Supernova explosions of runaway stars and young neutron stars above the Galactic plane

¹ Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova, Via Marzolo 8, 35121, Padova, Italy
² Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetsky prospekt 13, 119234, Moscow, Russia
³ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey, RH5 6NT, UK

^⋆ Corresponding author.

Received: 17 April 2025
Accepted: 11 July 2025

Abstract

Context. Several supernova remnants and young neutron stars were recently discovered relatively high above the Galactic plane. Understanding their origin will provide key insights into the properties of the Galactic halo. One possibility is that they originated from runaway OB stars born in the Galactic disk.

Aims. We aim to determine the spatial distribution of supernova explosions from runaway OB stars and to assess whether this model can explain certain observed neutron stars.

Methods. We mapped the distribution of supernova events produced by runaway OB stars by incorporating their birth rate, initial spatial distribution, lifetime, ejection mechanisms, and velocity distributions. By tracking their motion in the Galactic potential, we determined their final distribution right before the explosion.

Results. We show that the neutron star Calvera, which is found at z ≈ 2.2 kpc, could have originated from a runaway OB star. In addition, we compared the probabilities of finding a supernova remnant originating from Type Ia and core-collapse supernovae high above the Galactic plane, finding that supernova remnants related to core-collapse supernovae outnumber those related to Type Ia supernovae.