The progenitors of calcium-rich transients are not formed in situ

Abstract

We present deep VLT and HST observations of the nearest examples of calcium-rich 'gap' transients -- rapidly evolving transient events, with a luminosity intermediate between novae and supernovae. These sources are frequently found at large galactocentric offsets, and their progenitors remain mysterious. Our observations find no convincing underlying quiescent sources coincident with the locations of these transients, allowing us to rule out a number of potential progenitor systems. The presence of surviving massive-star binary companions (or other cluster members) are ruled out, providing an independent rejection of a massive star origin for these events. Dwarf satellite galaxies are disfavoured unless one invokes as yet unknown conditions that would be extremely favourable for their production in the lowest mass systems. Our limits also probe the majority of the globular cluster luminosity function, ruling out the presence of an underlying globular cluster population at high significance, and thus the possibility that they are created via dynamical interactions in dense globular cluster cores. Given the lack of underlying systems, previous progenitor suggestions have difficulty reproducing the remote locations of these transients, even when considering solely halo-borne progenitors. Our preferred scenario is that calcium-rich transients are high velocity, kicked systems, exploding at large distances from their natal site. Coupled with a long-lived progenitor system post-kick, this naturally explains the lack of association these transients have with their host stellar light, and the extreme host-offsets exhibited. Neutron star -- white dwarf mergers may be a promising progenitor system in this scenario.

Accepted for publication in MNRAS, 11 pages, 9 figures

References in corpus (15)

• Binary interaction dominates the evolution of massive stars
• Physical Properties of Wolf-Rayet Stars
• Long gamma-ray bursts and core-collapse supernovae have different environments
• The effect of massive binaries on stellar populations and supernova progenitors
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• Long Gamma-Ray Bursts and Type Ic Core Collapse Supernovae Have Similar Locations in Hosts
• Fallback Supernovae: A Possible Origin of Peculiar Supernovae with Extremely Low Explosion Energies
• Formation and evolution of compact binaries in globular clusters: I.Binaries with white dwarfs
• ACS photometry of extended, luminous globular clusters in the outskirts of M31
• A new type of long gamma--ray burst
• A deeper search for the progenitor of the Type Ic Supernova 2002ap
• The radial distribution of type Ia supernovae in early-type galaxies: implications for progenitor scenarios
• Origin of the Galactic 511 keV emission from positrons produced in irregular supernovae
• Visible and dark matter in M31 - I. Properties of stellar components

Cited by in corpus (10)

• The optical afterglow of GW170817 at one year post-merger
• Gamma-ray burst progenitors
• Mass transfer in white dwarf-neutron star binaries
• Theoretical Models of Optical Transients. I. A Broad Exploration of the Duration-Luminosity Phase Space
• Two New Calcium-Rich Gap Transients in Group and Cluster Environments
• Statistical studies of supernova environments
• SN 2019ehk: A Double-Peaked Ca-rich Transient with Luminous X-ray Emission and Shock-Ionized Spectral Features
• Calcium-Rich Gap Transients: Tidal Detonations of White Dwarfs?
• iPTF15eqv: Multi-wavelength Exposé of a Peculiar Calcium-rich Transient
• OGLE-2013-SN-079: a lonely supernova consistent with a helium shell detonation