Dynamic mass exchange in doubly degenerate binaries. I - 0.9 and 1.2 solar mass stars

Benz, W.; Bowers, R.L.; Cameron, A. G. W.; Press, William H.

doi:10.1086/168273

Cited by 428 publications

(422 citation statements)

References 0 publications

Supporting

Mentioning

411

Contrasting

Order By: Relevance

“…Merger of two WDs (Iben & Tutukov 1984;Webbink 1984;Benz et al 1990;Pakmor et al 2010Pakmor et al , 2011 has recently drawn attention because of perceived advantages for solving the Type Ia progenitor problem (Ruiter et al 2009;Schaefer & Pagnotta al. 2012).…”

Section: Sub-chandrasekhar Mass Explosions and Mergersmentioning

confidence: 99%

VLT Spectropolarimetry of the Type Ia SN 2005ke

Patat¹,

Hoêflich²,

Baade³

et al. 2012

A&A

View full text Add to dashboard Cite

Aims. In this study we try to answer the question whether or not subluminous Type Ia supernovae have additional distinctive properties when examined from the point of view of the explosion geometry. Methods. We have performed optical spectropolarimetric observations of the Type Ia SN 2005ke at 3 epochs (days −8, −7, and +76). The explosion properties are derived by comparing the data to explosion and radiation transfer models. Results. The supernova shows polarimetric properties that are very similar to the only other subluminous event for which spectropolarimetry is available, i.e. SN 1999by. The data present a very marked dominant axis, which is shared by both the continuum and lines such as Si ii λ6355, suggesting that the relatively large, global asymmetry is common to the photosphere and the line-forming region. The maximum polarization degree observed in the Si ii λ6355 absorption reaches 0.39 ± 0.08%. At variance with what is seen in core-normal Type Ia, SN 2005ke displays significant continuum polarization, which grows from the blue to the red and peaks at about 7000 Å, reaching ∼0.7%. The properties of the polarization and flux spectra can be understood within the framework of a subluminous delayed-detonation (DD), or pulsating DD scenario, or white dwarf (WD) mergers. The difference in appearance with respect to core-normal SNe Ia is caused by low photospheric temperatures in combination with layers of unburned C, and more massive layers of the products of explosive C and O burning. The comparatively high level of continuum polarization is explained in terms of a significant global asymmetry (∼15%), which is well reproduced by an oblate ellipsoidal geometry within the general context of a DD explosion. Conclusions. Our results suggest that SN 2005ke arose either from a single-degenerate system in which the WD is especially rapidly rotating, close to the break-up velocity, or from a double-degenerate merger. Based on the current polarization data, we cannot distinguish between these two possibilities. Possible tests are discussed.

show abstract

Section: Sub-chandrasekhar Mass Explosions and Mergersmentioning

confidence: 99%

VLT Spectropolarimetry of the Type Ia SN 2005ke

Patat¹,

Hoêflich²,

Baade³

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…Hillebrandt & Niemeyer 2000). Benz et al (1990) found that in a binary system of a 1.2 M and a 0.9 M white dwarf the less massive white dwarf is disrupted and accreted onto the more massive white dwarf. This happens within a few orbits after mass transfer between the stars has started.…”

Section: Introductionmentioning

confidence: 99%

Violent mergers of nearly equal-mass white dwarf as progenitors of subluminous Type Ia supernovae

Pakmor

Hachinger

Röpke

et al. 2011

A&A

207

265

View full text Add to dashboard Cite

Context. The origin of subluminous Type Ia supernovae (SNe Ia) has long eluded any explanation, because all Chandrasekhar-mass models have severe problems reproducing them. Recently, it has been proposed that violent mergers of two white dwarfs of 0.9 M could lead to subluminous SNe Ia events that resemble 1991bg-like SNe Ia. Aims. Here we investigate whether this scenario still works for mergers of two white dwarfs with a mass ratio below one. We aim to determine the range of mass ratios for which a detonation still forms during the merger, as only those events will lead to an SN Ia. This range is an important ingredient for population synthesis and one decisive point for judging the viability of the scenario. In addition, we perform a resolution study of one of the models. Finally we discuss the connection between violent white dwarf mergers with a primary mass of 0.9 M and 1991bg-like SNe Ia. Methods. The latest version of the smoothed particle hydrodynamics code Gadget3 was used to evolve binary systems with different mass ratios until they merge. We analyzed the result and looked for hot spots in which detonations can form. Results. We show that mergers of two white dwarfs with a primary white dwarf mass of ≈0.9 M and a mass ratio more than about 0.8 robustly reach the conditions we require for igniting a detonation and thus produce thermonuclear explosions during the merger itself. We also find that, while our simulations do not yet completely resolve the hot spots, increasing the resolution leads to conditions that are even more likely to ignite detonations. Additionally, we compare the abundance structure of the ejecta of the thermonuclear explosion of two merged white dwarfs with data inferred from observations of a 1991bg-like SN Ia (SN 2005bl). The abundance distributions of intermediate mass and iron group elements in velocity space agree qualitatively, and our model reproduces the lack of material at high velocities inferred from the observations. Conclusions. The violent merger scenario constitutes a robust possibility for two merging white dwarfs to produce a thermonuclear explosion. Mergers with a primary white dwarf mass of ≈0.9 M are very promising candidates for explaining subluminous SNe Ia. This would imply that subluminous SNe Ia form a distinct class of objects, which are not produced in the standard single white dwarf scenario for SNe Ia, but instead arise from a different progenitor channel and explosion mechanism.

show abstract

“…In what follows, we will describe the implementation of MODA into a recently developed recursive coordinate bisection (RCB) tree (Gafton & Rosswog 2011). The implementation strategy, however, is not restricted to this type of tree and can straightforwardly be adapted to other tree types such as octree (Barnes & Hut 1986) or other binary trees (Benz et al 1990). The RCB tree is not built down to the last particle, but down to small groups of adjacent particles that are always aggregated into what we call "lowest-level cells" (or ll-cells), also found in the "tree literature" as "leaves" (Oxley & Woolfson 2003;Springel 2005;Gaburov et al 2010;Hubber et al 2011;Clark et al 2012) or as "buckets" (Dikaiakos & Stadel 1996;Stadel 2001;Wadsley et al 2004).…”

Section: Performing the Integrationmentioning

confidence: 99%

MODA: a new algorithm to compute optical depths in multidimensional hydrodynamic simulations

Perego

Gafton

Cabezón

et al. 2014

A&A

View full text Add to dashboard Cite

Aims. We introduce the multidimensional optical depth algorithm (MODA) for the calculation of optical depths in approximate multidimensional radiative transport schemes, equally applicable to neutrinos and photons. Motivated by (but not limited to) neutrino transport in three-dimensional simulations of core-collapse supernovae and neutron star mergers, our method makes no assumptions about the geometry of the matter distribution, apart from expecting optically transparent boundaries. Methods. Based on local information about opacities, the algorithm figures out an escape route that tends to minimize the optical depth without assuming any predefined paths for radiation. Its adaptivity makes it suitable for a variety of astrophysical settings with complicated geometry (e.g., core-collapse supernovae, compact binary mergers, tidal disruptions, star formation, etc.). We implement the MODA algorithm into both a Eulerian hydrodynamics code with a fixed, uniform grid and into an SPH code where we use a tree structure that is otherwise used for searching neighbors and calculating gravity. Results. In a series of numerical experiments, we compare the MODA results with analytically known solutions. We also use snapshots from actual 3D simulations and compare the results of MODA with those obtained with other methods, such as the global and local ray-by-ray method. It turns out that MODA achieves excellent accuracy at a moderate computational cost. In appendix we also discuss implementation details and parallelization strategies.

show abstract

Dynamic mass exchange in doubly degenerate binaries. I - 0.9 and 1.2 solar mass stars

Cited by 428 publications

References 0 publications

VLT Spectropolarimetry of the Type Ia SN 2005ke

VLT Spectropolarimetry of the Type Ia SN 2005ke

Violent mergers of nearly equal-mass white dwarf as progenitors of subluminous Type Ia supernovae

MODA: a new algorithm to compute optical depths in multidimensional hydrodynamic simulations

Contact Info

Product

Resources

About