scholarly journals Common envelope episodes that lead to double neutron star formation

2020 ◽  
Vol 37 ◽  
Author(s):  
Alejandro Vigna-Gómez ◽  
Morgan MacLeod ◽  
Coenraad J. Neijssel ◽  
Floor S. Broekgaarden ◽  
Stephen Justham ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Large Fraction ◽  
Computational Modelling ◽  
Evolutionary Stage ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Common Envelope ◽  
The Common ◽  
The Moment

Abstract Close double neutron stars (DNSs) have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational wave sources. They are believed to have experienced at least one common envelope episode (CEE) during their evolution prior to DNS formation. In the last decades, there have been numerous efforts to understand the details of the common envelope (CE) phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche lobe overflow (RLOF) leading to these CEEs as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the CE phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the RLOF: giant donors with fully convective envelopes, cool donors with partially convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of RLOF. This makes the study and understanding of eccentric mass-transferring systems relevant for DNS populations.

scholarly journals The demographics of neutron star – white dwarf mergers

2018 ◽  
Vol 619 ◽  
pp. A53 ◽  
Author(s):  
S. Toonen ◽  
H. B. Perets ◽  
A. P. Igoshev ◽  
E. Michaely ◽  
Y. Zenati
Keyword(s):  
Delay Time ◽  
Time Distribution ◽  
Initial Conditions ◽  
Population Synthesis ◽  
Physical Processes ◽  
Common Envelope ◽  
Tail Distribution ◽  
Wide Range ◽  
Type Ia ◽  
Ia Supernovae

Context. The mergers of neutron stars (NSs) and white dwarfs (WDs) could give rise to explosive transients, potentially observable with current and future transient surveys. However, the expected properties and distribution of such events is not well understood. Aims. Here we characterise the rates of such events, their delay-time distributions, their progenitors, and the distribution of their properties. Methods. We use binary population synthesis models and consider a wide range of initial conditions and physical processes. In particular we consider different common-envelope evolution models and different NS natal kick distributions. We provide detailed predictions arising from each of the models considered. Results. We find that the majority of NS–WD mergers are born in systems in which mass-transfer played an important role, and the WD formed before the NS. For the majority of the mergers the WDs have a carbon-oxygen composition (60−80%) and most of the rest are with oxygen-neon WDs. The time-integrated rates of NS–WD mergers are in the range of 3−15% of the type Ia supernovae (SNe) rate. Their delay-time distribution is very similar to that of type Ia SNe, but is slightly biased towards earlier times. They typically explode in young 100 Myr < τ < 1 Gyr environments, but have a tail distribution extending to long, gigayear-timescales. Models including significant kicks give rise to relatively wide offset distribution extending to hundreds of kiloparsecs. Conclusions. The demographic and physical properties of NS–WD mergers suggest they are likely to be peculiar type Ic-like SNe, mostly exploding in late-type galaxies. Their overall properties could be related to a class of recently observed rapidly evolving SNe, while they are less likely to be related to the class of Ca-rich SNe.

scholarly journals The origin of spin in binary black holes

2020 ◽  
Vol 635 ◽  
pp. A97 ◽  
Author(s):  
Simone S. Bavera ◽  
Tassos Fragos ◽  
Ying Qin ◽  
Emmanouil Zapartas ◽  
Coenraad J. Neijssel ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Scientific Progress ◽  
Hybrid Technique ◽  
Population Synthesis ◽  
Binary Black Holes ◽  
Common Envelope ◽  
The Common ◽  
Binary Evolution

Context. After years of scientific progress, the origin of stellar binary black holes is still a great mystery. Several formation channels for merging black holes have been proposed in the literature. As more merger detections are expected with future gravitational-wave observations, population synthesis studies can help to distinguish between them. Aims. We study the formation of coalescing binary black holes via the evolution of isolated field binaries that go through the common envelope phase in order to obtain the combined distributions of observables such as black-hole spins, masses and cosmological redshifts of mergers. Methods. To achieve this aim, we used a hybrid technique that combines the parametric binary population synthesis code COMPAS with detailed binary evolution simulations performed with the MESA code. We then convolved our binary evolution calculations with the redshift- and metallicity-dependent star-formation rate and the selection effects of gravitational-wave detectors to obtain predictions of observable properties. Results. By assuming efficient angular momentum transport, we are able to present a model that is capable of simultaneously predicting the following three main gravitational-wave observables: the effective inspiral spin parameter χeff, the chirp mass Mchirp and the cosmological redshift of merger zmerger. We find an excellent agreement between our model and the ten events from the first two advanced detector observing runs. We make predictions for the third observing run O3 and for Advanced LIGO design sensitivity. We expect approximately 80% of events with χeff <  0.1, while the remaining 20% of events with χeff ≥ 0.1 are split into ∼10% with Mchirp <  15 M⊙ and ∼10% with Mchirp ≥ 15 M⊙. Moreover, we find that Mchirp and χeff distributions are very weakly dependent on the detector sensitivity. Conclusions. The favorable comparison of the existing LIGO/Virgo observations with our model predictions gives support to the idea that the majority, if not all of the observed mergers, originate from the evolution of isolated binaries. The first-born black hole has negligible spin because it lost its envelope after it expanded to become a giant star, while the spin of the second-born black hole is determined by the tidal spin up of its naked helium star progenitor by the first-born black hole companion after the binary finished the common-envelope phase.

scholarly journals Binary population synthesis with probabilistic remnant mass and kick prescriptions

2020 ◽  
Vol 500 (1) ◽  
pp. 1380-1384
Author(s):  
Ilya Mandel ◽  
Bernhard Müller ◽  
Jeff Riley ◽  
Selma E de Mink ◽  
Alejandro Vigna-Gómez ◽  
...  
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Population Synthesis ◽  
Common Envelope ◽  
Low Mass ◽  
The Common ◽  
The Masses ◽  
The Impact ◽  
Hertzsprung Gap ◽  
Remnant Mass

ABSTRACT We report on the impact of a probabilistic prescription for compact remnant masses and kicks on massive binary population synthesis. We find that this prescription populates the putative mass gap between neutron stars and black holes with low-mass black holes. However, evolutionary effects reduce the number of X-ray binary candidates with low-mass black holes, consistent with the dearth of such systems in the observed sample. We further find that this prescription is consistent with the formation of heavier binary neutron stars such as GW190425, but overpredicts the masses of Galactic double neutron stars. The revised natal kicks, particularly increased ultra-stripped supernova kicks, do not directly explain the observed Galactic double neutron star orbital period–eccentricity distribution. Finally, this prescription allows for the formation of systems similar to the recently discovered extreme mass ratio binary GW190814, but only if we allow for the survival of binaries in which the common envelope is initiated by a donor crossing the Hertzsprung gap, contrary to our standard model.

scholarly journals Pulsar Velocities

1996 ◽  
Vol 165 ◽  
pp. 213-223
Author(s):  
Matthew Bailes
Keyword(s):  
Neutron Star ◽  
Large Fraction ◽  
Selection Effects ◽  
Proper Motions ◽  
Simple Argument ◽  
Common Envelope ◽  
Upper Limit ◽  
The Galaxy ◽  
The Common ◽  
Binary Evolution

Lyne & Lorimer (1994) recently demonstrated that revisions to the pulsar distance scale, coupled with new interferometric measurements of pulsar proper motions and a better treatment of selection effects, indicate that typical pulsar velocities are of the order 450 km s−1. This is between a factor of 2–4 greater than most estimates made over the last decade. This paper looks at the implications of these higher velocities for the various theories about their origin. An extremely simple argument is used to place a fairly rigid upper limit for the rate at which neutron star pairs merge of 10−5 yr−1 in the Galaxy. It appears inevitable that an extremely large fraction of binaries containing neutron stars coalesce during the common-envelope stage of massive binary evolution.

scholarly journals Substellar Secondaries in Zero-Age Cataclysmic Variables

2004 ◽  
Vol 194 ◽  
pp. 89-91
Author(s):  
M. Politano
Keyword(s):  
Orbital Period ◽  
Formation Rate ◽  
Cataclysmic Variables ◽  
Population Synthesis ◽  
Mass Ratio ◽  
Brown Dwarf ◽  
Common Envelope ◽  
Efficiency Parameter ◽  
The Common ◽  
Orbital Periods

AbstractThe present-day formation of cataclysmic variables (CVs) with brown dwarf (BD) secondaries is investigated using a population synthesis technique. Results from the latest, detailed models for BDs have been incorporated into the population synthesis code. We find that zero-age CVs (ZACVs) with BD secondaries have orbital periods in the range 46 min to 2.5 hrs, and that they comprise 18% of the total, present-day ZACV population. Consequently, we find that 15% of the present-day ZACV population should have orbital periods shorter than the observed orbital period minimum for CVs. We also investigate the dependence of the present-day formation rate of CVs with BD secondaries on the assumed value of the common envelope efficiency parameter, αCE, for three different assumed mass ratio distributions in ZAMS binaries. We find that the common envelope process must be extremely inefficient (αCE < 0.1) in order for CVs with BD secondaries not to be formed. Finally, we find that the progenitor binaries of ZACVs with BD secondaries have ZAMS orbital separations < 3 AU and ZAMS primary masses between ~1-10 M⊙ , with ~75% of the primary masses less than ~ 1.6 M⊙. Interestingly, these ranges in orbital separation and primary mass place the majority of the progenitor binaries within the so-called “brown dwarf desert.”

scholarly journals Type Ia Supernovae and the Uncertainties in their Progenitor Evolution

2011 ◽  
Vol 7 (S281) ◽  
pp. 236-239
Author(s):  
J. S. W. Claeys ◽  
O. R. Pols ◽  
R. G. Izzard
Keyword(s):  
Type Ia Supernovae ◽  
Population Synthesis ◽  
Common Envelope ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae

AbstractWe use binary population synthesis to study the main proposed channels leading to Type Ia supernovae, the single degenerate channel (SD) and double degenerate channel (DD). For this purpose, we discuss the progenitor evolution and the influence of the common envelope efficiency, αce, on the rate of the different channels. Our study demonstrates the large αce-dependence of both channels, especially for the SD channel.

A New Image Encryption Scheme Using Dual Chaotic Map Synchronization

2020 ◽  
Vol 18 (1) ◽  
Keyword(s):  
Image Encryption ◽  
Chaotic Systems ◽  
Initial Conditions ◽  
Chaotic Map ◽  
Security Applications ◽  
The Common ◽  
And Diffusion ◽  
Confusion And Diffusion ◽  
Sensitivity To Initial Conditions ◽  
Diffusion Properties

Chaotic systems behavior attracts many researchers in the field of image encryption. The major advantage of using chaos as the basis for developing a crypto-system is due to its sensitivity to initial conditions and parameter tunning as well as the random-like behavior which resembles the main ingredients of a good cipher namely the confusion and diffusion properties. In this article, we present a new scheme based on the synchronization of dual chaotic systems namely Lorenz and Chen chaotic systems and prove that those chaotic maps can be completely synchronized with other under suitable conditions and specific parameters that make a new addition to the chaotic based encryption systems. This addition provides a master-slave configuration that is utilized to construct the proposed dual synchronized chaos-based cipher scheme. The common security analyses are performed to validate the effectiveness of the proposed scheme. Based on all experiments and analyses, we can conclude that this scheme is secure, efficient, robust, reliable, and can be directly applied successfully for many practical security applications in insecure network channels such as the Internet

scholarly journals Are extreme asymptotic giant branch stars post-common envelope binaries?

2021 ◽  
Vol 502 (1) ◽  
pp. L35-L39
Author(s):  
F Dell’Agli ◽  
E Marini ◽  
F D’Antona ◽  
P Ventura ◽  
M A T Groenewegen ◽  
...  
Keyword(s):  
Large Fraction ◽  
Carbon Star ◽  
Large Magellanic Cloud ◽  
Asymptotic Giant Branch ◽  
Theoretical Modelling ◽  
Binary Interaction ◽  
Spectral Energy ◽  
Small Subset ◽  
Stellar Radius ◽  
Common Envelope

ABSTRACT Modelling dust formation in single stars evolving through the carbon-star stage of the asymptotic giant branch (AGB) reproduces well the mid-infrared colours and magnitudes of most of the C-rich sources in the Large Magellanic Cloud (LMC), apart from a small subset of extremely red objects (EROs). An analysis of the spectral energy distributions of EROs suggests the presence of large quantities of dust, which demand gas densities in the outflow significantly higher than expected from theoretical modelling. We propose that binary interaction mechanisms that involve common envelope (CE) evolution could be a possible explanation for these peculiar stars; the CE phase is favoured by the rapid growth of the stellar radius occurring after C/O overcomes unity. Our modelling of the dust provides results consistent with the observations for mass-loss rates $\dot{M} \sim 5\times 10^{-4}\,{\rm M}_{\odot }$ yr−1, a lower limit to the rapid loss of the envelope experienced in the CE phase. We propose that EROs could possibly hide binaries with orbital periods of about days and are likely to be responsible for a large fraction of the dust production rate in galaxies.

scholarly journals Metallicity effect and planet mass function in pebble-based planet formation models

2018 ◽  
Vol 619 ◽  
pp. A174 ◽  
Author(s):  
N. Brügger ◽  
Y. Alibert ◽  
S. Ataiee ◽  
W. Benz
Keyword(s):  
Internal Structure ◽  
Planet Formation ◽  
Large Fraction ◽  
Mass Function ◽  
Planetary Atmosphere ◽  
Population Synthesis ◽  
Core Accretion ◽  
Mass Functions ◽  
Synthesis Approach ◽  
Gaseous Envelope

Context. One of the main scenarios of planet formation is the core accretion model where a massive core forms first and then accretes a gaseous envelope. This core forms by accreting solids, either planetesimals or pebbles. A key constraint in this model is that the accretion of gas must proceed before the dissipation of the gas disc. Classical planetesimal accretion scenarios predict that the time needed to form a giant planet’s core is much longer than the time needed to dissipate the disc. This difficulty led to the development of another accretion scenario, in which cores grow by accretion of pebbles, which are much smaller and thus more easily accreted, leading to more rapid formation. Aims. The aim of this paper is to compare our updated pebble-based planet formation model with observations, in particular the well-studied metallicity effect. Methods. We adopt the Bitsch et al. (2015a, A&A, 575, A28) disc model and the Bitsch et al. (2015b, A&A, 582, A112) pebble model and use a population synthesis approach to compare the formed planets with observations. Results. We find that keeping the same parameters as in Bitsch et al. (2015b, A&A, 582, A112) leads to no planet growth due to a computation mistake in the pebble flux (2018b). Indeed a large fraction of the heavy elements should be put into pebbles (Zpeb∕Ztot = 0.9) in order to form massive planets using this approach. The resulting mass functions show a huge amount of giants and a lack of Neptune-mass planets, which are abundant according to observations. To overcome this issue we include the computation of the internal structure for the planetary atmosphere in our model. This leads to the formation of Neptune-mass planets but no observable giants. Furthermore, reducing the opacity of the planetary envelope more closely matches observations. Conclusions. We conclude that modelling the internal structure for the planetary atmosphere is necessary to reproduce observations.

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