The ART-XC telescope on board the SRG observatory

Abstract

ART-XC (Astronomical Roentgen Telescope -X-ray Concentrator) is the hard X-ray instrument with grazing incidence imaging optics on board the Spektr-Roentgen-Gamma (SRG) observatory. The SRG observatory is the flagship astrophysical mission of the Russian Federal Space Program, which was successively launched into orbit around the second Lagrangian point (L2) of the Earth-Sun system with a Proton rocket from the Baikonur cosmodrome on 13 July 2019. The ART-XC telescope will provide the first ever true imaging all-sky survey performed with grazing incidence optics in the 4-30 keV energy band and will obtain the deepest and sharpest map of the sky in the energy range of 4-12 keV. Observations performed during the early calibration and performance verification phase as well as during the on-going all-sky survey that started on 12 Dec. 2019 have demonstrated that the in-flight characteristics of the ART-XC telescope are very close to expectations based on the results of ground calibrations. Upon completion of its 4-year all-sky survey, ART-XC is expected to detect ∼ 5000 sources (∼ 3000 active galactic nuclei, including heavily obscured ones, several hundred clusters of galaxies, ∼ 1000 cataclysmic variables and other Galactic sources), and to provide a high-quality map of the Galactic background emission in the 4-12 keV energy band. ART-XC is also well suited for discovering transient X-ray sources. In this paper, we describe the telescope, results of its ground calibrations, major aspects of the mission, the in-flight performance of ART-XC and first scientific results.

Discovery of the 5 keV cyclotron line followed by three harmonics in SwiftJ1626.6-5156

“…The sky region around Swift J1626.6-5156 was scanned by SRG on Mar 12, 2021. Both the Mikhail Pavlinsky ART-XC telescope (Pavlinsky et al 2021) and the eROSITA telescope (Predehl et al 2021) onboard the SRG observatory detected the source with the high significance (Molkov et al 2021). The source flux in the 2-10 keV energy band resulted from the joint fit of the ART-XC and eROSITA spectra is shown in Fig.…”

SRGA J124404.1-632232/SRGU J124403.8-632231: a new X-ray pulsar discovered in the all-sky survey by SRG

“…As already mentioned, there are two telescopes on board SRG, i.e. eROSITA and ART-XC described in detail in Predehl et al (2021) and Pavlinsky et al (2021), respectively. Due to the comparatively low exposures achieved up to now in the survey, data from both instruments were mostly used to obtain a precise position of the X-ray source, and measure flux variations between the three consequent surveys, whereas NuSTAR data were used for detailed spectral and timing analysis.…”

“…ART-XC data were processed with the analysis software ARTPRODUCTS v0.9 with the calibration files version 20200401. A description of the ART-XC telescope and the analysis software can be found in Pavlinsky et al (2021). Taking into account the faintness of the source and the significantly shorter effective exposure for ART-XC due to its smaller field of view, it was only possible to detect the source and estimate the number of counts above the background.…”

“…In total, eight complete scans of the celestial sphere, each lasting six months are foreseen to be conducted with each of the two instruments on board SRG, i.e. eROSITA (Merloni et al 2012;Predehl et al 2021) operating in the 0.2-10 keV, and the Mikhail Pavlinsky ART-XC (Pavlinsky et al 2021) operating in the 4-30 keV energy range. Both instruments produce standard X-ray event data and produce not only images, but also spectra and light-curves for each point on the sky.…”

SRG/eROSITA discovery of a large circular SNR candidate G116.6-26.1: SN Ia explosion probing the gas of the Milky Way halo?

“…The SRG X-ray observatory (Sunyaev et al 2021) with the two wide-angle grazing-incidence X-ray telescopes, eROSITA (0.3-10 keV, Predehl et al 2021) and Mikhail Pavlinsky ART-XC telescope (4-30 keV, Pavlinsky et al 2021), was launched on July 13, 2019, and started its all-sky X-ray survey on December 13, 2019, upon completion of the commissioning, calibration, and performance verification observations. By mid June 2021, there consecutive scans of the entire sky have been acquired, resulting in the accumulated exposure time from ∼ 700 s at the ecliptic equator to ∼130 ks at the ecliptic poles.…”