X-ray Halo of the Pulsar 4U 1538–52 from SRG Data

We present the first results of the SRG observation of the pulsar 4U 1538–52 based on ARC-XC and eROSITA data. An extended emission in the form of a halo is detected around the source in the 0.5–8 keV energy band. Our simulation has shown that its surface brightness distribution can be described by a two-component model composed of a flat disk in radius and a -model with a characteristic size . We have constructed a broadband spectrum of 4U 1538–52 in the energy range 0.5–30 keV, which can be fitted by a weakly absorbed ( cm ) power law with a high-energy cutoff. In addition, iron emission lines are detected in the pulsar spectrum at 6–7 keV. We show that the observed halo spectrum is considerably softer (a power-law index ) than the pulsar spectrum (a power-law index ), consistent with the predictions of theoretical models for the X-ray scattering by dust.