2021ApJ...923....3J

3FGL J1544.6-1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs-PSR J1023+0038, IGR J18245-2452, and XSS J12270-4859-3FGL J1544.6-1125 shows γ-ray emission and discrete X-ray "low" and "high" modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission-possibly originating from a compact, self-absorbed jet, the "propellering" of accretion material, and/or pulsar moding. 3FGL J1544.6-1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6-1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 µJy down to <=15 µJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L_5 GHz_ = (2.17 ± 0.17) x 10²⁷ erg s^–1 for a quasi-simultaneous X-ray luminosity L_2-10 keV_ = (4.32 ± 0.23) x 10³³ erg s^–1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6-1125 is a tMSP showing similar phenomenology to PSR J1023+0038.