scholarly journals Galactic population of black holes in detached binaries with low-mass stripped helium stars: the case of LB-1 (LS V+22 25)

2020 ◽  
Vol 496 (1) ◽  
pp. L6-L10 ◽  
Author(s):  
L R Yungelson ◽  
A G Kuranov ◽  
K A Postnov ◽  
D A Kolesnikov
Keyword(s):  
Black Holes ◽  
Helium Stars ◽  
Galactic Population ◽  
The Galaxy ◽  
Rare Class ◽  
Low Mass ◽  
Black Hole Binary ◽  
Orbital Periods ◽  
Detached Binaries ◽  
Hertzsprung Gap

ABSTRACT We model the Galactic population of detached binaries that harbour black holes with 0.5–1.7 M⊙ companions – remnants of case B mass exchange that rapidly cross Hertzsprung gap after the termination of the Roche lobe overflow or as He-shell burning stars. Several such binaries can be currently present in the Galaxy. The range of MBH in them is about 4–10 M⊙, and the orbital periods are tens to hundreds of days. The unique black hole binary LB-1 fits well into this extremely rare class of double stars.

scholarly journals Case AD, AR, and AS binary evolution and their possible connections with W UMa binaries

2019 ◽  
Vol 492 (2) ◽  
pp. 2731-2738 ◽  
Author(s):  
Dengkai Jiang
Keyword(s):  
Parameter Spaces ◽  
Short Period ◽  
Contact Binaries ◽  
Low Mass ◽  
Orbital Periods ◽  
The Difference ◽  
Binary Evolution ◽  
Detached Binaries ◽  
Period Limit ◽  
The Moment

ABSTRACT Close detached binaries were theoretically predicted to evolve into contact by three subtypes of case A binary evolution, cases AD, AR, and AS, which correspond to the formation of contact during dynamic-, thermal-, and nuclear-time-scale mass transfer phases, respectively. It is unclear, however, what is the difference between contact binaries in these subtypes, and whether all of these subtypes can account for the formation of observed W Ursae Majoris (W UMa) binaries. Using Eggleton’s stellar evolution code with the non-conservative assumption, I obtained the low-mass contact binaries produced by cases AD, AR, and AS at the moment of contact and their parameter spaces. The results support that the progenitors of low-mass contact binaries are detached binaries with orbital periods shorter than $\sim 2\!-\!5\,$ d, and their borderlines depend strongly on the primary mass. In addition, the period–colour relations for cases AR and AS can be in better agreement with that for observed W UMa candidates, but case AD shows a significantly worse agreement. Moreover, cases AR and AS can produce a short-period limit (corresponding to a low-mass limit) at almost any age, e.g. from young age ($\sim 0.2\,$ Gyr) to old age ($\sim 13\,$ Gyr), agreeing with observed W UMa binaries in star clusters, but no such limit occurs for case AD at any age. These results support that cases AR and AS, as opposed to case AD, can lead to W UMa binaries (including young W UMa binaries).

scholarly journals A Model for the Galactic Population of Supersoft X-Ray Sources

1996 ◽  
Vol 158 ◽  
pp. 417-420
Author(s):  
L. Yungelson ◽  
A. Tutukov ◽  
A. Fedorova ◽  
M. Livio ◽  
J. W. Truran
Keyword(s):  
White Dwarfs ◽  
Main Sequence ◽  
X Ray ◽  
Galactic Population ◽  
Transient Sources ◽  
Orbital Periods ◽  
Symbiotic Binaries ◽  
Detached Binaries

AbstractThree major sub-populations of Galactic supersoft X-ray sources may exist: semi-detached binaries with main sequence or subgiant donors, and symbiotic binaries (~550, ~460, and ~600 objects, respectively). Each group contains both permanent and transient sources. The intrinsic and interstellar absorptions reduce the number of observable sources to ~25. We derive the distributions of the sources over orbital periods, masses of the components, and ‘on’-times. The rate at which white dwarfs in Galactic binaries reach MCh is ~ 3 10−5 yr−1. The rate of He-shell detonations which may lead to supernovae may be up to 3 10−4 yr−1.

scholarly journals Black holes, cuspy atmospheres and galaxy formation

2005 ◽  
Vol 363 (1828) ◽  
pp. 739-749 ◽  
Author(s):  
James Binney
Keyword(s):  
Black Holes ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Mass Function ◽  
Galactic Centre ◽  
Potential Wells ◽  
Hot Gas ◽  
The Galaxy ◽  
Low Mass ◽  
The Masses

In cuspy atmospheres, jets driven by supermassive black holes (BHs) offset radiative cooling. The jets fire episodically, but often enough that the cuspy atmosphere does not move very far towards a cooling catastrophe in the intervals of jet inactivity. The ability of energy released on the sub–parsec scale of the BH to balance cooling on scales of several tens of kiloparsecs arises through a combination of the temperature sensitivity of the accretion rate and the way in which the radius of jet disruption varies with ambient density. Accretion of hot gas does not significantly increase BH masses, which are determined by periods of rapid BH growth and star formation when cold gas is briefly abundant at the galactic centre. Hot gas does not accumulate in shallow potential wells. As the Universe ages, deeper wells form, and eventually hot gas accumulates. This gas soon prevents the formation of further stars, since jets powered by the BH prevent it from cooling, and it mops up most cold infalling gas before many stars can form. Thus, BHs set the upper limit to the masses of galaxies. The formation of low–mass galaxies is inhibited by a combination of photoheating and supernova–driven galactic winds. Working in tandem, these mechanisms can probably explain the profound difference between the galaxy luminosity function and the mass function of dark haloes expected in the cold dark matter cosmology.

scholarly journals Dissecting X-ray–Emitting Gas Around the Center of Our Galaxy

Science ◽  
2013 ◽  
Vol 341 (6149) ◽  
pp. 981-983 ◽  
Author(s):  
Q. D. Wang ◽  
M. A. Nowak ◽  
S. B. Markoff ◽  
F. K. Baganoff ◽  
S. Nayakshin ◽  
...  
Keyword(s):  
Black Holes ◽  
Massive Stars ◽  
Supermassive Black Holes ◽  
X Ray ◽  
Accretion Flow ◽  
Active Stars ◽  
The Galaxy ◽  
Low Mass ◽  
Low Levels ◽  
Rule Out

Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy’s SMBH provides an instructive exception, and we present a close-up view of its quiescent x-ray emission based on 3 megaseconds of Chandra observations. Although the x-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission on the basis of the lack of predicted iron (Fe) Kα emission. The extremely weak hydrogen (H)–like Fe Kα line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.

scholarly journals Observed binary populations reflect the Galactic history

2020 ◽  
Vol 641 ◽  
pp. A163 ◽  
Author(s):  
J. Vos ◽  
A. Bobrick ◽  
M. Vučković
Keyword(s):  
Mass Transfer ◽  
Main Sequence ◽  
Fine Tuning ◽  
Red Giants ◽  
Core Mass ◽  
The Galaxy ◽  
History Of ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

Context. Wide hot subdwarf B (sdB) binaries with main-sequence companions are outcomes of stable mass transfer from evolved red giants. The orbits of these binaries show a strong correlation between their orbital periods and mass ratios. The origins of this correlation have, so far, been lacking a conclusive explanation. Aims. We aim to find a binary evolution model which can explain the observed correlation. Methods. Radii of evolved red giants, and hence the resulting orbital periods, strongly depend on their metallicity. We performed a small but statistically significant binary population synthesis study with the binary stellar evolution code MESA. We used a standard model for binary mass loss and a standard metallicity history of the Galaxy. The resulting sdB systems were selected based on the same criteria as was used in observations and then compared with the observed population. Results. We have achieved an excellent match to the observed period-mass ratio correlation without explicitly fine-tuning any parameters. Furthermore, our models produce a very good match to the observed period-metallicity correlation. We predict several new correlations, which link the observed sdB binaries to their progenitors, and a correlation between the orbital period, metallicity, and core mass for subdwarfs and young low-mass helium white dwarfs. We also predict that sdB binaries have distinct orbital properties depending on whether they formed in the Galactic bulge, thin or thick disc, or the halo. Conclusions. We demonstrate, for the first time, how the metallicity history of the Milky Way is imprinted in the properties of the observed post-mass transfer binaries. We show that Galactic chemical evolution is an important factor in binary population studies of interacting systems containing at least one evolved low-mass (Minit <  1.6 M⊙) component. Finally, we provide an observationally supported model of mass transfer from low-mass red giants onto main-sequence stars.

A model for the population of helium stars in the Galaxy: Low-mass stars

2005 ◽  
Vol 49 (11) ◽  
pp. 871-883 ◽  
Author(s):  
L. R. Yungelson ◽  
A. V. Tutukov
Keyword(s):  
Low Mass Stars ◽  
Helium Stars ◽  
The Galaxy ◽  
Low Mass

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.

A Scenario for a Large Number of Low-Mass Black Holes in the Galaxy

1994 ◽  
Vol 423 ◽  
pp. 659 ◽  
Author(s):  
G. E. Brown ◽  
H. A. Bethe
Keyword(s):  
Black Holes ◽  
The Galaxy ◽  
Low Mass

scholarly journals Emerge: Empirical predictions of galaxy merger rates since z ∼ 6

2020 ◽  
Author(s):  
Joseph A O’Leary ◽  
Benjamin P Moster ◽  
Thorsten Naab ◽  
Rachel S Somerville
Keyword(s):  
Galaxy Formation ◽  
Power Law ◽  
Stellar Mass ◽  
Direct Result ◽  
Mass Relation ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Major Merger ◽  
Low Mass ◽  
Merger Rate

Abstract We explore the galaxy-galaxy merger rate with the empirical model for galaxy formation, emerge. On average, we find that between 2 per cent and 20 per cent of massive galaxies (log10(m*/M⊙) ≥ 10.3) will experience a major merger per Gyr. Our model predicts galaxy merger rates that do not scale as a power-law with redshift when selected by descendant stellar mass, and exhibit a clear stellar mass and mass-ratio dependence. Specifically, major mergers are more frequent at high masses and at low redshift. We show mergers are significant for the stellar mass growth of galaxies log10(m*/M⊙) ≳ 11.0. For the most massive galaxies major mergers dominate the accreted mass fraction, contributing as much as 90 per cent of the total accreted stellar mass. We reinforce that these phenomena are a direct result of the stellar-to-halo mass relation, which results in massive galaxies having a higher likelihood of experiencing major mergers than low mass galaxies. Our model produces a galaxy pair fraction consistent with recent observations, exhibiting a form best described by a power-law exponential function. Translating these pair fractions into merger rates results in an inaccurate prediction compared to the model intrinsic values when using published observation timescales. We find the pair fraction can be well mapped to the intrinsic merger rate by adopting an observation timescale that decreases linearly with redshift as Tobs = −0.36(1 + z) + 2.39 [Gyr], assuming all observed pairs merge by z = 0.

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