This website requires JavaScript.

Multi-Wavelength Observations Of A New Redback Millisecond Pulsar 4FGL J1910.7-5320

Ka-Yui AuJay StraderSamuel J. Swihart ...+8 Kwan-Lok Li
Dec 2022
We present the study of multi-wavelength observations of an unidentifiedFermi Large Area Telescope (LAT) source, 4FGL J1910.7-5320, a new candidateredback millisecond pulsar binary. In the 4FGL 95% error region of 4FGLJ1910.7-5320, we find a possible binary with a 8.36-hr orbital period from theCatalina Real-Time Transient Survey (CRTS), confirmed by optical spectroscopyusing the SOAR telescope. This optical source was recently independentlydiscovered as a redback pulsar by the TRAPUM project, confirming ourprediction. We fit the optical spectral energy distributions of 4FGLJ1910.7-5320 with a blackbody model, inferring a maximum distance of 4.1 kpc byassuming that the companion fills its Roche-lobe with a radius of R = 0.7R_sun.Using a 12.6 ks Chandra X-ray observation, we identified an X-ray counterpartfor 4FGL J1910.7-5320, with a spectrum that can be described by an absorbedpower-law with a photon index of 1.0+/-0.4. The spectrally hard X-ray emissionshows tentative evidence for orbital variability. Using more than 12 years ofFermi-LAT data, we refined the position of the {\gamma}-ray source, and theoptical candidate still lies within the 68% positional error circle. Inaddition to 4FGL J1910.7-5320, we find a variable optical source with aperiodic signal of 4.28-hr inside the 4FGL catalog 95% error region of anotherunidentified Fermi source, 4FGL J2029.5-4237. However, the {\gamma}-ray sourcedoes not have a significant X-ray counterpart in a 11.7 ks Chandra observation,with a 3-{\sigma} flux upper limit of 2.4*10^-14 erg cm^-2 s^-1 (0.3-7 keV).Moreover, the optical source is outside our updated Fermi-LAT 95% error circle.These observational facts all suggest that this new redback millisecond pulsarpowers the {\gamma}-ray source 4FGL J1910.7-5320 while 4FGL J2029.5-4237 isunlikely the {\gamma}-ray counterpart to the 4.28-hr variable.