Igor Dmitrievich Novikov (on his 80th birthday)

Бисноватый-Коган, Г. С.; Doroshkevich, A. G.; Zelenyǐ, L. M.; Kardashëv, N. S.; Kolachevsky, Nikolai N.; Komberg, B. V.; Kompaneets, D.A.; Lukash, V. N.; Mesyats, G. A.; Pariiskii, Yu. N.; Рубаков, Валерий А.; Черепащук, А. М.

doi:10.3367/ufne.0186.201601f.0105

Cited by 5 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4) suggests that a hylotropic, pure-accretion regime can be stable over one or two orders of magnitude in mass. Additional effects, such as rotation, could extend the mass range further by stabilising the star against the GR instability (Fowler 1966;Bisnovatyi-Kogan et al 1967).…”

Section: Hydrostatic Equilibriummentioning

confidence: 99%

Maximally accreting supermassive stars: a fundamental limit imposed by hydrostatic equilibrium

Haemmerlé

Meynet

Mayer

et al. 2019

A&A

View full text Add to dashboard Cite

Context. Major mergers of gas-rich galaxies provide promising conditions for the formation of supermassive black holes (SMBHs; 10 5 M ) by direct collapse because they can trigger mass inflows as high as 10 4 − 10 5 M yr −1 on sub-parsec scales. However, the channel of SMBH formation in this case, either dark collapse (direct collapse without prior stellar phase) or supermassive star (SMS; 10 4 M ), remains unknown. Aims. Here, we investigate the limit in accretion rate up to which stars can maintain hydrostatic equilibrium. Methods. We compute hydrostatic models of SMSs accreting at 1 -1000 M yr −1 , and estimate the departures from equilibrium a posteriori by taking into account the finite speed of sound. Results. We find that stars accreting above the atomic cooling limit ( 10 M yr −1 ) can only maintain hydrostatic equilibrium once they are supermassive. In this case, they evolve adiabatically with a hylotropic structure, that is, entropy is locally conserved and scales with the square root of the mass coordinate. Conclusions. Our results imply that stars can only become supermassive by accretion at the rates of atomically cooled haloes (∼ 0.1 − 10 M yr −1 ). Once they are supermassive, larger rates are possible.

show abstract

Section: Hydrostatic Equilibriummentioning

confidence: 99%

Maximally accreting supermassive stars: a fundamental limit imposed by hydrostatic equilibrium

Haemmerlé

Meynet

Mayer

et al. 2019

A&A

View full text Add to dashboard Cite

show abstract

“…It is believed that SMSs form when colliding gas residing in metal-, dust-, and H 2 -poor halos build up sufficient radiation pressure to inhibit fragmentation and the formation of small stars [79][80][81][82]. As thermal emission and turbulence driven by magnetic viscosity take place, the star shrinks and spins up to the mass-shedding limit [20,22,83]. It then evolves in a quasistationary manner until reaching the onset of relativistic radial instability and eventually collapses to form a seed of a SMBH [18].…”

Section: B Initial Datamentioning

confidence: 99%

“…Idealized SMSs are objects supported dominantly by radiation pressure P r , which can be well described by a Γ = 4/3 adiabatic index, or an n = 3 polytropic equation of state [17][18][19]. SMSs are likely to be highly spinning and turbulent viscosity induced by magnetic fields would keep them in uniform rotation [20][21][22][23]. The critical configuration of a SMS at the mass-shedding limit along a quasistationary evolution sequence is set by the onset of a relativistic radial instability.…”

Section: Introductionmentioning

confidence: 99%

Simulating the magnetorotational collapse of supermassive stars: Incorporating gas pressure perturbations and different rotation profiles

2018

View full text Add to dashboard Cite

Collapsing supermassive stars (SMSs) with masses M 10 4−6 M have long been speculated to be the seeds that can grow and become supermassive black holes (SMBHs). We previously performed general relativistic magnetohydrodynamic (GRMHD) simulations of marginally stable Γ = 4/3 polytropes uniformly rotating at the mass-shedding limit and endowed initially with a dynamically unimportant dipole magnetic field to model the direct collapse of SMSs. These configurations are supported entirely by thermal radiation pressure and reliably model SMSs with M 10 6 M . We found that around 90% of the initial stellar mass forms a spinning black hole (BH) remnant surrounded by a massive, hot, magnetized torus, which eventually launches a magnetically-driven jet. SMSs could be therefore sources of ultra-long gamma-ray bursts (ULGRBs). Here we perform GRMHD simulations of Γ 4/3, polytropes to account for the perturbative role of gas pressure in SMSs with M 10 6 M . We also consider different initial stellar rotation profiles. The stars are initially seeded with a dynamically weak dipole magnetic field that is either confined to the stellar interior or extended from its interior into the stellar exterior. We calculate the gravitational wave burst signal for the different cases. We find that the mass of the black hole remnant is 90%−99% of the initial stellar mass, depending sharply on Γ−4/3 as well as on the initial stellar rotation profile. After t ∼ 250 − 550M ≈ 1 − 2 × 10 3 (M/10 6 M )s following the appearance of the BH horizon, an incipient jet is launched and it lasts for ∼ 10 4 − 10 5 (M/10 6 M )s, consistent with the duration of long gamma-ray bursts. Our numerical results suggest that the Blandford-Znajek mechanism powers the incipient jet. They are also in rough agreement with our recently proposed universal model that estimates accretion rates and electromagnetic (Poynting) luminosities that characterize magnetized BHdisk remnant systems that launch a jet. This model helps explain why the outgoing electromagnetic luminosities computed for vastly different BH-disk formation scenarios all reside within a narrow range (∼ 10 52±1 ergs −1 ), roughly independent of M . PACS numbers: 04.25. 47.75.+f, 95.30.Qd

show abstract

“…The progenitor object in such a "direct collapse" scenario is often referred to as a supermassive star (SMS). The properties of SMSs have been the subject of an extensive body of literature (see, e.g., Iben (1963); Hoyle & Fowler (1963); Chandrasekhar (1964); Bisnovatyi-Kogan et al (1967); Wagoner (1969); Appenzeller & Fricke (1972); Begelman & Rees (1978); Fuller et al (1986) for some early references, as well as Shapiro & Teukolsky (1983, hereafter ST), Zeldovich & Novikov (1971), and Kippenhahn et al (2012) for textbook treatments). Numerous authors and groups have studied possible avenues for their formation (see, e.g., Schleicher et al (2013); Hosokawa et al (2013); Sakurai et al (2015); Umeda et al (2016); Woods et al (2017); Haemmerlé et al (2018b,a); see also Wise et al (2019) for recent simulations in the context of cosmological evolutions) as well as their ability to avoid fragmentation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Maximally rotating supermassive stars at the onset of collapse: effects of gas pressure

Dennison

Baumgarte

Shapiro

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The "direct collapse" scenario has emerged as a promising evolutionary track for the formation of supermassive black holes early in the Universe. In an idealized version of such a scenario, a uniformly rotating supermassive star spinning at the mass-shedding (Keplerian) limit collapses gravitationally after it reaches a critical configuration. Under the assumption that the gas is dominated by radiation pressure, this critical configuration is characterized by unique values of the dimensionless parameters J/M 2 and R p /M, where J is the angular momentum, R p the polar radius, and M the mass. Motivated by a previous perturbative treatment we adopt a fully nonlinear approach to evaluate the effects of gas pressure on these dimensionless parameters for a large range of masses. We find that gas pressure has a significant effect on the critical configuration even for stellar masses as large as M 10 6 M . We also calibrate two approximate treatments of the gas pressure perturbation in a comparison with the exact treatment, and find that one commonly used approximation in particular results in increasing deviations from the exact treatment as the mass decreases, and the effects of gas pressure increase. The other approximation, however, proves to be quite robust for all masses M 10 4 M . Approx. I, β = 0.001 MS J = 16.00 J = 16.50 J = 17.00 J = 17.50 J = 17.75 J = 18.00 J = 18.25 J = 18.42 J = 18.75 J = 19.00 Turn. Pt. Crit. Pt. 0.0 0.5 1.0 1.5 2.0 ×10 −8 4.50 4.51 4.52 4.53 4.54 4.55 Approx. II, β = 0.001 MS J = 16.00 J = 16.50 J = 17.00 J = 17.50 J = 17.75 J = 18.00 J = 18.25 J = 18.65 J = 18.75 J = 19.00 Turn. Pt. Crit. Pt. 0.0 0.5 1.0 1.5 2.0 ×10 −8 4.36 4.38 4.40 4.42 M Exact, β = 0.004 MS J = 14.00 J = 14.50 J = 15.00 J = 15.50 J = 16.00 J = 16.25 J = 16.50 J = 16.75 J = 18.00 J = 20.00 Turn. Pt. Crit. Pt. 0.0 0.5 1.0 1.5 2.0 ×10 −8 4.36 4.38 4.40 4.42 Approx. I, β = 0.004 MS J = 14.00 J = 14.50 J = 15.00 J = 15.50 J = 16.00 J = 16.25 J = 16.50 J = 16.75 J = 18.00 J = 20.00 Turn. Pt. Crit. Pt. 0.0 0.5 1.0 1.5 2.0 ×10 −8 4.42 4.44 4.46 4.48 Approx. II, β = 0.004 MS J = 14.00 J = 14.50 J = 15.00 J = 15.50 J = 16.00 J = 16.25 J = 16.50 J = 17.35 J = 18.00 J = 20.00 Turn. Pt. Crit. Pt. 0 2 4 6 ×10 −8 3.900 3.925 3.950 3.975 4.000 4.025 4.050 M Exact, β = 0.016 MS J = 8.00 J = 10.00 J = 10.50 J = 11.00 J = 11.50 J = 11.75 J = 12.00 J = 12.18 J = 16.00 J = 18.00 Turn. Pt. Crit. Pt. Approx. I, β = 0.016 MS J = 8.00 J = 10.00 J = 10.50 J = 11.00 J = 11.50 J = 11.75 J = 12.00 J = 12.10 J = 16.00 J = 18.00 Turn. Pt. Crit. Pt. Approx. II, β = 0.016 MS J = 8.00 J = 10.00 J = 10.50 J = 11.00 J = 11.50 J = 11.75 J = 12.00 J = 13.48 J = 16.00 J = 18.00 Turn. Pt. Crit. Pt. MS J = 6.00 J = 8.00 J = 8.25 J = 8.50 J = 8.75 J = 9.00 J = 9.25 J = 9.44 J = 11.00 J = 12.00 Turn. Pt. Crit. Pt. Approx. I, β = 0.028 MS J = 6.00 J = 8.00 J = 8.25 J = 8.50 J = 8.75 J = 9.00 J = 9.25 J = 9.26 J = 11.00 J = 12.00 Turn. Pt. Crit. Pt. Approx. II, β = 0.028 MS J = 6.00 J = 8.00 J = 8.25 J = 8.50 J = 8.75 J = 9.00 J = 9.25 J = 10.88 J = 11.00 J = ...

show abstract

Igor Dmitrievich Novikov (on his 80th birthday)

Cited by 5 publications

References 0 publications

Maximally accreting supermassive stars: a fundamental limit imposed by hydrostatic equilibrium

Maximally accreting supermassive stars: a fundamental limit imposed by hydrostatic equilibrium

Simulating the magnetorotational collapse of supermassive stars: Incorporating gas pressure perturbations and different rotation profiles

Maximally rotating supermassive stars at the onset of collapse: effects of gas pressure

Contact Info

Product

Resources

About