Stellar binaries in galactic nuclei: tidally stimulated mergers followed by tidal disruptions

We investigate interactions of stellar binaries in galactic nuclear clusters with a massive black hole (MBH). We consider binaries on highly eccentric orbits around the MBH that change due to random gravitational interactions with other stars in the nuclear stellar cluster. The pericenters of the orbits perform a random walk, and we consider cases where this random walk slowly brings the binary to the Hills tidal separation radius (the so-called empty loss-cone regime). However, we find that in a majority of cases the expected separation does not occur and instead the members of the binary merge together. This happens because the binary's eccentricity is excited by tidal interactions with the MBH, and the relative excursions of the internal eccentricity of the binary far exceed those in its internal semimajor axis. This frequently reduces the pericenter separation to values below typical stellar diameters, which induces a significant fraction of such binaries to merge ($\gtrsim 75\%$ in our set of numerical experiments). Stellar tides do not appreciably change the total rate of mergers but circularise binaries, leading to a significant fraction of low-eccentricity, low-impact-velocity mergers. Some of the stellar merger products will then be tidally disrupted by the MBH within $\sim 10^6$ years. If the merger strongly enhances the magnetic field of the merger product, this process could explain observations of prompt relativistic jet formation in some tidal disruption events.

Similar Publications

Electrons at relativistic speeds, diffusing in magnetic fields, cause copious emission at radio frequencies in both clusters of galaxies and radio galaxies, through the non-thermal radiation emission called synchrotron. However, the total power radiated through this mechanism is ill constrained, as the lower limit of the electron energy distribution, or low-energy cutoffs, for radio emission in galaxy clusters and radio galaxies have not yet been determined. This lower limit, parametrized by the lower limit of the electron momentum - pmin - is critical for estimating the energetics of non-thermal electrons produced by cluster mergers or injected by radio galaxy jets, which impacts the formation of large-scale structure in the universe, as well as the evolution of local structures inside galaxy clusters. Read More

The abundance of accelerators and the ambient conditions make Cygnus X a natural laboratory for studying the life cycle of cosmic-rays (CRs). This naturally makes the Cygnus X complex a highly interesting source in neutrino astronomy, in particular concerning a possible detection with the IceCube Neutrino Observatory, which has a good view of the northern hemisphere. In this paper, we model the multiwavelength spectrum of the Cygnus, for the first time using a broad data set from radio, MeV (COMPTEL), GeV (Fermi), TeV (Argo) and 10s of TeV (Milagro) energies. Read More

Authors: A. Aduszkiewicz, Y. Ali, E. V. Andronov, T. Antićić, B. Baatar, M. Baszczyk, S. Bhosale, A. Blondel, M. Bogomilov, A. Brandin, A. Bravar, J. Brzychczyk, S. A. Bunyatov, O. Busygina, H. Cherif, M. Ćirković, T. Czopowicz, A. Damyanova, N. Davis, H. Dembinski, M. Deveaux, W. Dominik, P. Dorosz, J. Dumarchez, R. Engel, A. Ereditato, S. Faas, G. A. Feofilov, Z. Fodor, C. Francois, A. Garibov, X. Garrido, M. Gaździcki, M. Golubeva, K. Grebieszkow, F. Guber, A. Haesler, A. E. Hervé, J. Hylen, S. N. Igolkin, A. Ivashkin, S. R. Johnson, K. Kadija, E. Kaptur, M. Kiełbowicz, V. A. Kireyeu, V. Klochkov, V. I. Kolesnikov, D. Kolev, A. Korzenev, V. N. Kovalenko, K. Kowalik, S. Kowalski, M. Koziel, A. Krasnoperov, W. Kucewicz, M. Kuich, A. Kurepin, D. Larsen, A. László, T. V. Lazareva, M. Lewicki, B. Lundberg, B. Łysakowski, V. V. Lyubushkin, M. Maćkowiak-Pawłowska, B. Maksiak, A. I. Malakhov, D. Manić, A. Marchionni, A. Marcinek, A. D. Marino, I. C. Mariş, K. Marton, H. -J. Mathes, T. Matulewicz, V. Matveev, G. L. Melkumov, A. O. Merzlaya, B. Messerly, Ł. Mik, G. B. Mills, S. Morozov, S. Mrówczyński, Y. Nagai, M. Naskręt, V. Ozvenchuk, V. Paolone, M. Pavin, O. Petukhov, C. Pistillo, R. Płaneta, P. Podlaski, B. A. Popov, M. Posiadała, S. Puławski, J. Puzović, R. Rameika, W. Rauch, M. Ravonel, R. Renfordt, E. Richter-Wąs, D. Röhrich, E. Rondio, M. Roth, M. Ruprecht, B. T. Rumberger, A. Rustamov, M. Rybczynski, A. Rybicki, A. Sadovsky, K. Schmidt, I. Selyuzhenkov, A. Yu. Seryakov, P. Seyboth, M. Słodkowski, A. Snoch, P. Staszel, G. Stefanek, J. Stepaniak, M. Strikhanov, H. Ströbele, T. Šuša, M. Szuba, A. Taranenko, A. Tefelska, D. Tefelski, V. Tereshchenko, A. Toia, R. Tsenov, L. Turko, R. Ulrich, M. Unger, F. F. Valiev, D. Veberič, V. V. Vechernin, M. Walewski, A. Wickremasinghe, C. Wilkinson, Z. Włodarczyk, A. Wojtaszek-Szwarc, O. Wyszyński, L. Zambelli, E. D. Zimmerman, R. Zwaska

We present measurements of $\rho^0$, $\omega$ and K$^{*0}$ spectra in $\pi^{-} + $C production interactions at 158 GeV/c and $\rho^0$ spectra at 350 GeV/c using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman's variable $x_\text{F}$ in the range $0 < x_\text{F} < 1$ and $0 < x_\text{F} < 0.5$ for 158 GeV/c and 350 GeV/c respectively. Read More

The neutrino burst detected during supernova SN1987A is explained in a strangeon star model, in which it is proposed that a pulsar-like compact object is composed of strangeons (strangeon: an abbreviation of "strange nucleon"). A nascent strangeon star's initial internal energy is calculated, with the inclusion of pion excitation (energy around 10^53 erg, comparable to the gravitational binding energy of a collapsed core). A liquid-solid phase transition at temperature ~ 1-2 MeV may occur only a few ten-seconds after core-collapse, and the thermal evolution of strangeon star is then modeled. Read More

We describe a new analytical model for the accretion of particles from a rotating and charged spherical shell of dilute collisionless plasma onto a rotating and charged black hole. By assuming a continuous injection of particles at the spherical shell and by treating the black hole and a featureless accretion disc located in the equatorial plane as passive sinks of particles we build a stationary accretion model. This may then serve as a toy model for plasma feeding an accretion disc around a charged and rotating black hole. Read More

We report on the first experimental observation of a current-driven instability developing in a quasi-neutral matter-antimatter beam. Strong magnetic fields ($\geq$ 1 T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma.The experimentally determined equipartition parameter of $\epsilon_B \approx 10^{-3}$, is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. Read More

We examine the effects of a global magnetic field and outflow on radiatively inefficient accretion flow (RIAF) in the presence of magnetic resistivity. We find a self-similar solutions for the height integrated equations that govern the behavior of the flow. We use the mixing length mechanism for studying the convection parameter. Read More

We present a one-parameter family of stationary, asymptotically flat solutions of the Einstein-Maxwell equations with only a mild singularity, which are endowed with mass, angular momentum, a dipole magnetic moment and a quadrupole electric moment. We briefly analyze the structure of this solution, which we interpret as a system of two extreme co-rotating black holes with equal masses and electric charges, and opposite magnetic and gravimagnetic charges, held apart by an electrically charged, magnetized string which also acts as a Dirac-Misner string. Read More

Understanding the origin of the flaring activity from the Galactic center supermassive black hole, Sagittarius A*, is a major scientific goal of the NuSTAR Galactic plane survey campaign. We report on the data obtained between July 2012 and April 2015, including 27 observations on Sgr A* with a total exposure of ~ 1 Ms. We found a total of ten X-ray flares detected in the NuSTAR observation window, with luminosities in the range of $L_{3-79~keV}$~$(0. Read More