# X-ray Emission of ICRF Sources

## TL;DR

This study examines X-ray emissions of ICRF sources, highlighting variability in certain active galactic nuclei like blazars, and discusses their implications for the stability and proper motion within the celestial reference frame.

## Contribution

It provides the first analysis of X-ray emission characteristics of ICRF sources, identifying active processes and potential proper motions in selected extragalactic radio sources.

## Key findings

- 54 X-ray sources identified among ICRF references
- Rapid variability observed in blazars 2E 2673 and 2E 1802
- Most X-ray sources are stable, with some active AGNs showing significant variability.

## Abstract

Considering increasing requirements to the coordinates measurement precision by the end of XX century International Astronomical Union commenced implementation of the new astrometric system ICRF (International Celestial Reference Frame). This quasi-inertial reference frame system centered in the barycenter of the Solar System and has axes defined by the positions of distant extragalactic sources - frames. Unlike equatorial system ICRF has no shortcomings of the coordinates identification due to the Earth axis precession, stellar proper motions and other factors. Extragalactic frames of the ICRF system are mostly quasars, radio galaxies, blazars and Seyfert galaxies i.e. different types of the active galaxy nuclei (AGN). Active galaxy nuclei are characterized by processes with significant. Such processes quite often are followed by X-ray emission generation. The purpose of this work is to consider X-ray emission of ICRF sources and features of their possible proper motions. Among 295 selected reference frames of the system we identified 54 X-ray sources which were observed by space observatory XMM Newton and noticed rapid variability of the blazars 2E 2673 (W Com) and 2E 1802 which enables to conclude that they have some very active processes in the sources centers. With regards to the future more detailed analysis we beleive that evidences of the objects proper motion could be found in their spectra. Based on the constructed luminosity and spectral graphs we could conclude that apart from above mentioned AGNs rest 52 objects do not show veriability and special attention should be paid to blazars within ICRF system development and use. Major part of the X-ray sources between the reference frames are stable.