We discuss properties of the ultra-luminous X -ray source in the galaxy M82 , NuSTAR J095551+6940.8 , containing an accreting neutron star .
The neutron star has surface magnetic field B _ { NS } \approx 1.4 \times 10 ^ { 13 } { G } and experiences accretion rate of 9 \times 10 ^ { -7 } M _ { \odot } { yr } ^ { -1 } .
The magnetospheric radius , close to the corotation radius , is \sim 2 \times 10 ^ { 8 } cm .
The accretion torque on the neutron star is reduce well below what is expected in a simple magnetospheric accretion due to effective penetration of the stellar magnetic field into the disk beyond the corotation radius .
As a result , the radiative force of the surface emission does not lead to strong coronal wind , but pushes plasma along magnetic field lines towards the equatorial disk .
The neutron star is nearly an orthogonal rotator , with the angle between the rotation axis and the magnetic moment \geq 80 degrees .
Accretion occurs through optically thick – geometrically thin and flat accretion “ curtain ” , which cuts across the polar cap .
High radiation pressure from the neutron star surface is nevertheless smaller than that the ram pressure of the accreting material flowing through the curtain , and thus fails to stop the accretion .
At distances below few stellar radii the magnetic suppression of the scattering cross-section becomes important .
The X -ray luminosity ( pulsed and persistent components ) comes both from the neutron star surface as a hard X -ray component and as a soft component from reprocessing by the accretion disk .