FAST’s Discovery of a New Millisecond Pulsar (MSP) toward the Fermi-LAT unassociated source 3FGL J0318.1+0252

ATel #11584; Pei Wang, Di Li, Weiwei Zhu, Chengmin Zhang, Jun Yan (National Astronomical Observatories, Chinese Academy of Sciences), Xian Hou (YunNan Observatories, Chinese Academy of Sciences), Colin J. Clark (Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester), Pablo M. Saz Parkinson (Department of Physics and Laboratory for Space Research, University of Hong Kong & Santa Cruz Institute for Particle Physics), Peter F. Michelson (Stanford University), Elizabeth C. Ferrara (UMCP/CRESST/GSFC), David J. Thompson, (NASA/GSFC), David A. Smith (Universite ? Bordeaux 1, CNRS/IN2P3/CENBG), Paul S. Ray, Matthew Kerr (Space Science Division, Naval Research Laboratory), Zhiqiang Shen (Shanghai Astronomical Observatory), Na Wang (Xinjiang Astronomical Observatory), on behalf of FAST and the Fermi-LAT Collaboration. 
on 28 Apr 2018; 04:43 UT
Credential Certification: Di Li (dili@nao.cas.cn)

Tweet

The Five hundred-meter Aperture Spherical radio Telescope (FAST), operated by the National Astronomical Observatories, Chinese Academy of Sciences, has discovered a radio millisecond pulsar (MSP) coincident with the unassociated gamma-ray source 3FGL J0318.1+0252 (Acero et al. 2015 ApJS, 218, 23), also known as FL8Y J0318.2+0254 in the recently released Fermi Large Area Telescope (LAT) 8-year Point Source List (FL8Y). Following the discovery of the radio pulsar, gamma-ray pulsations were detected in 9.6 years of Fermi-LAT data by performing a semi-blind search around the spin period from the radio discovery, searching over the full FL8Y localization region and over a range of spin-down rates typical for MSPs. The newly detected pulsar is named PSR J0318+0253 based on the refined position from gamma-ray analysis. J0318+0253 has a precise position of RA(J2000)=03:18:15.54, Dec(J2000)=+02:53:01.5, a period of 5.19 milliseconds, a dispersion measure of 26 pc cm^-3 that corresponds to a distance of about 1.3 kpc based on Yao et al. (2016), and no detectable acceleration.

Previous radio observations of 3FGL J0318.1+0252, including three different epochs with Arecibo with a typical individual integration times of 15 minutes in June 2013, did not detect the MSP. On 27 Feb. 2018, in a one-hour tracking observation with the FAST ultra-wide band receiver, the radio pulses toward 3FGL J0318.1+0252 were detected with 512 MHz bandwidth centered around 560 MHz. We estimated the pulsar’s flux density to be ~100 micro-Jy, corresponding to less than 15 micro-Jy in L-band assuming a canonical spectral index of 2.1, making this potentially one of the faintest MSPs discovered in the radio band. The detection and timing of gamma-ray pulsations confirms that it is an isolated pulsar. 

 No X-ray counterpart is detected at the pulsar position. An analysis of 3.4 ks of Swift XRT observations of the region resulted in an unabsorbed flux upper limit in the 0.3-10 keV energy range of 2.8e-13 erg cm^-2 s^-1, for an assumed power-law spectrum of index 2 and an absorption column N(H) = 8 × 10^20 cm^-2 in the direction of the MSP. Deeper multi-wavelength follow-up observations are strongly encouraged.

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. FAST will be under commissioning until it reaches the designed specifications and becomes a Chinese national facility. This discovery is part of the pilot program for the planned Commensal Radio Astronomy FAST Survey (CRAFTS—arxiv:1802.03709) and also the first result from a collaboration between the FAST team and the Fermi-LAT Collaboration outlined in an MoU signed by both teams. 

FAST's First MSP