Correction to: High precision particle astrophysics as a new window on the universe with an Antimatter Large Acceptance Detector In Orbit (ALADInO)

A Correction to this paper has been published: 10.1007/s10686-021-09771-3

Black hole factory: A review of double-null formalism

In this review paper, we comprehensively summarize numerical applications of double-null formalism for studying dynamics within the theory of gravity. By using the double-null coordinates, we can investigate dynamical black holes and gravitational phenomena within spherical symmetry, including gravitational collapse, formation of horizons and singularities, as well as evaporations. This formalism can be extended to generic situations, where we can change dimensions, topologies, the gravity sector, as well as the matter sector. We also discuss its possible implications for black hole physics and particle astrophysics. This strong numerical tool will have lots of future applications for various research areas including general relativity, string theory and various approaches to quantum gravity.

Future ground arrays for ultrahigh-energy cosmic rays: recent updates and perspectives

The origin and nature of ultrahigh-energy cosmic rays (UHECRs) are one of the most intriguing mysteries in particle astrophysics and astronomy. The two largest observatories, the Pierre Auger Observatory and the Telescope Array Experiment, are steadily observing UHECRs in both hemispheres in order to better understand their origin and associated acceleration mechanisms at the highest energies. We highlight their latest results including on-going upgrades, AugerPrime and TA×4, and then address the requirements for a next-generation observatory. We share recent updates and perspectives for a future ground array of fluorescence detectors, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays with an unprecedented aperture.