A New Predicted Class of Astrophysical Sources: White Dwarf Binary Mergers Poised for Discovery at The Vera Rubin Observatory

Astrophysicists are on the verge of a significant breakthrough, as recent research anticipates that the Vera Rubin Observatory, scheduled to begin operations in mid-2024, will be able to detect a new type of astrophysical source. The study predicts that the emission associated with mergers of white dwarf binaries, in wavelengths from infrared to ultraviolet, will be observed at an astonishing rate of up to a thousand per year! The results of this research, to be published in The Astrophysical Journal, were conducted by a researcher from the PPGCosmo/Cosmo-Ufes at Universidade Federal do Espírito Santo (UFES), Jaziel Goulart, in collaboration with Brazilian colleagues from the Instituto Nacional de Pesquisas Espaciais (INPE), the Universidade Tecnológica Federal do Paraná (UTFPR), as well as researchers from the International Center for Relativistic Astrophysics Network (ICRANet) and associates from the University of Ferrara and the Italian National Institute for Astrophysics (INAF).

The study indicates that binary white dwarf stars, in the cataclysm produced by their merger, radiate a distinctive "optical" transient about half a day after the merger process. The material ejected at a high speed of 1000 km/s with temperatures of 100,000 degrees generates a luminosity of 10 to 100 million times that of the Sun for a few hours. The rapid expansion, however, causes the material to cool quickly, which explains why their observation has so far escaped the eyes of telescopes. This astrophysical source displays observational characteristics that bridge the gap between nines and supernovas, with a luminosity and temporal evolution similar to kilonovae.

The most exciting result of the research is that, by putting together the expected population of these mergers and the characteristics of their emission, the researchers estimated that the Vera Rubin Observatory, equipped with cutting-edge instrumentation and a wide field of view, is ready to capture many of these events at a very high frequency of up to a thousand per year. If the observations meet predictions, these stellar mergers promise unprecedented insights into the processes that govern their birth and evolution. Scientists say detecting these optical transients will profoundly impact our knowledge of astrophysical phenomena linking massive white dwarfs and the formation of neutron stars and provide crucial information on the possible generation of Type Ia supernovae from binary white dwarf mergers.

As new wide-field facilities that follow the path of predecessors like the Palomar Transient Factory and the Zwicky Transient Facility, such as the Vera Rubin Observatory, prepare to begin their mission, the astronomical community eagerly awaits the dawn of this new era in the exploration of astrophysical optical transients.
The work to be published can be found at this link: https://arxiv.org/abs/2310.06655.

Artistic impression by NICOLE REINDL (CC BY 4.0)