The eROSITA X-ray telescope on SRG

Abstract

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 13, 2019, from the Baikonour cosmodrome. After the commissioning of the instrument and a subsequent calibration and performance verification phase, eROSITA started a survey of the entire sky on December 13, 2019. By the end of 2023, eight complete scans of the celestial sphere will have been performed, each lasting six months. At the end of this program, the eROSITA all-sky survey in the soft X-ray band (0.2-2.3 keV) will be about 25 times more sensitive than the ROSAT All-Sky Survey, while in the hard band (2.3-8 keV) it will provide the first ever true imaging survey of the sky. The eROSITA design driving science is the detection of large samples of galaxy clusters up to redshifts z > 1 in order to study the large-scale structure of the universe and test cosmological models including Dark Energy. In addition, eROSITA is expected to yield a sample of a few million AGNs, including obscured objects, revolutionizing our view of the evolution of supermassive black holes. The survey will also provide new insights into a wide range of astrophysical phenomena, including X-ray binaries, active stars, and diffuse emission within the Galaxy. Results from early observations, some of which are presented here, confirm that the performance of the instrument is able to fulfil its scientific promise. With this paper, we aim to give a concise description of the instrument, its performance as measured on ground, its operation in space, and also the first results from in-orbit measurements.

Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395

“…On July 13, 2019, eROSITA (extended ROentgen Survey with an Imaging Telescope Array) was successfully launched and made its way into an L2 halo orbit (Predehl et al 2020).…”

Fast flaring observed from XMMU J053108.3−690923 by eROSITA: a supergiant fast X-ray transient in the Large Magellanic Cloud

“…During the commissioning phase of eROSITA (Predehl et al 2020) SN 1987A was observed on 2019-09-15 (hereafter referred to as Obs. 1) with only the cameras from telescope modules 3 and 4 (TM3, TM4) observing the sky with XMMU J053108.3−690923 in the field of view.…”

“…The data were reduced with a pipeline based on the eROSITA Standard Analysis Software System (eSASS, Predehl et al 2020), which determines good time intervals, corrupted events and frames, and dead times, masks bad pixels, and applies pattern recognition and energy calibration. Finally, star-tracker and gyro data are used to assign celestial coordinates to each reconstructed X-ray photon.…”

The ROSAT Raster survey in the north ecliptic pole field

“…The ultimate goal of HEROES (see e.g. Songaila et al 2018) is to cover an area of 120 deg 2 around the NEP, where the eROSITA X-ray all-sky survey (Merloni et al 2012;Predehl et al 2020) will have some of its deepest coverage. This survey utilizes the wide-field capability of the Hyper Suprime-Cam instrument (HSC; Miyazaki et al 2012) on the Subaru 8.2 m telescope, as well as the MegaPrime/MegaCam and WIRCam instruments on the 3.6 m CFHT to map this large area.…”

“…Future missions will also have an important focus on the NEP. The eROSITA (Merloni et al 2012;Predehl et al 2020) and ART-XC (Pavlinsky et al 2018) telescopes on board of the recently launched Spektr-RG mission (Pavlinsky et al 2009) are currently producing an X-ray all-sky survey more than an order of magnitude deeper than ROSAT, which again will have particularly deep and wide coverage at the ecliptic poles (see Merloni et al 2020). The future NASA Medium Explorer mission Fig.…”