Volume 1 Issue 12 December 2017

Volume 1 Issue 12

Optical jet lag

An artist's impression of a black hole accreting matter from a companion star (red) launches a jet of hot plasma (purple), funnelled by swirling magnetic fields. Measurements of a lag between optical and X-ray emission reveal the characteristic elevation where the jet becomes optically thin (white), giving insight into the physics of plasma acceleration.

See Gandhi et al. 1, 859–864 (2017)

Image: NASA/JPL-Caltech/Robert Hurt. Cover Design: Alex Wing

Editorial

  • Editorial |

    What started 50 years ago as a ‘smudge’ on paper has flourished into a fundamental field of astrophysics replete with unexpected applications and exciting discoveries. To celebrate the discovery of pulsars, we look at the past, present and future of pulsar astrophysics.

Correspondence

Comment & Opinion

  • Comment |

    Pulsars — fast-spinning neutron stars — are precision clocks provided by nature. Finding pulsars in the Galactic Centre orbiting Sagittarius A*, the closest supermassive black hole to the Earth, will offer unprecedented opportunities to test general relativity and its alternatives.

    • Kuo Liu
    •  & Ralph Eatough

Books & Arts

Research Highlights

News & Views

  • News & Views |

    More than 20 GW of power are necessary to balance the heat emitted by Enceladus and avoid the freezing of its internal ocean. A very porous core undergoing tidal heating can generate the required power to maintain a liquid ocean and drive hydrothermal activity.

    • Francis Nimmo
  • News & Views |

    The detection of bright, rapid optical pulsations from pulsar PSR J1023+0038 have provided a surprise for researchers working on neutron stars. This discovery poses more questions than it answers and will spur on future work and instrumentation.

    • Craig O. Heinke
  • News & Views |

    Black holes absorb everything and emit nothing, yet relativistic jets of plasma are observed to emanate from systems hosting accreting black holes. We now know exactly how far from the black hole these processes take place.

    • Nikolaos D. Kylafis

Reviews

Research

  • Letter |

    Tidal forcing within a very porous (unconsolidated) core can generate enough energy to drive all the observed global features of Enceladus. This activity can be sustained up to several billion years.

    • Gaël Choblet
    • , Gabriel Tobie
    • , Christophe Sotin
    • , Marie Běhounková
    • , Ondřej Čadek
    • , Frank Postberg
    •  & Ondřej Souček
  • Letter |

    The atmosphere of evolved star W Hya has been resolved with ALMA and shown to be shock heated. These observations provide important empirical constraints for the understanding of circumstellar structure, convection, chemistry and pulsation.

    • Wouter Vlemmings
    • , Theo Khouri
    • , Eamon O’Gorman
    • , Elvire De Beck
    • , Elizabeth Humphreys
    • , Boy Lankhaar
    • , Matthias Maercker
    • , Hans Olofsson
    • , Sofia Ramstedt
    • , Daniel Tafoya
    •  & Aki Takigawa
  • Letter |

    Optical pulsations from a millisecond pulsar that had transitioned from a rotationally powered regime to an accretion disk state have been detected. The optical emission is likely to be due to electron synchrotron emission in a rotation-powered magnetosphere.

    • F. Ambrosino
    • , A. Papitto
    • , L. Stella
    • , F. Meddi
    • , P. Cretaro
    • , L. Burderi
    • , T. Di Salvo
    • , G. L. Israel
    • , A. Ghedina
    • , L. Di Fabrizio
    •  & L. Riverol
  • Letter |

    A delay between rapid optical and X-ray flux variations from an accreting black-hole binary is reported together with a brightening radio jet, indicating a characteristic elevation of the radiative jet base of 0.1 light-seconds above the black hole.

    • P. Gandhi
    • , M. Bachetti
    • , V. S. Dhillon
    • , R. P. Fender
    • , L. K. Hardy
    • , F. A. Harrison
    • , S. P. Littlefair
    • , J. Malzac
    • , S. Markoff
    • , T. R. Marsh
    • , K. Mooley
    • , D. Stern
    • , J. A. Tomsick
    • , D. J. Walton
    • , P. Casella
    • , F. Vincentelli
    • , D. Altamirano
    • , J. Casares
    • , C. Ceccobello
    • , P. A. Charles
    • , C. Ferrigno
    • , R. I. Hynes
    • , C. Knigge
    • , E. Kuulkers
    • , M. Pahari
    • , F. Rahoui
    • , D. M. Russell
    •  & A. W. Shaw
  • Letter |

    The discovery of the most energetic transient event to date is reported. Its spectroscopic properties and temporal evolution imply it is powered by shock interaction between expanding material and large quantities of surrounding dense matter.

    • E. Kankare
    • , R. Kotak
    • , S. Mattila
    • , P. Lundqvist
    • , M. J. Ward
    • , M. Fraser
    • , A. Lawrence
    • , S. J. Smartt
    • , W. P. S. Meikle
    • , A. Bruce
    • , J. Harmanen
    • , S. J. Hutton
    • , C. Inserra
    • , T. Kangas
    • , A. Pastorello
    • , T. Reynolds
    • , C. Romero-Cañizales
    • , K. W. Smith
    • , S. Valenti
    • , K. C. Chambers
    • , K. W. Hodapp
    • , M. E. Huber
    • , N. Kaiser
    • , R.-P. Kudritzki
    • , E. A. Magnier
    • , J. L. Tonry
    • , R. J. Wainscoat
    •  & C. Waters
  • Letter |

    Saturn’s proton radiation belts are quite an isolated system and can be used as a laboratory for endogenous impacts on planetary radiation belts. Their evolution over a solar cycle shows variations associated with changes in magnetospheric radial diffusion.

    • P. Kollmann
    • , E. Roussos
    • , A. Kotova
    • , C. Paranicas
    •  & N. Krupp
  • Article |

    The inner four planets of the TRAPPIST-1 system experienced induction heating due to magnetic interaction with their host star. This led them to experience increased volcanic activity, outgassing and potentially a subsurface magma ocean.

    • K. G. Kislyakova
    • , L. Noack
    • , C. P. Johnstone
    • , V. V. Zaitsev
    • , L. Fossati
    • , H. Lammer
    • , M. L. Khodachenko
    • , P. Odert
    •  & M. Güdel
  • Article |

    We calculate the continuous nanohertz gravitational-wave emission from individual supermassive black hole binaries and the gravitational-wave background they generate, which will be observable with pulsar timing arrays.

    • Chiara M. F. Mingarelli
    • , T. Joseph W. Lazio
    • , Alberto Sesana
    • , Jenny E. Greene
    • , Justin A. Ellis
    • , Chung-Pei Ma
    • , Steve Croft
    • , Sarah Burke-Spolaor
    •  & Stephen R. Taylor

Amendments & Corrections

Mission Control

  • Mission Control |

    Forty years ago, the two Voyager spacecraft left Earth to begin one of the most rewarding voyages of human discovery ever to have been undertaken. Project Scientist Ed Stone recounts his treasured moments from the mission.

    • Ed Stone