Asymmetric binaries meet fundamental physics: an inspiral journey from fluxes to waveforms to data analysis

Sara Glorio (Gran Sasso Science Institute)

Time:

2PM Wednesday, 18 March 2026

Location:

Science East, E0.32

The LISA satellite, recently adopted by ESA, is ready to open a new gravitational wave window, targeting sources that are inaccessible to ground-based detectors like LIGO and Virgo.

Extreme mass-ratio inspirals (EMRIs), composed by a massive black hole and a stellar mass secondary, are among the most peculiar of such new family of binaries. The inspiral phase of these systems falls within the mHz regime of the LISA band. Depending on their mass ratios, EMRIs will be continuously observed over long periods, ranging from months to years. Such long evolution is key to provide a measurement of the source parameters with exceptional accuracy, and to allow precise tests of vacuum General Relativity scenarios.

In this talk, I will discuss two distinct scientific cases: one beyond-vacuum scenario and one beyond-General Relativity scenario.

First, I will show how, from a theoretical standpoint, we can model the dynamics of EMRIs embedded in dark matter halos within a fully relativistic framework. Building on this, I will demonstrate how different dark matter profiles, such as Hernquist, Navarro-Frenk-White, and Einasto, affect the inspiral dynamics, and whether LISA could detect their imprints and distinguish among these models.

In the second part, I will explore a beyond-General Relativity scenario in which the secondary compact object carries a scalar charge. I will describe how to compute the scalar energy fluxes emitted by such EMRIs when the secondary follows generic (eccentric and inclined) orbits. This computation is performed using a new C++ code, STORM (Scalar-Tensor Orbital Radiation from EMRIs), which calculates both scalar and gravitational energy fluxes.

Finally, I will present the first results obtained with this code and discuss the detectability of the scalar charge in asymmetric binaries, highlighting how the resulting constraints depend on the mass ratio.