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  1. Article ; Online: Radiative Particle-in-Cell Simulations of Turbulent Comptonization in Magnetized Black-Hole Coronae.

    Grošelj, Daniel / Hakobyan, Hayk / Beloborodov, Andrei M / Sironi, Lorenzo / Philippov, Alexander

    Physical review letters

    2024  Volume 132, Issue 8, Page(s) 85202

    Abstract: We report results from the first radiative particle-in-cell simulations of strong Alfvénic turbulence in plasmas of moderate optical depth. The simulations are performed in a local 3D periodic box and self-consistently follow the evolution of radiation ... ...

    Abstract We report results from the first radiative particle-in-cell simulations of strong Alfvénic turbulence in plasmas of moderate optical depth. The simulations are performed in a local 3D periodic box and self-consistently follow the evolution of radiation as it interacts with a turbulent electron-positron plasma via Compton scattering. We focus on the conditions expected in magnetized coronae of accreting black holes and obtain an emission spectrum consistent with the observed hard state of Cyg X-1. Most of the turbulence power is transferred directly to the photons via bulk Comptonization, shaping the peak of the emission around 100 keV. The rest is released into nonthermal particles, which generate the MeV spectral tail. The method presented here shows promising potential for ab initio modeling of various astrophysical sources and opens a window into a new regime of kinetic plasma turbulence.
    Language English
    Publishing date 2024-03-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.132.085202
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  2. Article ; Online: Reactivation of Ni-TiO

    Kandarakova, Irina / Yakushkin, Stanislav / Nesterov, Nikolay / Philippov, Alexey / Martyanov, Oleg

    Magnetic resonance in chemistry : MRC

    2023  Volume 61, Issue 11, Page(s) 574–581

    Abstract: Highly dispersed Ni- ... ...

    Abstract Highly dispersed Ni-TiO
    Language English
    Publishing date 2023-09-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 1475029-6
    ISSN 1097-458X ; 0749-1581
    ISSN (online) 1097-458X
    ISSN 0749-1581
    DOI 10.1002/mrc.5385
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Synthetic Images of Magnetospheric Reconnection-Powered Radiation around Supermassive Black Holes.

    Crinquand, Benjamin / Cerutti, Benoît / Dubus, Guillaume / Parfrey, Kyle / Philippov, Alexander

    Physical review letters

    2022  Volume 129, Issue 20, Page(s) 205101

    Abstract: Accreting supermassive black holes can now be observed at the event-horizon scale at millimeter wavelengths. Current predictions for the image rely on hypotheses (fluid modeling, thermal electrons) which might not always hold in the vicinity of the black ...

    Abstract Accreting supermassive black holes can now be observed at the event-horizon scale at millimeter wavelengths. Current predictions for the image rely on hypotheses (fluid modeling, thermal electrons) which might not always hold in the vicinity of the black hole, so that a full kinetic treatment is in order. In this Letter, we describe the first 3D global general-relativistic particle-in-cell simulation of a black-hole magnetosphere. The system displays a persistent equatorial current sheet. Synthetic radio images are computed by ray-tracing synchrotron emission from nonthermal particles accelerated in this current sheet by magnetic reconnection. We identify several time-dependent features of the image at moderate viewing angles: a variable radius of the ring, and hot spots moving along it. In this regime, our model predicts that most of the flux of the image lies inside the critical curve. These results could help promote understanding of future observations of black-hole magnetospheres at improved temporal and spatial resolution.
    Language English
    Publishing date 2022-10-10
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.129.205101
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  4. Article ; Online: Magnetic Hair and Reconnection in Black Hole Magnetospheres.

    Bransgrove, Ashley / Ripperda, Bart / Philippov, Alexander

    Physical review letters

    2021  Volume 127, Issue 5, Page(s) 55101

    Abstract: The no-hair theorem of general relativity states that isolated black holes are characterized by three parameters: mass, spin, and charge. In this Letter we consider Kerr black holes endowed with highly magnetized plasma-filled magnetospheres. Using ... ...

    Abstract The no-hair theorem of general relativity states that isolated black holes are characterized by three parameters: mass, spin, and charge. In this Letter we consider Kerr black holes endowed with highly magnetized plasma-filled magnetospheres. Using general relativistic kinetic plasma and resistive magnetohydrodynamics simulations, we show that a dipole magnetic field on the event horizon opens into a split monopole and reconnects in a plasmoid-unstable current sheet. The no-hair theorem is satisfied, in the sense that all components of the stress-energy tensor decay exponentially in time. We measure the decay time of magnetic flux on the event horizon for plasmoid-dominated reconnection in collisionless and collisional plasma. The reconnecting magnetosphere should be a powerful source of hard x-ray emission when the magnetic field is strong.
    Language English
    Publishing date 2021-08-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.127.055101
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  5. Article ; Online: Collisionless Accretion onto Black Holes: Dynamics and Flares.

    Galishnikova, Alisa / Philippov, Alexander / Quataert, Eliot / Bacchini, Fabio / Parfrey, Kyle / Ripperda, Bart

    Physical review letters

    2023  Volume 130, Issue 11, Page(s) 115201

    Abstract: We study the accretion of collisionless plasma onto a rotating black hole from first principles using axisymmetric general-relativistic particle-in-cell simulations. We carry out a side-by-side comparison of these results to analogous general- ... ...

    Abstract We study the accretion of collisionless plasma onto a rotating black hole from first principles using axisymmetric general-relativistic particle-in-cell simulations. We carry out a side-by-side comparison of these results to analogous general-relativistic magnetohydrodynamic simulations. Although there are many similarities in the overall flow dynamics, three key differences between the kinetic and fluid simulations are identified. Magnetic reconnection is more efficient, and rapidly accelerates a nonthermal particle population, in our kinetic approach. In addition, the plasma in the kinetic simulations develops significant departures from thermal equilibrium, including pressure anisotropy that excites kinetic-scale instabilities, and a large field-aligned heat flux near the horizon that approaches the free-streaming value. We discuss the implications of our results for modeling event-horizon scale observations of Sgr A* and M87 by GRAVITY and the Event Horizon Telescope.
    Language English
    Publishing date 2023-03-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.130.115201
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  6. Article ; Online: Origin of Pulsar Radio Emission.

    Philippov, Alexander / Timokhin, Andrey / Spitkovsky, Anatoly

    Physical review letters

    2020  Volume 124, Issue 24, Page(s) 245101

    Abstract: Since pulsars were discovered as emitters of bright coherent radio emission more than half a century ago, the cause of the emission has remained a mystery. In this Letter we demonstrate that coherent radiation can be directly generated in nonstationary ... ...

    Abstract Since pulsars were discovered as emitters of bright coherent radio emission more than half a century ago, the cause of the emission has remained a mystery. In this Letter we demonstrate that coherent radiation can be directly generated in nonstationary pair plasma discharges which are responsible for filling the pulsar magnetosphere with plasma. By means of large-scale two-dimensional kinetic plasma simulations, we show that if pair creation is nonuniform across magnetic field lines, the screening of electric field by freshly produced pair plasma is accompanied by the emission of waves which are electromagnetic in nature. Using localized simulations of the screening process, we identify these waves as superluminal ordinary (O) modes, which should freely escape from the magnetosphere as the plasma density drops along the wave path. The spectrum of the waves is broadband and the frequency range is comparable to that of observed pulsar radio emission.
    Language English
    Publishing date 2020-07-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.124.245101
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  7. Article ; Online: First-Principles Plasma Simulations of Black-Hole Jet Launching.

    Parfrey, Kyle / Philippov, Alexander / Cerutti, Benoît

    Physical review letters

    2019  Volume 122, Issue 3, Page(s) 35101

    Abstract: Black holes drive powerful plasma jets to relativistic velocities. This plasma should be collisionless, and self-consistently supplied by pair creation near the horizon. We present general-relativistic collisionless plasma simulations of Kerr-black-hole ... ...

    Abstract Black holes drive powerful plasma jets to relativistic velocities. This plasma should be collisionless, and self-consistently supplied by pair creation near the horizon. We present general-relativistic collisionless plasma simulations of Kerr-black-hole magnetospheres which begin from vacuum, inject e^{±} pairs based on local unscreened electric fields, and reach steady states with electromagnetically powered Blandford-Znajek jets and persistent current sheets. Particles with negative energy at infinity are a general feature, and can contribute significantly to black-hole rotational-energy extraction in a variant of the Penrose process. The generated plasma distribution depends on the pair-creation environment, and we describe two distinct realizations of the force-free electrodynamic solution. This sensitivity suggests that plasma kinetics will be useful in interpreting future horizon-resolving submillimeter and infrared observations.
    Language English
    Publishing date 2019-02-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.122.035101
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  8. Article ; Online: Multidimensional Simulations of Ergospheric Pair Discharges around Black Holes.

    Crinquand, Benjamin / Cerutti, Benoît / Philippov, Alexander / Parfrey, Kyle / Dubus, Guillaume

    Physical review letters

    2020  Volume 124, Issue 14, Page(s) 145101

    Abstract: Black holes are known to launch powerful relativistic jets and emit highly variable gamma radiation. How these jets are loaded with plasma remains poorly understood. Spark gaps are thought to drive particle acceleration and pair creation in the black- ... ...

    Abstract Black holes are known to launch powerful relativistic jets and emit highly variable gamma radiation. How these jets are loaded with plasma remains poorly understood. Spark gaps are thought to drive particle acceleration and pair creation in the black-hole magnetosphere. In this Letter, we perform 2D axisymmetric general-relativistic particle-in-cell simulations of a monopole black-hole magnetosphere with a realistic treatment of inverse Compton scattering and pair production. We find that the magnetosphere can self-consistently fill itself with plasma and activate the Blandford-Znajek mechanism. A highly time-dependent spark gap opens near the inner light surface, which injects pair plasma into the magnetosphere. These results may account for the high-energy activity observed in active galactic nuclei and explain the origin of plasma at the base of the jet.
    Language English
    Publishing date 2020-04-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.124.145101
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  9. Article: En U.R.S.S.: un pot de miel de Bachkirie

    Philippov, A

    Gazette apicole Dec 1976, 77 (828)

    1976  

    Title translation A pot of honey from the Bashkir Republic in the USSR.
    Title variant Pot of honey from the Bashkir Republic in the USSR [Apiculture]
    Keywords apiculture ; USSR
    Language French
    Size p. 250-251, 245.
    Document type Article
    ISSN 0016-5506
    Database NAL-Catalogue (AGRICOLA)

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  10. Article: [A study of water autodiffusion in model biological membranes, oriented lipid bilayers].

    Rudakova, M A / Gimatdinov, R S / Philippov, A V

    Biofizika

    2005  Volume 50, Issue 5, Page(s) 878–887

    Abstract: The autodiffusion of water in a multibilayer structure formed by dipalmitoyl phosphatidylcholine and oriented on glass plates was studied by the method of NMR with magnetic field pulse gradient. It was shown that water molecules occur in several states ... ...

    Abstract The autodiffusion of water in a multibilayer structure formed by dipalmitoyl phosphatidylcholine and oriented on glass plates was studied by the method of NMR with magnetic field pulse gradient. It was shown that water molecules occur in several states differing in the degree of interaction with lipid molecules. A spectrum of the coefficients of water autodiffusion in a direction transversal to bilayers was found. The use of samples with different distances between the plates and an analysis of the dependence of the mode of diffuse decay of spin echo on diffusion time and the orientation of the sample, as well as measurements at temperatures above and below the gel-liquid crystal phase transition in cholesterol-containing samples enabled one to discriminate the diffuse decay component responsible for the transbilayer movement of water. The coefficient of bilayer permeability was estimated using the Tanner model. It was shown that the formation of mechanical defects ("cracks") in plane oriented bilayers is the most probable reason for the presence of the water component with the relatively high coefficient of diffusion.
    MeSH term(s) 1,2-Dipalmitoylphosphatidylcholine/chemistry ; Diffusion ; Lipid Bilayers/chemistry ; Water/chemistry
    Chemical Substances Lipid Bilayers ; Water (059QF0KO0R) ; 1,2-Dipalmitoylphosphatidylcholine (2644-64-6)
    Language Russian
    Publishing date 2005-09
    Publishing country Russia (Federation)
    Document type English Abstract ; Journal Article
    ZDB-ID 280283-1
    ISSN 0006-3029
    ISSN 0006-3029
    Database MEDical Literature Analysis and Retrieval System OnLINE

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