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Showing 1–12 of 12 results
Advanced filters: Author: Vladimir Karas Clear advanced filters

  • Black-hole activity feedback is intensively studied on both galaxy-cluster scales and parsec scales. There are, however, many open questions about how the close surroundings of supermassive black holes affect large-scale structure and vice versa.

    • Michal Zajaček
    • Bożena Czerny
    • Vladimír Karas
    News & Views
    Nature Astronomy
    Volume: 6, P: 1008-1010

  • S-cluster is a group of high-velocity stars near the supermassive black hole in the center of our Galaxy, and binary stars have been predicted in the S-cluster, but not detected. Here, the authors show detection of a spectroscopic binary in the S-cluster.

    • Florian Peißker
    • Michal Zajaček
    • Vladimír Karas
    ResearchOpen Access
    Nature Communications
    Volume: 15, P: 1-11

  • The accretion geometry of X-ray binary Cygnus X-3 is determined here from IXPE observations. X-ray polarization reveals a narrow funnel with reflecting walls, which focuses emission, making Cyg X-3 appear as an ultraluminous X-ray source.

    • Alexandra Veledina
    • Fabio Muleri
    • Silvia Zane
    Research
    Nature Astronomy
    Volume: 8, P: 1031-1046

  • X-ray polarization measurements of the Crab nebula and pulsar by the IXPE satellite reveal a global toroidal magnetic field with large variations in local polarization, suggesting a more complex turbulence distribution than anticipated.

    • Niccolò Bucciantini
    • Riccardo Ferrazzoli
    • Silvia Zane
    Research
    Nature Astronomy
    Volume: 7, P: 602-610

  • A study reports the measurement of the polarization degree and angle of X-rays from Sagittarius A* reflected off a nearby cloud, indicating an X-ray flare about 200 years ago.

    • Frédéric Marin
    • Eugene Churazov
    • Silvia Zane
    Research
    Nature
    Volume: 619, P: 41-45

  • X-ray polarimetry observations with the Imaging X-ray Polarimetry Explorer constrain the accretion geometry in an X-ray pulsar and provide evidence for a misalignment of the spin, magnetic and orbital axes in Her X-1.

    • Victor Doroshenko
    • Juri Poutanen
    • Fei Xie
    Research
    Nature Astronomy
    Volume: 6, P: 1433-1443

  • Polarization can exceed 60% at the leading edge of the inner part of the Vela pulsar wind nebula; in contrast with the case of the supernova remnant, the electrons in the pulsar wind nebula are accelerated with little or no turbulence in a highly uniform magnetic field.

    • Fei Xie
    • Alessandro Di Marco
    • Silvia Zane
    Research
    Nature
    Volume: 612, P: 658-660

  • Polarization measurements are reported for the blazar Mk501, revealing a degree of X-ray polarization that is more than twice the optical value and supporting the shock-accelerated energy-stratified electron population scenario.

    • Ioannis Liodakis
    • Alan P. Marscher
    • Silvia Zane
    ResearchOpen Access
    Nature
    Volume: 611, P: 677-681

  • Multiwavelength observations of a galactic nucleus exhibit quasi-periodic X-ray eruptions (QPEs) that repeat every 22 days, a timescale intermediate between those of other QPEs and so-called repeating nuclear transients. The eruptions are likely to be driven by the interaction between an orbiting body and a central massive black hole.

    • Muryel Guolo
    • Dheeraj R. Pasham
    • Elizabeth C. Ferrara
    Research
    Nature Astronomy
    Volume: 8, P: 347-358

  • In June 2022, the IXPE satellite observed a shock passing through the jet of active galaxy Markarian 421. The rotation of the X-ray-polarized radiation over a 5-day period revealed that the jet contains a helical magnetic field.

    • Laura Di Gesu
    • Herman L. Marshall
    • Silvia Zane
    Research
    Nature Astronomy
    Volume: 7, P: 1245-1258

  • This analysis describes the results of three Cell Tracking Challenge editions for examining the performance of cell segmentation and tracking algorithms and provides practical feedback for users and developers.

    • Vladimír Ulman
    • Martin Maška
    • Carlos Ortiz-de-Solorzano
    Research
    Nature Methods
    Volume: 14, P: 1141-1152