scholarly journals Core-collapse supernovae in binaries as the origin of galactic hyper-runaway stars

2020 ◽  
Vol 497 (4) ◽  
pp. 5344-5363 ◽  
Author(s):  
F A Evans ◽  
M Renzo ◽  
E M Rossi
Keyword(s):  
Milky Way ◽  
Core Collapse ◽  
Population Synthesis ◽  
Common Envelope ◽  
Peculiar Velocities ◽  
Large Velocity ◽  
Binary Evolution ◽  
Black Hole Remnant ◽  
Escape Speed ◽  
Runaway Stars

ABSTRACT Several stars detected moving at velocities near to or exceeding the Galactic escape speed likely originated in the Milky Way disc. We quantitatively explore the ‘binary supernova scenario’ hypothesis, wherein these ‘hyper-runaway’ stars are ejected at large peculiar velocities when their close, massive binary companions undergo a core-collapse supernova and the binary is disrupted. We perform an extensive suite of binary population synthesis simulations evolving massive systems to determine the assumptions and parameters that most impact the ejection rate of fast stars. In a simulation tailored to eject fast stars, we find the most likely hyper-runaway star progenitor binary is composed of a massive (${\sim}30\, \mathrm{ M}_{\odot }$) primary and an ${\sim}3\!-\!4\, \mathrm{ M}_{\odot }$ companion on an orbital period that shrinks to ≲1 d prior to the core collapse following a common-envelope phase. The black hole remnant formed from the primary must receive a natal kick ≳1000 km s−1 to disrupt the binary and eject the companion at a large velocity. We compare the fast stars produced in these simulations to a contemporary census of early-type Milky Way hyper-runaway star candidates. We find that these rare objects may be produced in sufficient number only when poorly constrained binary evolution parameters related to the strength of post-core-collapse remnant natal kicks and common-envelope efficiency are adjusted to values currently unsupported – but not excluded – by the literature. We discuss observational implications that may constrain the existence of these putative progenitor systems.

scholarly journals Massive runaway and walkaway stars

2019 ◽  
Vol 624 ◽  
pp. A66 ◽  
Author(s):  
M. Renzo ◽  
E. Zapartas ◽  
S. E. de Mink ◽  
Y. Götberg ◽  
S. Justham ◽  
...  
Keyword(s):  
Binary Systems ◽  
Numerical Study ◽  
Core Collapse ◽  
Mass Distributions ◽  
Peculiar Velocities ◽  
Order Of Magnitude ◽  
Massive Binary Systems ◽  
Stringent Test ◽  
Binary Evolution ◽  
Runaway Stars

We perform an extensive numerical study of the evolution of massive binary systems to predict the peculiar velocities that stars obtain when their companion collapses and disrupts the system. Our aim is to (i) identify which predictions are robust against model uncertainties and assess their implications, (ii) investigate which physical processes leave a clear imprint and may therefore be constrained observationally, and (iii) provide a suite of publicly available model predictions to allow for the use of kinematic constraints from the Gaia mission. We find that 22+26−8% of all massive binary systems merge prior to the first core-collapse in the system. Of the remainder, 86+11−9% become unbound because of the core-collapse. Remarkably, this rarely produces runaway stars (observationally defined as stars with velocities above 30 km s−1). These are outnumbered by more than an order of magnitude by slower unbound companions, or “walkaway stars”. This is a robust outcome of our simulations and is due to the reversal of the mass ratio prior to the explosion and widening of the orbit, as we show analytically and numerically. For stars more massive than 15 M⊙, we estimate that 10+5−8% are walkaways and only 0.5+1.0−0.4% are runaways, nearly all of which have accreted mass from their companion. Our findings are consistent with earlier studies; however, the low runaway fraction we find is in tension with observed fractions of about 10%. Thus, astrometric data on presently single massive stars can potentially constrain the physics of massive binary evolution. Finally, we show that the high end of the mass distributions of runaway stars is very sensitive to the assumed black hole natal kicks, and we propose this as a potentially stringent test for the explosion mechanism. We also discuss companions remaining bound that can evolve into X-ray and gravitational wave sources.

scholarly journals Population Synthesis of Type Ia SNe: Constraining Free Parameters from Observations

2011 ◽  
Vol 7 (S281) ◽  
pp. 240-243
Author(s):  
Maxwell Moe ◽  
Rosanne Di Stefano
Keyword(s):  
Mass Transfer ◽  
First Principles ◽  
Type Ia Supernovae ◽  
Population Synthesis ◽  
Common Envelope ◽  
Tidal Interactions ◽  
Type Ia ◽  
Free Parameters ◽  
Binary Evolution ◽  
Ia Supernovae

AbstractComputing the rate of Type Ia supernovae (SNe Ia) from first principles is difficult because there are large uncertainties regarding several key binary processes such as common envelope evolution, tidal interactions, and the efficiency of mass transfer. Fortunately, a range of observational parameters of binaries in intermediate stages of evolution can help us model these processes in a way that is likely to mirror the true binary evolution. We discuss how this observationally-motivated approach may have the effect of increasing the predicted rate of single degenerate progenitors of SNe Ia, while simultaneously decreasing the number of double degenerate progenitors.

scholarly journals Masses of double neutron star mergers

2020 ◽  
Vol 639 ◽  
pp. A123 ◽  
Author(s):  
Matthias U. Kruckow
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Milky Way ◽  
Radio Pulsar ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Wave Observation ◽  
Binary Evolution ◽  
Star Binary

Aims. I aim to explain the mass discrepancy between the observed double neutron-star binary population by radio pulsar observations and gravitational-wave observation. Methods. I performed binary population synthesis calculations and compared their results with the radio and the gravitational-wave observations simultaneously. Results. Simulations of binary evolution were used to link different observations of double neutron star binaries with each other. I investigated the progenitor of GW190425 in more detail. A distribution of masses and merger times of the possible progenitors is presented. Conclusions. A mass discrepancy between the radio pulsars in the Milky Way with another neutron star companion and the inferred masses from gravitational-wave observations of those kind of merging systems is naturally found in binary evolution.

scholarly journals The impact of close binary evolution on the properties of the WR-bump emission lines of Wolf-Rayet galaxies

2003 ◽  
Vol 212 ◽  
pp. 576-577
Author(s):  
Joris Van Bever ◽  
Dany Vanbeveren
Keyword(s):  
Mass Transfer ◽  
Neutron Stars ◽  
Supernova Explosion ◽  
Emission Lines ◽  
Close Binary ◽  
Population Synthesis ◽  
Common Envelope ◽  
Solar Metallicity ◽  
Binary Evolution ◽  
The Impact

We present the results of a study on the behaviour of the blue and red WR emission bumps (around 4650Å and 5808Å) and of the nebular contribution to He ii λ4686 in evolving young starburst regions (such as Wolf-Rayet galaxies), containing a non-negligible binary population. Calculations were made for solar metallicity and 1/20 solar. The population synthesis program uses an extended library of stellar evolutionary tracks of single stars and binaries, computed using the most recent stellar wind mass loss rates during RSG, LBV and WR stages. In the case of binaries, we account in detail for the effects of Roche lobe overflow, mass transfer and mass accretion, common envelope evolution, the spiral-in process, asymmetric kicks to neutron stars as a result of their supernova explosion, etc. This research is part of a more extensive project to explore every possible impact of massive binaries on stellar populations.

Runaway companions of supernova remnants with Gaia

2017 ◽  
Vol 12 (S330) ◽  
pp. 321-322
Author(s):  
Douglas Boubert ◽  
Morgan Fraser ◽  
N. Wyn Evans
Keyword(s):  
Supernova Remnants ◽  
Massive Stars ◽  
Core Collapse ◽  
Be Star ◽  
Binary Evolution ◽  
Runaway Stars

AbstractIt is expected that most massive stars have companions and thus that some core-collapse supernovae should have a runaway companion. The precise astrometry and photometry provided by Gaia allows for the systematic discovery of these runaway companions. We combine a prior on the properties of runaway stars from binary evolution with data from TGAS and APASS to search for runaway stars within ten nearby supernova remnants. We strongly confirm the existing candidate HD 37424 in S147, propose the Be star BD+50 3188 to be associated with HB 21, and suggest tentative candidates for the Cygnus and Monoceros Loops.

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 The connection between merging double compact objects and the Ultraluminous X-ray Sources

2019 ◽  
Author(s):  
Samaresh Mondal ◽  
Krzysztof Belczyński ◽  
Grzegorz Wiktorowicz ◽  
Jean-Pierre Lasota ◽  
Andrew R King
Keyword(s):  
Dynamical Evolution ◽  
Compact Objects ◽  
Population Synthesis ◽  
Local Universe ◽  
X Ray ◽  
Common Envelope ◽  
Envelope Model ◽  
Rate Calculation ◽  
Binary Evolution ◽  
Merger Rate

Abstract We explore the different formation channels of merging double compact objects (DCOs: BH-BH/BH-NS/NS-NS) that went through a ultraluminous X-ray phase (ULX: X-ray sources with apparent luminosity exceeding $10^{39}\rm {\ erg\ s^{-1}}$). There are many evolutionary scenarios which can naturally explain the formation of merging DCO systems: isolated binary evolution, dynamical evolution inside dense clusters and chemically homogeneous evolution of field binaries. It is not clear which scenario is responsible for the majority of LIGO/Virgo sources. Finding connections between ULXs and DCOs can potentially point to the origin of merging DCOs as more and more ULXs are discovered. We use the StarTrack population synthesis code to show how many ULXs will form merging DCOs in the framework of isolated binary evolution. Our merger rate calculation shows that in the local Universe typically $50\%$ of merging BH-BH progenitor binaries have evolved through a ULX phase. This indicates that ULXs can be used to study the origin of LIGO/Virgo sources. We have also estimated that the fraction of observed ULXs that will form merging DCOs in future varies between $5\%$ to $40\%$ depending on common envelope model and metallicity.

scholarly journals Population synthesis of accreting white dwarfs: Rates and evolutionary pathways of H and He novae

2021 ◽  
Author(s):  
Alex J Kemp ◽  
Amanda I Karakas ◽  
Andrew R Casey ◽  
Robert G Izzard ◽  
Ashley J Ruiter ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Binary Systems ◽  
Physical Parameters ◽  
Population Synthesis ◽  
Common Envelope ◽  
Evolutionary Pathways ◽  
Binary Evolution ◽  
Observational Estimate ◽  
Almost All ◽  
Event Rates

Abstract Novae are some of the most commonly detected optical transients and have the potential to provide valuable information about binary evolution. Binary population synthesis codes have emerged as the most effective tool for modelling populations of binary systems, but such codes have traditionally employed greatly simplified nova physics, precluding detailed study. In this work, we implement a model treating H and He novae as individual events into the binary population synthesis code binary_c. This treatment of novae represents a significant improvement on the ‘averaging’ treatment currently employed in modern population synthesis codes. We discuss the evolutionary pathways leading to these phenomena and present nova event rates and distributions of several important physical parameters. Most novae are produced on massive white dwarfs, with approximately 70 and 55 per cent of nova events occurring on O/Ne white dwarfs for H and He novae respectively. Only 15 per cent of H-nova systems undergo a common-envelope phase, but these systems are responsible for the majority of H nova events. All He-accreting He-nova systems are considered post-common-envelope systems, and almost all will merge with their donor star in a gravitational-wave driven inspiral. We estimate the current annual rate of novae in M31 (Andromeda) to be approximately 41 ± 4 for H novae, underpredicting the current observational estimate of $65^{+15}_{-16}$, and 0.14 ± 0.015 for He novae. When varying common-envelope parameters, the H nova rate varies between 20 and 80 events per year.

scholarly journals The Formation of Subdwarf B Stars

2002 ◽  
Vol 187 ◽  
pp. 285-290
Author(s):  
Zhanwen Han ◽  
Philipp Podsiadlowski ◽  
Pierre F.L. Maxted ◽  
Tom R. Marsh ◽  
Natasha Ivanova
Keyword(s):  
Orbital Period ◽  
Mass Function ◽  
Population Synthesis ◽  
B Stars ◽  
Common Envelope ◽  
Subdwarf B Stars ◽  
Sdb Stars ◽  
Period Distribution ◽  
Binary Evolution ◽  
Temperature Surface

AbstractWe performed full binary evolution calculations and carried out binary population synthesis studies in order to investigate the formation of subdwarf B (sdB) stars via the channels of stable Roche lobe overflow (RLOF), common envelope ejection and helium white dwarf mergers. Our model is successful in the explanation of observational properties of sdB stars, e.g. we explained the orbital period – minimum companion mass (log P – Mcomp) diagram, the effective temperature – surface gravity (Teff – log g) diagram, the orbital period distribution, the log(gθ4) (θ = 5040/Teff) distribution, the mass function distribution, the binary fraction of sdB stars, the fraction of sdB binaries with WD companions, the birth rates, the space number densities, etc. We conclude that (a) the first RLOF needs to be more stabilized than commonly assumed, (b) the first stable RLOF is not conservative, (c) common envelope ejection is very efficient.

scholarly journals Effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way

2017 ◽  
Vol 606 ◽  
pp. A97 ◽  
Author(s):  
G. Nandakumar ◽  
M. Schultheis ◽  
M. Hayden ◽  
A. Rojas-Arriagada ◽  
G. Kordopatis ◽  
...  
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Target Selection ◽  
Selection Function ◽  
Population Synthesis ◽  
Sample Distribution ◽  
Stellar Population Synthesis ◽  
Source Sample ◽  
Correction Terms ◽  
Metallicity Distribution

Context. Large spectroscopic Galactic surveys imply a selection function in the way they performed their target selection. Aims. We investigate here the effect of the selection function on the metallicity distribution function (MDF) and on the vertical metallicity gradient by studying similar lines of sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE, and Gaia-ESO), which have different targeting strategies and therefore different selection functions. Methods. We use common fields between the spectroscopic surveys of APOGEE, LAMOST, RAVE (ALR) and APOGEE, RAVE, Gaia-ESO (AGR) and use two stellar population synthesis models, GALAXIA and TRILEGAL, to create mock fields for each survey. We apply the selection function in the form of colour and magnitude cuts of the respective survey to the mock fields to replicate the observed source sample. We make a basic comparison between the models to check which best reproduces the observed sample distribution. We carry out a quantitative comparison between the synthetic MDF from the mock catalogues using both models to understand the effect of the selection function on the MDF and on the vertical metallicity gradient. Results. Using both models, we find a negligible effect of the selection function on the MDF for APOGEE, LAMOST, and RAVE. We find a negligible selection function effect on the vertical metallicity gradients as well, though GALAXIA and TRILEGAL have steeper and shallower slopes, respectively, than the observed gradient. After applying correction terms on the metallicities of RAVE and LAMOST with respect to our reference APOGEE sample, our observed vertical metallicity gradients between the four surveys are consistent within 1σ. We also find consistent gradient for the combined sample of all surveys in ALR and AGR. We estimated a mean vertical metallicity gradient of − 0.241 ± 0.028 dex kpc-1. There is a significant scatter in the estimated gradients in the literature, but our estimates are within their ranges. Conclusions. We have shown that there is a negligible selection function effect on the MDF and the vertical metallicity gradients for APOGEE, RAVE, and LAMOST using two stellar population synthesis models. Therefore, it is indeed possible to combine common fields of different surveys in studies using MDF and metallicity gradients provided their metallicities are brought to the same scale.

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