mass exceeding 100 $\,{M}_{\odot }$. We compare our results to predictions from several dynamical pathways to pair-instability mass gap events and discuss the distinguishable features. We conclude that the classical isolated binary formation scenario will not significantly contribute to the pollution of the pair-instability mass gap. The robustness of the predicted mass gap for the isolated binary channel is promising for the prospective of placing constraints on (i) the relative contribution of different formation channels, (ii) the physics of the progenitors including nuclear reaction rates, and, tentatively, (iii) the Hubble parameter.

Authors: L. A. C. van Son, S. E. De Mink, F. S. Broekgaarden, M. Renzo, S. Justham, E. Laplace, J. Morán-Fraile, D. D. Hendriks, R. Farmer

Date Published: 1st Jul 2020

Publication Type: Journal

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