Surrounded by Spiders! New Black Widows and Redbacks in the Galactic Field

TL;DR

This paper reviews recent discoveries of eclipsing millisecond pulsar systems in the Galactic field, focusing on black widows and redbacks, and discusses their properties, models, and evolutionary implications.

Contribution

It provides a comprehensive overview of new black widow and redback pulsar systems, highlighting their multi-wavelength characteristics and evolutionary significance.

Findings

Many new systems discovered associated with Fermi sources

Redbacks likely represent transitional phases in binary evolution

Models of shock emission and mass transfer are discussed

Abstract

Over the last few years, the number of known eclipsing radio millisecond pulsar systems in the Galactic field has dramatically increased, with many being associated with Fermi gamma-ray sources. All are in tight binaries (orbital period < 24 hr) with many being classical "black widows" which have very low mass companions (companion mass Mc << 0.1 Msol) but some are "redbacks" with low mass (Mc ~ 0.2 - 0.4Msol) companions which are probably non-degenerate. These latter are systems where the mass transfer process may have only temporarily halted, and so are transitional systems between low mass X-ray binaries and ordinary binary millisecond pulsars. Here we review the new discoveries and their multi-wavelength properties, and briefly discuss models of shock emission, mass determinations, and evolutionary scenarios.