KFU and Institute of Space Research observe new properties of galaxies
Over 500 galaxies with active cores have been analysed by KFU’s Department of Astronomy and Space Geodesy and their colleagues from the Russian Academy of Sciences during studies of X-ray data.
The catalog comprises 173,000 starts and is based on data obtained by eROSITA X-ray telescope, part of the Spektr-RG orbital observatory. The results were publicized during a conference at the Institute of Space Research and saw light in Pisma v astronomicheskiy zhurnal (“Letter to the Astronomical Journal”).
The described galaxies have unexpectedly significant proper motions. As co-author, Chair of the Department of Astronomy and Space Geodesy Ilfan Bikmaev explains, proper motion is is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky and is typically measured in milliarcseconds per year. Galaxies and quasars are expected to have extremely small proper motion speeds because of their distance from our galaxy.
“Visual inspection of these unusual space objects (based on optical images available in the public domain in the electronic astronomical databases of the PANSTARRS project) indicated their extended morphology, characteristic of extragalactic sources. For the spectral identification of the first group of these unique sources, an observational program was organized in autumn 2022 at the Russian-Turkish telescope RTT-150 at KFU. The results of the observations were stunning – 18 out of 19 studied sources demonstrated an extragalactic nature and turned out to be active galactic nuclei, located on average at redshifts z = 0.05 – 0.25. This corresponds to distances of 1–3 billion light years from us,” explains Bikmaev. “The presence of a significant proper motion for extragalactic sources can be a manifestation of a change in the object’s photocenter if there are several variable sources inside the scanning window of the GAIA radiation detectors. Back in 1999, American scientists using the Hubble Space Telescope measured the shift of superluminal details in a relativistic jet in the active core of the M87 galaxy for about 5 years, and some details showed a visible shift of up to 6 speeds of light. This is a well-known effect of special relativity, which manifests itself in the case of ultra-relativistic velocities of particles or bodies when they move at speeds extremely close to the speed of light.”
In 2022, the GAIA team confirmed that such quasars and active galactic cores with anomalous proper motions indeed do exist and are not just instrumental errors in GAIA equipment.
“The original spectral observations of such sources on RTT-150, discovered primarily on the basis of X-ray data from the eROSITA, should draw the attention of observers to the problem of the internal variability of galactic nuclei and the presence in them (along with the central source) of variable radiation sources of comparable brightness at appreciable distances exceeding light years. Such phenomena are no exception: there are already more than 500 such objects in the catalog,” opines the interviewee.
Observations of such sources will continue in 2023.