DETERMINATION OF SUPPLIES CHARACTERISTICS OF THE DEVICE FOR ABRASIVE WATER-JET MACHINING

The technique of experimental determination of the consumption characteristics of the apparatus for jet hydroabrasive processing is considered. Results are presented for determining the costs of abrasive slurry and compressed air through a jet apparatus

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

High Energy Astrophysic

The First Distant X-ray Quasars (z ~ 4) among the Sources Discovered by the eROSITA Telescope of the SRG Orbital Observatory during a Deep Lockman Hole Survey

© 2020, Pleiades Publishing, Inc. Abstract: During a deep extragalactic Lockman Hole sky survey with an area of 18.5 sq. deg, which was conducted when the SRG observatory was flying to the Lagrange point L2, the eROSITA telescope detected ~7000 X-ray sources. These objects were then provisionally identified and classified using the publicly accessible data of optical and infrared sky surveys by the SRGz machine learning system developed for this purpose at the Space Research Institute of the Russian Academy of Sciences. As a result, a number of new candidates for distant quasars (z ~ 4) have been selected. The spectroscopic observations of the first two candidates from this list carried out with the 1.6-m AZT-33IK telescope of the Sayan Solar Observatory have confirmed that these objects are actually distant quasars at redshifts 3.878 and 4.116 and are characterized by a high X-ray luminosity ~1045 erg s-1 (2–10 keV). The results obtained allow one to count on the detection of a large number of distant quasars during a four-year all-sky survey of the SRG observatory begun in December 2019

Optical Spectroscopy of SRG/eROSITA Objects with 2.5-m Telescope at the Caucasus Mountain Observatory of the SAI MSU

© 2020, Pleiades Publishing, Inc. Based on observations with the new transient double-beam spectrograph (TDS) at the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU, we have determined the types and found the redshifts for six new X-ray sources (four quasars and two galaxy clusters) detected by the SRG space observatory during the Lockman Hole observations at the eROSITA performance verification phase. We show that the TDS allows the spectra of objects ~20m to be taken in 2 h of observations with a signal-tonoise ratio higher than 5 and a resolution R ~1500. The types and redshifts of the objects determined from our spectroscopic observations agree well with the predictions based on photometric data using the SRGz automatic classification system