We report on combined INTEGRAL and XMM-Newton observations of the supergiant fast X-ray transient IGR J16418 - 4532 .
The observations targeted the X-ray eclipse region of IGR J16418 - 4532s orbit with continuous INTEGRAL observations across \sim 25 % of orbital phase and two quasi-simultaneous XMM-Newton observations of length 20 ks and 14 ks , occurring during , and just after the eclipse respectively .
An enhanced INTEGRAL emission history is provided with 19 previously unreported outbursts identified in the archival 18 - 60 keV data set .
The XMM-Newton eclipse observation showed prominent Fe-emission and a flux of 2.8 \times 10 ^ { -13 } erg cm ^ { -2 } s ^ { -1 } ( 0.5 - 10 keV ) .
Through the comparison of the detected eclipse and post eclipse flux , the supergiant mass loss rate through the stellar wind was determined as \dot { M } _ { w } = 2.3-3.8 \times 10 ^ { -7 } M _ { \odot } yr ^ { -1 } .
The post eclipse XMM-Newton observation showed a dynamic flux evolution with signatures of the X-ray pulsation , a period of flaring activity , structured n _ { H } variations and the first ever detection of an X-ray intensity dip , or ‘ off-state ’ , in a pulsating supergiant fast X-ray transient .
Consideration is given to the origin of the X-ray dip and we conclude that the most applicable of the current theories of X-ray dip generation is that of a transition between Compton cooling dominated and radiative cooling dominated subsonic accretion regimes within the ‘ quasi-spherical ’ model of wind accretion .
Under this interpretation , which requires additional confirmation , the neutron star in IGR J16418 - 4532 possesses a magnetic field of \sim 10 ^ { 14 } G , providing tentative observational evidence of a highly magnetised neutron star in a supergiant fast X-ray transient for the first time .
The implications of these results on the nature of IGR J16418 - 4532 itself and the wider SFXT class are discussed .