Related papers: Population synthesis for double white dwarfs I.Clo…
We present a new model for the Galactic population of close double white dwarfs. The model accounts for the suggestion of the avoidance of a substantial spiral-in during mass transfer between a giant and a main-sequence star of comparable…
We study two models for AM CVn stars: white dwarfs accreting (i) from a helium white dwarf companion and (ii) from a helium-star donor. We show that in the first model possibly no accretion disk forms at the onset of mass transfer. The…
We use multi-epoch spectroscopy of about 4000 white dwarfs in the Sloan Digital Sky Survey to constrain the properties of the Galactic population of binary white dwarf systems and calculate their merger rate. With a Monte Carlo code, we…
The $Gaia$ mission has provided an unprecedented wealth of information about the white dwarf population of our Galaxy. In particular, our studies show that the sample up to 100\,pc from the Sun can be considered as practically complete.…
Recent Hubble Space Telescope observations have unveiled the white dwarf cooling sequence of the Galactic bulge. Although the degenerate sequence can be well fitted employing the most up-to-date theoretical cooling sequences, observations…
Using a detailed Galactic model in which we consider distinct contributions from the bulge, thin disc, thick disc, and halo, and a population synthesis approach, we determined the birth rates, numbers, and period distributions of double…
We have carried out a detailed study of symbiotic stars with white dwarf accretors by means of a population synthesis code. We estimate the total number of symbiotic stars with white dwarf accretors in the Galaxy as 1,200 - 15,000. This…
Using population synthesis, we study a double-degenerate (DD) scenario for SNe Ia, aiming to estimate the maximum possible contribution to the rate of SNe from this scenario and the dependence of the delay-time distribution (DTD) on it. We…
We have considered scenarios for the evolution of close binaries resulting in the formation of semi-detached systems in which a white dwarf can accumulate Chandrasekhar mass by accretion from a main-sequence or subgiant companion with…
We obtain new and precise information on the double white dwarf (DWD) population and on its gravitational-wave-driven merger rate, by combining the constraints on the DWD population from two previous radial-velocity-variation studies: One…
The mergers of double helium white dwarfs are believed to form isolated helium-rich hot subdwarfs. Observation shows that the helium-rich hot subdwarfs can be divided into two subgroups based on whether the surface is carbon-rich or…
We estimate the merger rate of double degenerate binaries containing extremely low mass (ELM) <0.3 Msun white dwarfs in the Galaxy. Such white dwarfs are detectable for timescales of 0.1 Gyr -- 1 Gyr in the ELM Survey; the binaries they…
We present Chandra and Swift X-ray observations of four extremely low-mass (ELM) white dwarfs with massive companions. We place stringent limits on X-ray emission from all four systems, indicating that neutron star companions are extremely…
From a sample of spectra of 439 white dwarfs (WDs) from the ESO-VLT Supernova-Ia Progenitor surveY (SPY), we measure the maximal changes in radial-velocity (DRVmax) between epochs (generally two epochs, separated by up to 470d), and model…
Double white dwarf binaries are a leading explanation to the origin of type Ia supernovae, but no system exceeding the Chandrasekhar mass limit (1.4 M$_\odot$) has been found that will explode anywhere close to a Hubble time. Here, we…
Recent theoretical and observational studies both argue that the merging of double carbon-oxygen white dwarfs (WDs) is responsible for at least some Type Ia supernovae (SNe Ia). Previous (standard) studies of the anticipated SN birthrate…
In this paper we consider the population of eccentric binaries with a neutron star and a white dwarf that has been revealed in our galaxy in recent years through binary pulsar observations. We apply our statistical analysis method (Kim,…
Accreting, nuclear-burning white dwarfs have been deemed to be candidate progenitors of type Ia supernovae, and to account for supersoft X-ray sources, novae, etc. depending on their accretion rates. We have carried out a binary population…
We have extended our detailed survey of the local white dwarf population from 20 pc to 25 pc, effectively doubling the sample volume, which now includes 232 stars. In the process new stars within 20 pc have been added, a more uniform set of…
Double white dwarf binaries with merger timescales smaller than the Hubble time and with a total mass near the Chandrasekhar limit (i.e. classical Chandrasekhar population) or with high-mass primaries (i.e. sub-Chandrasekhar population) are…