Nordita Astrophysics Seminars

Hunting for the missing spiders and transformers

by Albert Kong (Institute of Astronomy, National Tsing Hua University, Taiwan)

Europe/Stockholm
Description
The evolutionary and formation of millisecond pulsars (MSPs) has long been a subject of inquiry, and one widely accepted version is that an old neutron star has been spun up to a spin period on the order of millisecond via accretion from a late-type companion which transferred mass and angular momentum to the pulsar. Once the accretion has stopped, the relativistic, strongly magnetized pulsar wind will possibly carry away the pulsar rotational energy and angular momentum, meanwhile ablate and eventually evaporate its companion. It is generally believed that radio MSPs can only be turned on when the mass transfer from the companion star is extremely low. However, the observational evidence of such transition has not been found until recently. In this talk, I will review recent discoveries of "transformer" MSPs that switch between low-mass X-ray binaries and radio MSPs. I will also discuss how multi-wavelength observations reveal a new population of black widow/redback MSPs that provides new insight into MSP's emission mechanisms and the physics of compact objects.