Probing ultralight bosons with extreme-mass-ratio-inspirals


  • Call:

    PT-CERN Call 2022/2

  • Academic Year:


  • Domain:

    Astroparticle Physics

  • Supervisor:

    Richard Brito

  • Co-Supervisor:

  • Institution:

    Instituto Superior Técnico (Universidade de Lisboa)

  • Host Institution:

    CENTRA - Center for astrophysics and gravitation

  • Abstract:

    Gravitational-wave (GW) observations have an enormous potential to help solving long-standing problems in fundamental physics. Recently, it has become clear that these observations open new opportunities to help us to characterize and identify dark matter [1]. Many proposals have been put forward about how GWs can gives us information about dark matter and its nature [1]. This project will be devoted to study one of such proposals. The main goal will be to study how the existence of ultralight bosons (particles with masses below the eV scale proposed as dark matter candidates (see e.g. [2]) could affect the GW emission from binary black holes (BHs). These particles are specially interesting in this respect because they can have Compton wavelengths as large as astrophysical BHs, leading to a plethora of interesting effects (see e.g. [2,3]) such as the formation of very long-lived structures, or “boson clouds” around spinning BHs that can be observed through several channels [3], including through GW observations. Recent developments have shown that, if existent, ultralight bosons could significantly modify the dynamics of binary BH systems leaving clear imprints in the GWs emitted the binary (see e.g. [4,5,6]). Within this context, in this project we will consider the so-called extreme-mass-ratio inspirals (EMRIs), binary systems in which a stellar-mass compact object, orbits a supermassive BH with millions of solar masses. These sources are expected to be detected by the future space-based GW detector LISA with extreme precision [7]. Most studies considering EMRIs evolving within boson clouds relied on non-relativistic approximations [4,5,6] and simplistic assumptions about the orbital dynamics, insufficient for an accurate description of these systems. This project will go beyond those simplifications by studying EMRIs evolving within bosons clouds using a fully relativistic setting: a necessary stepping-stone in order to be prepared for the future LISA mission.