A STATE CHANGE IN THE MISSING LINK BINARY PULSAR SYSTEM PSR J1023+0038

• Published in: The Astrophysical journal Vol. 790; no. 1; pp. 1 - 8
• Main Authors: Stappers, B W, Archibald, A M, Hessels, J W T, Bassa, C G, Bogdanov, S, Janssen, G H, Kaspi, V M, Lyne, A G, Patruno, A, Tendulkar, S, Hill, A B, Glanzman, T
• Format: Journal Article
• Language: English
• Published: United States Institute of Physics (IOP) 01.07.2014
• Subjects: Accretion disks; ASTRONOMY AND ASTROPHYSICS; Binary stars; Binary systems (materials); Flux; Pulsars; Pulsation; Radio; Transformations
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/790/1/39

We present radio and gamma -ray observations, which, along with concurrent X-ray observations, reveal that the binary millisecond pulsar (MSP)/low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000 MHz have now become undetectable. Concurrent with this radio disappearance, the gamma -ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditions to create the gamma -ray increase. This system is the first example of a compact, low-mass binary which has shown significant state changes accompanied by large changes in gamma -ray flux; it will continue to provide an exceptional test bed for better understanding the formation of MSPs as well as accretion onto neutron stars in general.