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 ART-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 similar to 250 '' in radius and a beta-model with a characteristic size similar to 480 ''. 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 (N-H similar or equal to 0.7 x 10(22) cm(-2)) 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 spectrumis considerably softer (a power-law index similar or equal to 2.8) than the pulsar spectrum(a power-law index similar or equal to 0.9), consistent with the predictions of theoretical models for the X-ray scattering by dust.