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Volume 5 Issue 5, May 2021

New sources of neutrinos

Observations of a high-energy neutrino led astronomers to identify a tidal disruption event as its likely source. The event was triggered by a star passing too close to a supermassive black hole. A mildly relativistic outflow was detected, confirming that the black hole can accelerate these cosmic particles.

See Stein et al.

Image: DESY, Science Communication Lab Cover Design: Bethany Vukomanovic.


  • Be it neutrinos, ultra-high-energy photons or gravitational waves, new cosmic messengers have expanded the available discovery space of astronomy by exploring previously inaccessible astrophysical environments.



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Comment & Opinion

  • Astronomy and astrophysics in Vietnam are still in their infancy. Current efforts to stimulate interest in the general public, to foster the teaching of basic knowledge, and to develop research on frontline topics are described.

    • Ngoc Diep Pham
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Books & Arts

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Research Highlights

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News & Views

  • The detection of two transition metals in the remnant of a supernova lends support to a mechanism for the explosion of a massive star called the neutrino-driven convective supernova engine, where a plume of hot material re-invigorates a stalled shockwave.

    • Patrick Young
    News & Views
  • Tidal disruption events are an excellent probe for supermassive black holes in distant inactive galaxies because they emit bright multi-wavelength flares that last several months to years. AT2019dsg represents the first potential association of neutrino emission with such an explosive event.

    • Kimitake Hayasaki
    News & Views
  • The short and regular bursts in massive black hole systems known as quasi-periodic eruptions have intrigued — and puzzled — astronomers since their discovery. Two such sources recently discovered by SRG/eROSITA suggest that they could be the electromagnetic counterparts to a type of gravitational-wave sources called extreme mass-ratio inspirals.

    • Tingting Liu
    News & Views
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  • The formation mechanism of the most common type of planet in the Galaxy, those with masses between those of the Earth and Neptune, is far from clear. However, simulations of disk fragmentation presented here, which incorporate a spiral-driven dynamo, produce protoplanets of the right mass and longevity.

    • Hongping Deng
    • Lucio Mayer
    • Ravit Helled
  • Sticking coefficients quantify the readiness of gas molecules to freeze onto the surface of dust grains. Here, laboratory measurements of the sticking coefficients of water and carbon dioxide onto realistic bare and icy dust grain analogues provide key data for the study of snowlines in protoplanetary disks, for example.

    • C. Laffon
    • D. Ferry
    • P. Parent
  • Detections of lithium (and in one case, potassium) in the atmospheres of four old white dwarfs suggest that they have accreted fragments of planets; specifically, planetary crusts. One white dwarf evolved from an intermediate-mass progenitor, indicating that rocky planets form even around short-lived B-type stars.

    • Mark A. Hollands
    • Pier-Emmanuel Tremblay
    • Nicola Pietro Gentile-Fusillo
  • Gamma-ray emission up to and above 100 TeV is detected from the supernova remnant G106.3+2.7. The emission above 10 TeV is associated with a molecular cloud rather than the pulsar PSR J2229+6114, favouring a hadronic origin via the π0 decay caused by accelerated relativistic protons.

    • M. Amenomori
    • Y. W. Bao
    • X. X. Zhou
  • Three-dimensional hydrodynamic simulations show that head-on galaxy collisions can suppress black hole fuelling by stripping the torus-shaped gas surrounding the massive black hole. Galaxy collisions could therefore either switch off or turn on nuclear activity, depending on the collision orbit.

    • Yohei Miki
    • Masao Mori
    • Toshihiro Kawaguchi
  • The protocluster LAGER-z7OD1 is discovered at a redshift of 6.93, identified by an overdensity of 6 times the average galaxy density and 16 spectroscopically confirmed members. It shows an elongated shape, indicative of a past merger, and its intergalactic medium is almost fully ionized.

    • Weida Hu
    • Junxian Wang
    • XianZhong Zheng
  • A delayed radio flare six months after an optically discovered tidal disruption event, followed by a second and brighter flare, years later, may potentially be due to the delayed ejection of an outflow following a transition in accretion states.

    • A. Horesh
    • S. B. Cenko
    • I. Arcavi
  • Modelling of Mead Basin, the largest impact feature on Venus, shows that it could only have got its shape, with the two ring faults at the correct position, if Venus were in a stagnant lid regime at the time of Mead Basin formation, between 0.3 and 1 billion years ago.

    • E. Bjonnes
    • B. C. Johnson
    • A. J. Evans
  • The tidal disruption event AT2019dsg is probably associated with a high-energy neutrino, suggesting that such events can contribute to the cosmic neutrino flux. The electromagnetic emission is explained in terms of a central engine, a photosphere and an extended synchrotron-emitting outflow.

    • Robert Stein
    • Sjoert van Velzen
    • Yuhan Yao
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Mission Control

  • Two novel imaging polarimeters are being installed on two 1-m-class telescopes in order to examine dust foregrounds in cosmic microwave background studies as part of the PASIPHAE survey.

    • A. Ramaprakash
    • A. C. S. Readhead
    • K. Tassis
    Mission Control
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Amendments & Corrections

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