No abstract

The accretion disk response to a loss of 5% of the mass of the accretor formed by a stellar-mass binary black hole coalescence has been simulated. The parameters of the initial binary system correspond to the gravitational-wave source GW170814. We performed a series of simulations of models with radiative and convective heat transfer mechanisms and various accretion rates. The models took into account radiation pressure and adiabatic vertical gas expansion. Reducing the mass of the accretor due to emission of gravitational waves led to a strong hydrodynamic disturbance of the disk that developed in less than one second into a shock wave. As a result of shock heating, the luminosity of convective disks increased by 3–5 orders of magnitude and reached 1043 erg s−1. The luminosity of radiative disks increased by 1–2 orders of magnitude, to 1040 erg s−1. If the source is as far as 540 Mpc (as in the case of the GW170814 event), disk brightening could be detected by the XMM-Newton X-ray observatory.

We consider scenario of merger of two stellar mass black holes surrounded by an accretion disk. Due to emission of gravitational waves, the mass of the central object decreases and accretion disk experiences perturbation. Calculations show that the main consequence of this disturbance is formation of a shock wave propagating from the center of the disk to its periphery. Light curve is computed and duration of the flash is estimated under assumption that the flash terminates when the luminosity returns to the initial value.It is shown that, if the total mass of the merging binary is 55 M ⊙ (like in the event GW170814), the flash produced by the shock will increase bolometric luminosity of the disk by 4 6 orders of magnitude, up to 10 45 erg/s (absolute stellar magnitude −23.8 m ). With account of the distance to the source (540 Mpc) and for reasonable assumptions on the parameters of the accretion disk, it turns out that the apparent magnitude of the flash at the maximum of the spectral flux density should be 12.8 m 14.2 m , while duration of the flash few minutes.The main part of the shock radiation flux is emitted in the X-ray and gamma-ray ranges. In the spectral band of the EPIC instrument of the XMM-Newton observatory or the telescope eROSITA of the Spectrum-RG observatory (0.3 10 keV), luminosity will increase by 3 4 orders of magnitude (7.5 m 10 m ), up to 10 44 erg/s, corresponding to the apparent stellar magnitude about 17 m . Luminosity is at maximum in the observational band of the IBIS instrument of the INTEGRAL observatory (20 keV 10 MeV) and will be 10 44 10 45 erg/s, corresponding to the apparent flux 10 −4 photons per /cm 2 /s/keV at the wavelength ∼ 100 keV. From the far UV to the longer wavelengths, the brightening is virtually absent at the wavelength 10 eV luminosity, approximately, doubles and corresponds to the absolute magnitude −6 m and visual one 32 m . * bisikalo@inasan.ru † zhilkin@inasan.ru ‡ kurbatov@inasan.ru Object M 1 , M 2 [M ⊙ ] ∆M/(M 1 + M 2 ) [%] D [Mpc] GW150914 [1] 36 +5 −4 , 29 +4 −4 3.3 5.2 410 +160 −180 GW151226 [2] 14.2 +8.3 −3.7 , 7.5 +2.3 −2.3 2.9 5.5 440 +180 −190 GW170104 [3] 31.2 +8.4 −6.0 , 19.4 +8.3 −5.9 2.3 5.7 880 +450 −390 GW170608 [4] 12 +7 −2 , 7 +2 −2 2.8 5.1 340 +140 −140 GW170814 [5] 30.5 +5.7 −3.0 , 25.3 +2.8 −4.2 4.0 5.8 540 +130 −210