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Contribution
Multi-messaging prelude: precursors of gravitational wave emitters at the milliarcsecond scale
Speakers
- Prof. Leonid GURVITS
- Dr. Sándor FREY
Primary authors
- Prof. Leonid GURVITS (JIVE)
Co-authors
- Prof. Alexander POLNAREV (Queen Mary University of London, London, United Kingdom)
- Dr. Sándor FREY (HUN-REN Research Centre for Astronomy and Earth Sciences)
- Dr. Oleg TITOV (Geoscience Australia, PO Box 378, Canberra 2601, Australia)
Content
Formation of super-massive black holes binaries (SMBHB) is one of the most challenging problems of theoretical astrophysics, as well as observational astronomy in electromagnetic and gravitational wave domains. A process of inevitable dissipation of kinetic energy in SMBHB controls the evolution of these objects (also referred to as inspiralling or recoiling) and leads toward coalescing into a single black hole. This process is accompanied by increasingly intensive emission of gravitational waves (GW) and ends with the final GW burst. While the first direct detection of GW made by the LIGO and Virgo collaboration in 2015 dealt with coalescence of stellar-mass black holes [1], recent results based on multiple Pulsar Timing Arrays (PTA) [2, and references therein] triggered increased interest to the SMBHB population as a likely source of the GW background. However, SMBHB sources remain rather elusive: at present, there are only several dozens of candidates of which just a handful can be treated as certain cases. Besides several directly detected dual active galactic nuclei (AGN) with separations between black holes measured in hundreds kiloparsec, thus belonging to early stages of the SMBHB evolution, closer binary systems in more advanced stages of inspiralling are mostly suspected on the basis of temporal variability or morphological patterns of milliarcsecond-scale structures [3, section 6, and references therein]. Direct detections of the components of SMBHB at the sub-parsec scales, which correspond to the late stages of inspiralling, remain beyond reach for today’s observing techniques at all domains of the electromagnetic spectrum.
Recently we noted several AGNs distinguished by oscillating astrometric positions at the milliarcsecond angular scale and periods of several years. One of plausible explanations of such the behavior is orbital motion of the components of SMBHB [6,4]. We emphasise that VLBI images in our study do not allow us to see’’ directly the components of possible SMBHBs. But we see a
smoking gun’’ of orbital motion in these potential SMBHBs. We will demonstrate several examples of such the oscillating behavior in VLBI astrometry data in quasars 0119+115, 2101+600 and 2234+282. Using the available observational data as starting points we reconstruct physical models of these potential SMBHBs. At the next step we analyse the evolution of these binary systems leading to coalescence and associated with this GW outburst (``a chirp’’ as it is commonly called in the GW detection context).
The work offers an example of VLBI study of a potential GW event precursor. It can be seen as a multi-messenger prediction. It also offers a new vantage point for quantitative explanation of the recent PTA results.
Finally, we demonstrate how the estimates presented in this work offer inputs into design studies of future mm/sub-mm VLBI systems with spaceborne radio telescopes. Such the systems [5, and references therein] will allow us to resolve images of binary SMBHBs at the microarcsecond angular scales, principally unachievable with the Earth-based observational facilities.
References [1] Abbott, B. P., Abbott, R., Abbott, T. D., et al. 2016, Phys. Rev. Lett., 116, 061102 [2] Agazie, G., Anumarlapudi, A., Archibald, A. M., et al. 2023, Astropys. J., 956, L3 [3] Ayzenberg, D., Blackburn, L., Brito, R., et al. 2023, arXiv:2312.02130 [4] Gurvits, L. I., Frey, S., Krezinger, M., et al. 2023, in The Multimessenger Chakra of Blazar Jets, ed. I. Liodakis, et al., Vol. 375, 86-90 [5] Gurvits, L.I., Paragi Z., Amils, R., et al., 2022, Acta Astronautica, 196, 314-333 [6] Titov, O., Frey, S., Melnikov, A., et al. 2023, Astronomical J., 165, id 69