scholarly journals Drifting through the medium: kicks and self-propulsion of binaries within accretion discs and other environments

2020 ◽  
Vol 498 (2) ◽  
pp. 1963-1972
Author(s):  
Vitor Cardoso ◽  
Caio F B Macedo
Keyword(s):  
Compact Objects ◽  
Accretion Discs ◽  
Medium Density ◽  
Centre Of Mass ◽  
Compact Binaries ◽  
Common Envelope ◽  
Dissipative Effects ◽  
High Speeds ◽  
Analytical Result ◽  
Gravitational Drag

ABSTRACT Compact binaries are within the reach of gravitational and electromagnetic wave detectors, and are important for our understanding of astrophysical environments and the composition of compact objects. There is a vast body of work devoted to the evolution of such binaries in background media, such as in common-envelope evolution, accretion discs and dark matter mini spikes. Here, we explore further gravitationally bound binaries evolving within an environment. We show that dissipative effects such as gravitational drag and accretion impart a momentum to the centre of mass (CM) of asymmetric binaries. We numerically evolve the binaries in a Newtonian setup and show that, depending on the medium density, the CM can accelerate to high speeds – in some cases $300\, {\rm km\, s^{-1}}$ or more – during inspiral, with potentially observable signatures. Our numerical results are fully consistent with an analytical result for the CM evolution at first order in the medium density.

scholarly journals Horizon radiation reaction forces

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Walter D. Goldberger ◽  
Ira Z. Rothstein
Keyword(s):  
Black Hole ◽  
Equations Of Motion ◽  
Finite Size ◽  
Radiation Reaction ◽  
Effective Field ◽  
Compact Objects ◽  
Finite Size Effect ◽  
Binary Black Holes ◽  
Dissipative Effects ◽  
Reaction Forces

Abstract Using Effective Field Theory (EFT) methods, we compute the effects of horizon dissipation on the gravitational interactions of relativistic binary black hole systems. We assume that the dynamics is perturbative, i.e it admits an expansion in powers of Newton’s constant (post-Minkowskian, or PM, approximation). As applications, we compute corrections to the scattering angle in a black hole collision due to dissipative effects to leading PM order, as well as the post-Newtonian (PN) corrections to the equations of motion of binary black holes in non-relativistic orbits, which represents the leading order finite size effect in the equations of motion. The methods developed here are also applicable to the case of more general compact objects, eg. neutron stars, where the magnitude of the dissipative effects depends on non-gravitational physics (e.g, the equation of state for nuclear matter).

scholarly journals Properties of the post-inspiral common envelope ejecta – I. Dynamical and thermal evolution

2019 ◽  
Vol 489 (3) ◽  
pp. 3334-3350 ◽  
Author(s):  
Roberto Iaconi ◽  
Keiichi Maeda ◽  
Orsola De Marco ◽  
Takaya Nozawa ◽  
Thomas Reichardt
Keyword(s):  
Thermal Evolution ◽  
Kinematic Model ◽  
Numerical Approach ◽  
Binary Interaction ◽  
Recombination Energy ◽  
Compact Binaries ◽  
Common Envelope ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae

ABSTRACT We investigate the common envelope binary interaction, that leads to the formation of compact binaries, such as the progenitors of Type Ia supernovae or of mergers that emit detectable gravitational waves. In this work, we diverge from the classic numerical approach that models the dynamic inspiral. We focus instead on the asymptotic behaviour of the common envelope expansion after the dynamic inspiral terminates. We use the SPH code phantom to simulate one of the set-ups from Passy et al., with a 0.88 M⊙, 83 R⊙ RGB primary and a 0.6 M⊙ companion, then we follow the ejecta expansion for 50 yr. Additionally, we utilize a tabulated equation of state including the envelope recombination energy in the simulation (Reichardt et al.), achieving a full unbinding. We show that, as time passes, the envelope’s radial velocities dominate over the tangential ones, hence allowing us to apply an homologous expansion kinematic model to the ejecta. The external layers of the envelope become homologous as soon as they are ejected, but it takes 5000 d (14 yr) for the bulk of the unbound gas to achieve the homologously expanding regime. We observe that the complex distribution generated by the dynamic inspiral evolves into a more ordered, shell-like shaped one in the asymptotic regime. We show that the thermodynamics of the expanding envelope are in very good agreement with those expected for an adiabatically expanding sphere under the homologous condition and give a prediction for the location and temperature of the photosphere assuming dust to be the main source of opacity. This technique ploughs the way to determining the long-term light behaviour of common envelope transients.

scholarly journals Further Evidence of a Brown Dwarf Orbiting the Post-Common Envelope Eclipsing Binary V470 Cam (HS 0705+6700)

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
David Bogensberger ◽  
Fraser Clarke ◽  
Anthony Eugene Lynas-Gray
Keyword(s):  
Mass Loss ◽  
Travel Time ◽  
Centre Of Mass ◽  
Third Body ◽  
Brown Dwarf ◽  
Common Envelope ◽  
Gravitational Pull ◽  
Orbital Periods ◽  
Red Giant ◽  
Time Changes

AbstractSeveral post-common envelope binaries have slightly increasing, decreasing or oscillating orbital periods. One of several possible explanations is light travel-time changes, caused by the binary centre-of-mass being perturbed by the gravitational pull of a third body. Further studies are necessary because it is not clear how a third body could have survived subdwarf progenitor mass-loss at the tip of the Red Giant Branch, or formed subsequently. Thirty-nine primary eclipse times for V470 Cam were secured with the Philip Wetton Telescope during the period 2016 November 25

scholarly journals A systematic study of spiral density waves in the accretion discs of cataclysmic variables

2019 ◽  
Vol 491 (2) ◽  
pp. 2217-2253
Author(s):  
R Ruiz-Carmona ◽  
P J Groot ◽  
D Steeghs
Keyword(s):  
Systematic Study ◽  
Cataclysmic Variables ◽  
Variable Stars ◽  
Spiral Waves ◽  
Compact Objects ◽  
Accretion Discs ◽  
Density Waves ◽  
Ordered Structures ◽  
System Parameters ◽  
Spiral Density Waves

ABSTRACT Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including cataclysmic variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two decades. We present the results of a systematic study searching for spiral density waves in CVs, and report their detection in two of the sixteen observed systems. While most of the systems observed present asymmetric, non-Keplerian accretion discs during outburst, the presence of ordered structures interpreted as spiral density waves is not as ubiquitous as previously anticipated. From a comparison of systems by their system parameters it appears that inclination of the systems may play a major role, favouring the visibility and/or detection of spiral waves in systems seen at high inclination.

Mass outflow rate from accretion discs around compact objects

1999 ◽  
Vol 16 (12) ◽  
pp. 3879-3901 ◽  
Author(s):  
Tapas K Das ◽  
Sandip K Chakrabarti
Keyword(s):  
Compact Objects ◽  
Accretion Discs ◽  
Outflow Rate ◽  
Mass Outflow

scholarly journals Theory of quasi-stationary kinetic dynamos in magnetized accretion discs

2010 ◽  
Vol 6 (S274) ◽  
pp. 228-231 ◽  
Author(s):  
Claudio Cremaschini ◽  
John C. Miller ◽  
Massimo Tessarotto
Keyword(s):  
Magnetic Fields ◽  
Decisive Role ◽  
Accretion Disc ◽  
Compact Objects ◽  
Accretion Discs ◽  
Larmor Radius ◽  
Equilibrium Solutions ◽  
Temperature Anisotropy ◽  
Starting Point ◽  
Dynamo Effect

AbstractMagnetic fields are a distinctive feature of accretion disc plasmas around compact objects (i.e., black holes and neutron stars) and they play a decisive role in their dynamical evolution. A fundamental theoretical question related with this concerns investigation of the so-called gravitational MHD dynamo effect, responsible for the self-generation of magnetic fields in these systems. Experimental observations and theoretical models, based on fluid MHD descriptions of various types support the conjecture that accretion discs should be characterized by coherent and slowly time-varying magnetic fields with both poloidal and toroidal components. However, the precise origin of these magnetic structures and their interaction with the disc plasmas is currently unclear. The aim of this paper is to address this problem in the context of kinetic theory. The starting point is the investigation of a general class of Vlasov-Maxwell kinetic equilibria for axi-symmetric collisionless magnetized plasmas characterized by temperature anisotropy and mainly toroidal flow velocity. Retaining finite Larmor-radius effects in the calculation of the fluid fields, we show how these configurations are capable of sustaining both toroidal and poloidal current densities. As a result, we suggest the possible existence of a kinetic dynamo effect, which can generate a stationary toroidal magnetic field in the disc even without any net radial accretion flow. The results presented may have important implications for equilibrium solutions and stability analysis of accretion disc dynamics.

scholarly journals The Formation and Evolution of Compact Stars in Binaries

2004 ◽  
Vol 194 ◽  
pp. 81-84
Author(s):  
Ronald E. Taam
Keyword(s):  
Angular Momentum ◽  
Mass Loss ◽  
Crucial Role ◽  
Binary Systems ◽  
Compact Objects ◽  
Compact Stars ◽  
Common Envelope ◽  
Formation And Evolution ◽  
The Common ◽  
Magnetic Braking

AbstractThe stellar evolutionary processes responsible for the formation of compact objects in interacting binary systems and their evolution are described. The common envelope phase plays a crucial role in their formation and angular momentum losses associated with magnetic braking and/or mass loss are important for their evolution. An application of these processes provides the evolutionary link between classes of interacting binary systems.

scholarly journals Luminous Red Novae: population models and future prospects

2020 ◽  
Vol 492 (3) ◽  
pp. 3229-3240 ◽  
Author(s):  
George Howitt ◽  
Simon Stevenson ◽  
Alejandro Vigna-Gómez ◽  
Stephen Justham ◽  
Natasha Ivanova ◽  
...  
Keyword(s):  
Binary Stars ◽  
Luminosity Function ◽  
Indirect Evidence ◽  
Compact Objects ◽  
Evolutionary Pathway ◽  
Common Envelope ◽  
Long Duration ◽  
Red Supergiants ◽  
The Impact ◽  
Stellar Mergers

ABSTRACT A class of optical transients known as Luminous Red Novae (LRNe) have recently been associated with mass ejections from binary stars undergoing common-envelope evolution. We use the population synthesis code COMPAS to explore the impact of a range of assumptions about the physics of common-envelope evolution on the properties of LRNe. In particular, we investigate the influence of various models for the energetics of LRNe on the expected event rate and light curve characteristics, and compare with the existing sample. We find that the Galactic rate of LRNe is ∼0.2 yr−1, in agreement with the observed rate. In our models, the luminosity function of Galactic LRNe covers multiple decades in luminosity and is dominated by signals from stellar mergers, consistent with observational constraints from iPTF and the Galactic sample of LRNe. We discuss how observations of the brightest LRNe may provide indirect evidence for the existence of massive (>40 M⊙) red supergiants. Such LRNe could be markers along the evolutionary pathway leading to the formation of double compact objects. We make predictions for the population of LRNe observable in future transient surveys with the Large Synoptic Survey Telescope and the Zwicky Transient Facility. In all plausible circumstances, we predict a selection-limited observable population dominated by bright, long-duration events caused by common envelope ejections. We show that the Large Synoptic Survey Telescope will observe 20–750 LRNe per year, quickly constraining the luminosity function of LRNe and probing the physics of common-envelope events.

scholarly journals Gravitational waves from in-spirals of compact objects in binary common-envelope evolution

2020 ◽  
Vol 493 (4) ◽  
pp. 4861-4867 ◽  
Author(s):  
Yonadav Barry Ginat ◽  
Hila Glanz ◽  
Hagai B Perets ◽  
Evgeni Grishin ◽  
Vincent Desjacques
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Compact Objects ◽  
Dynamical Friction ◽  
Next Generation ◽  
Common Envelope ◽  
Dissipative Processes

ABSTRACT Detection of gravitational-wave (GW) sources enables the characterization of binary compact objects (COs) and of their in-spiral. However, other dissipative processes can affect the in-spiral. Here, we show that the in-spiral of COs through a gaseous common envelope (CE) arising from an evolved stellar companion produces a novel type of GW sources, whose evolution is dominated by the dissipative gas dynamical friction effects from the CE, rather than the GW emission itself. The evolution and properties of the GW signals differ from those of isolated gas-poor mergers significantly. We find characteristic strains of ∼10−23–10−21 ($10\, {\rm kpc}/{D}$) for such sources – observable by next-generation space-based GW detectors (at rates of once per a few centuries for LISA, and about once a year for BBO). The evolution of the GW signal can serve as a probe of the interior regions of the evolved star, and the final stages of CE evolution, otherwise inaccessible through other observational means. Moreover, such CE mergers are frequently followed by observable explosive electromagnetic counterparts and/or the formation of exotic stars.

scholarly journals Gravitational waves from supernova mass loss and natal kicks in close binaries

2019 ◽  
Vol 490 (4) ◽  
pp. 5560-5566 ◽  
Author(s):  
A Miguel Holgado ◽  
Paul M Ricker
Keyword(s):  
Mass Loss ◽  
Gravitational Waves ◽  
Dynamical Evolution ◽  
Close Binaries ◽  
Orbital Energy ◽  
Core Collapse ◽  
Compact Binaries ◽  
Common Envelope ◽  
Binary Formation ◽  
Hubble Time

ABSTRACT Some fraction of compact binaries that merge within a Hubble time may have formed from two massive stars in isolation. For this isolated-binary formation channel, binaries need to survive two supernova (SN) explosions in addition to surviving common-envelope evolution. For the SN explosions, both the mass loss and natal kicks change the orbital characteristics, producing either a bound or unbound binary. We show that gravitational waves (GWs) may be produced not only from the core-collapse SN process, but also from the SN mass loss and SN natal kick during the pre-SN to post-SN binary transition. We model the dynamical evolution of a binary at the time of the second SN explosion with an equation of motion that accounts for the finite time-scales of the SN mass loss and the SN natal kick. From the dynamical evolution of the binary, we calculate the GW burst signals associated with the SN natal kicks. We find that such GW bursts may be of interest to future mid-band GW detectors like DECIGO. We also find that the energy radiated away from the GWs emitted due to the SN mass loss and natal kick may be a significant fraction, ${\gtrsim }10{\,{\rm {per\, cent}}}$, of the post-SN binary’s orbital energy. For unbound post-SN binaries, the energy radiated away in GWs tends to be higher than that of bound binaries.

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