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Li et al. report new simultaneous XMM-Newton and Australia Telescope
Compact Array observations of 3FGL J0427.9−6704, a candidate member of
the enigmatic class of transitional millisecond pulsars. Unlike the
few well-studied transitional millisecond pulsars, which spend most of
their disk state in a characteristic high or low accretion mode with
occasional flares, 3FGL J0427.9−6704 stayed in the flare mode for the
entire ~20 hour X-ray observation. The X-ray and optical light curves
are dominated by strong flares on time-scales of 10~100 sec. In
addition, each light curve shows three eclipses, at the predicted
times. In contrast, the figure above shows the ATCA 5.5 and 9.0 GHz
light curve. The radio continuum data show only modest variability but
no clear flares, and there is no evidence that the radio emission is
eclipsed (the greyed time-ranges), which is consistent with the
presence of a steady radio outflow or jet. The simultaneous
radio/X-ray luminosity ratio of 3FGL J0427.9−6704 is higher than any
known transitional millisecond pulsars and comparable to that of
stellar-mass black holes of the same X-ray luminosity, providing
additional evidence that some neutron stars can be as radio-loud as
black holes.
The paper has been published in the Astrophysical Journal.
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