High-energy astrophysics

  • Article
    | Open Access

    Evolution of accretion disk and corona during outbursts in black hole binary systems is still unclear. Here, the authors show spectral analysis of MAXI J1820+070 and propose a scenario of a dynamical corona to explain the evolution of the reflection fraction observed by Insight-HXMT.

    • Bei You
    • , Yuoli Tuo
    •  & Yue Zhu
  • Article
    | Open Access

    The discrepancy between the optical and X-ray properties of tidal disruption events (TDE) is an unresolved issue. Here, the authors show delayed X-ray brightening after the optical flare in TDE OGLE16aaa followed by several flux dips during the decay phase that could be explained by the presence of supermassive black hole binary or patchy obscuration.

    • Xinwen Shu
    • , Wenjie Zhang
    •  & Tinggui Wang
  • Article
    | Open Access

    The location of energy dissipation in powerful extragalactic jets is currently unknown. Here, the authors show that the more distant molecular torus is the dominant location for powerful jets using a diagnostic called the seed factor which is dependent only on observable quantities.

    • Adam Leah W. Harvey
    • , Markos Georganopoulos
    •  & Eileen T. Meyer
  • Article
    | Open Access

    Blazars show variable non-thermal emission across the electromagnetic spectrum from radio waves to gamma rays. Here, the authors show blazar 3C 279 reveals a characteristic peak-in-peak variability pattern on time scales of minutes if particle acceleration is due to relativistic magnetic reconnection.

    • A. Shukla
    •  & K. Mannheim
  • Article
    | Open Access

    Kilonovae observations can be used to out constraints on the Hubble constant (H0). Here, the authors show H0 measurements by combining light curves of four short gamma-ray burts with GW170817 are about a factor of 2-3 more precise than the standard-siren measurements using only gravitational-waves.

    • Michael W. Coughlin
    • , Sarah Antier
    •  & Nandita Khetan
  • Article
    | Open Access

    Independently measuring the tidal deformability and the fundamental oscillation mode (fmode) frequency enables tests of gravity and the nature of compact binaries. Here, the authors constrain the f-mode frequencies of the companions of GW170817 from direct measurements, demonstrating gravitational wave asteroseismology with binary inspiral signals alone.

    • Geraint Pratten
    • , Patricia Schmidt
    •  & Tanja Hinderer
  • Article
    | Open Access

    High redshift blazars are efficient probes of supermassive black holes and their environment in the early Universe. Here the authors show measurements of polarised emission and proper motion in the blazar J0906+6930 (redshift of 5.47) characterised by a nascent jet embedded in and interacting with a dense medium.

    • Tao An
    • , Prashanth Mohan
    •  & Zhenya Zheng
  • Article
    | Open Access

    Yonetoku relation provides a diagnostic for the radiation mechanism in the prompt phase of gamma-ray burst (GRB) emission. Here, Ito et al. show the reproduction of this relation in 3D hydrodynamical simulations followed by radiative transfer calculations, which suggest the photospheric emission is the dominant component in the prompt phase of GRBs.

    • Hirotaka Ito
    • , Jin Matsumoto
    •  & Daisuke Yonetoku
  • Article
    | Open Access

    PKS 2247–131 is an active galaxy that has been emitting gamma-ray flares since October 2016. Here, the authors used data obtained with the Fermi Gamma-ray Space Telescope to find that PKS 2247–131 presents a relatively short, month-like flux oscillation at gamma-ray energies of 0.1–300 GeV.

    • Jianeng Zhou
    • , Zhongxiang Wang
    •  & Jujia Zhang
  • Article
    | Open Access

    A faint gamma-ray burst (GRB 170817A) has been recently detected in coincidence with the gravitational wave (GW) event GW 170817. Here, the authors report that another faint short GRB at a cosmological distance (GRB150101B) and its late time emission are analogous to the neutron star merger event GRB 170817A.

    • E. Troja
    • , G. Ryan
    •  & S. Veilleux
  • Article
    | Open Access

    The IceCube Neutrino Observatory has been recording a flux of high-energy cosmic neutrinos since 2013. Here, the authors investigate the possibility of increasing its sensitivity by implementing wavelength shifting optics within IceCube’s drill holes.

    • Imre Bartos
    • , Zsuzsa Marka
    •  & Szabolcs Marka
  • Article
    | Open Access

    A short-duration gamma-ray burst was detected along with a double neutron start merger gravitational wave by LIGO-Virgo on August 17th 2017. Here, the authors show that the fluence and spectral peak energy of this event fall into the lower portion of the distribution of known short-duration gamma-ray bursts.

    • B.-B. Zhang
    • , B. Zhang
    •  & E.-W. Liang
  • Article
    | Open Access

    White-light flares are rare solar events entailing emission in the optical continuum. Here, the authors report a nearly circular white-light flare observed on March 10th 2015 that contains simultaneously both impulsive and gradual white-light kernels.

    • Q. Hao
    • , K. Yang
    •  & Z. Li
  • Article
    | Open Access

    Winged radio galaxies possess wing features detectable at radio wavelengths, yet the physical interpretation of such extragalactic radio sources remains elusive. Here, the authors report the observation of a downsized Z-shaped radio emission from the Galactic microquasar GRS 1758-258, shedding light on the formation of wings in radio galaxies given its strongly  reminiscent winged morphology.

    • Josep Martí
    • , Pedro L. Luque-Escamilla
    •  & Josep M. Paredes
  • Article
    | Open Access

    14C can be absorbed by trees as a result of the interaction of cosmic rays produced by high-energy phenomena with the Earth’s atmosphere. Here, the authors observe a rapid increase of 14C in an ancient buried tree from BC 3372 to BC 3371, and suggest that it could originate from a large solar proton event.

    • F. Y. Wang
    • , H. Yu
    •  & K. S. Cheng
  • Article
    | Open Access

    Advanced LIGO has detected gravitational waves from two binary black hole mergers, plus a merger candidate. Here the authors use the COMPAS code to show that all three events can be explained by a single evolutionary channel via a common envelope phase, and characterize the progenitor metallicity and masses.

    • Simon Stevenson
    • , Alejandro Vigna-Gómez
    •  & Selma E. de Mink
  • Article
    | Open Access

    A macronova is a clear signature that a short gamma-ray burst has been emitted by a compact-binary merger, but evidence of these events is so far scarce. Here, the authors report signs of a macronova in the optical afterglow of GRB050709, and find similar evidence in other three short bursts.

    • Zhi-Ping Jin
    • , Kenta Hotokezaka
    •  & Tsvi Piran
  • Article
    | Open Access

    Natural spikes in radiocarbon have been identified at AD 774/5 and 993/4 and attributed to exceptional cosmic-ray events, although the cause remains uncertain. Here, the authors analyse records recovered from ice cores and suggest these spikes originated from extreme solar particle events.

    • Florian Mekhaldi
    • , Raimund Muscheler
    •  & Thomas E. Woodruff
  • Article |

    Optical light from many stars is known to pulsate and degenerate objects, like neutron stars, are known to emit pulses of X-rays, but X-ray pulsations have yet to be associated with non-degenerate objects. Here, Oskinova et al. find X-ray pulsations from a non-degenerate object: the massive B-type star ξ1CMa.

    • Lidia M. Oskinova
    • , Yael Nazé
    •  & Wolf-Rainer Hamann
  • Article |

    The origin of the highest energy cosmic rays is still unknown. Here, Chakraborti and colleagues show that a recently discovered sub-population of type Ibc supernovae with mildly relativistic outflows can satisfy all required characteristics for an ultra-high-energy cosmic ray source.

    • S. Chakraborti
    • , A. Ray
    •  & P. Chandra