LISA constraints on an intermediate-mass black hole in the Galactic Centre

Vladimir Strokov*, Giacomo Fragione*, Emanuele Berti*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Galactic nuclei are potential hosts for intermediate-mass black holes (IMBHs), whose gravitational field can affect the motion of stars and compact objects. The absence of observable perturbations in our own Galactic Centre has resulted in a few constraints on the mass and orbit of a putative IMBH. Here, we show that the Laser Interferometer Space Antenna (LISA) can further constrain these parameters if the IMBH forms a binary with a compact remnant (a white dwarf, a neutron star, or a stellar-mass black hole), as the gravitational-wave signal from the binary will exhibit Doppler-shift variations as it orbits around Sgr A. We argue that this method is the most effective for IMBHs with masses 103 M ≲ MIMBH ≲ 105 M and distances of 0.1–2 mpc with respect to the supermassive black hole, a region of the parameter space partially unconstrained by other methods. We show that in this region the Doppler shift is most likely measurable whenever the binary is detected in the LISA band, and it can help constrain the mass and orbit of a putative IMBH in the centre of our Galaxy. We also discuss possible ways for an IMBH to form a binary in the Galactic Centre, showing that gravitational-wave captures of stellar-mass black holes and neutron stars are the most efficient channel.

Original languageEnglish (US)
Pages (from-to)2033-2041
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Sep 1 2023


  • Galaxy: centre
  • black hole physics
  • gravitational waves
  • techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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