Gravitational wave searches for ultralight bosons with LIGO and LISA

Abstract

Ultralight bosons can induce superradiant instabilities in spinning black holes, tapping their rotational energy to trigger the growth of a bosonic condensate. Possible observational imprints of these boson clouds include (i) direct detection of the nearly monochromatic (resolvable or stochastic) gravitational waves emitted by the condensate, and (ii) statistically significant evidence for the formation of "holes" at large spins in the spin versus mass plane (sometimes also referred to as "Regge plane") of astrophysical black holes. In this work, we focus on the prospects of LISA and LIGO detecting or constraining scalars with mass in the range $m_s\in [10^{-19},\,10^{-15}]$ eV and $m_s\in [10^{-14},\,10^{-11}]$ eV, respectively. Using astrophysical models of black-hole populations and black-hole perturbation theory calculations of the gravitational emission, we find that LIGO could observe a stochastic background of gravitational radiation in the range $m_s\in [2\times 10^{-13}, 10^{-12}]$ eV, and up to $\sim 10^4$ resolvable events in a $4$-year search if $m_s\sim 3\times 10^{-13}\,{\rm eV}$. LISA could observe a stochastic background for boson masses in the range $m_s\in [5\times 10^{-19}, 5\times 10^{-16}]$, and up to $\sim 10^3$ resolvable events in a $4$-year search if $m_s\sim 10^{-17}\,{\rm eV}$. LISA could further measure spins for black-hole binaries with component masses in the range $[10^3, 10^7]~M_\odot$, which is not probed by traditional spin-measurement techniques. A statistical analysis of the spin distribution of these binaries could either rule out scalar fields in the mass range $[4 \times 10^{-18}, 10^{-14}]$ eV, or measure $m_s$ with ten percent accuracy if light scalars in the mass range $[10^{-17}, 10^{-13}]$ eV exist

Gravitational collider physics

“…There is an extensive literature on superradiance with scalar [21][22][23][36][37][38][39][40][41][42][43][44][45] and vector fields [35,[46][47][48][49][50][51][52][53][54][55][56]. We will briefly review the key features that will be relevant for the analysis in this paper.…”

Tidal effects and disruption in superradiant clouds: A numerical investigation

“…where we assume the companion to be much lighter than the BH. The GW flux emitted by the cloud-BH system scales as [14,16,34] E cloud ∼ 1 50…”

“…with M S the mass in the scalar cloud [14,16,34]. Therefore, in the context of GW emission and detection, for all practical purposes, disruption will not affect our ability to probe the system: if it was visible via monochromatic emission by the cloud before disruption, it will be seen after disruption as a binary.…”

“…The existence of superradiant clouds would lead to observable signatures, such as peculiar holes in the massspin plane of BHs [13,14], to monochromatic emission of GWs [14,15] and to a significant stochastic background of GWs [16,17]. The presence of such periodic, nonaxisymmetric structures can leave imprints in planetary and stellar orbits, through Lindblad and co-rotation resonances [18,19], or -of interest for GW astronomythrough floating or sinking orbits [20][21][22][23].…”

Constraints on anharmonic corrections of fuzzy dark matter

“…Aside from the standard searches for axions, there is a wealth of dedicated searches and projected experiments on the lookout for ultralight axions. These include studies of the neutral hydrogen distribution in the universe [31,32], laboratory constraints based on nuclear interactions [33], variation of fundamental constants [34,35], astrophysical bounds [36][37][38], gravitational wave searches [39,40] and analysis of CMB spectral distortions [41,42]. A prominent feature of the model is the presence of anharmonic corrections over the mass -2 -…”