The missing link in gravitational-wave astronomy

Abstract

Since 2015 the gravitational-wave observations of LIGO and Virgo have transformed our understanding of compact-object binaries. In the years to come, ground-based gravitational-wave observatories such as LIGO, Virgo, and their successors will increase in sensitivity, discovering thousands of stellar-mass binaries. In the 2030s, the space-based LISA will provide gravitational-wave observations of massive black holes binaries. Between the $\sim 10$ ∼ 10 –103 Hz band of ground-based observatories and the $\sim 10^{-4}$ ∼ 1 0 − 4 –10− 1 Hz band of LISA lies the uncharted decihertz gravitational-wave band. We propose a Decihertz Observatory to study this frequency range, and to complement observations made by other detectors. Decihertz observatories are well suited to observation of intermediate-mass ($\sim 10^{2}$ ∼ 1 0 2 –104M⊙) black holes; they will be able to detect stellar-mass binaries days to years before they merge, providing early warning of nearby binary neutron star mergers and measurements of the eccentricity of binary black holes, and they will enable new tests of general relativity and the Standard Model of particle physics. Here we summarise how a Decihertz Observatory could provide unique insights into how black holes form and evolve across cosmic time, improve prospects for both multimessenger astronomy and multiband gravitational-wave astronomy, and enable new probes of gravity, particle physics and cosmology.

Cold Atoms in Space: Community Workshop Summary and Proposed Road-Map

“…The shaded regions are excluded by current experiments including MICROSCOPE [189] and atomic clocks [85]. 11 We also show the prospective sensitivities of rubidium-based terrestrial interferometers (MIGA [182] and ELGAR [180]) and strontium-based terrestrial and space-borne atom interferometers (AION [181] and AEDGE [5], respectively). MIGA, ELGAR and the 100 m and km versions of AION offer significantly greater sensitivity than current experiments (torsion balances, atomic clocks and MICROSCOPE [189]) to couplings of scalar ULDM with masses 10 −12 eV to both photons and electrons.…”

“…The deployment of cold atom technologies in space offers unique research opportunities in the fields of fundamental physics, cosmology and astrophysics, as represented in several White Papers submitted to the ESA Voyage 2050 call for mission concepts [4,[6][7][8][9][10][11]. We focus in the following on two of these mission concepts.…”

“…It built upon one organised two years ago [3], which reviewed the landscape of present and prospective cold atom experiments in space. Subsequently, several White Papers were submitted [4][5][6][7][8][9][10][11][12] in response to the Voyage 2050 call, which outlined possible ultimate goals and reviewed experiments and technical developments underway that could help pave a way towards these goals.…”

Extended reduced-order surrogate models for scalar-tensor gravity in the strong field and applications to binary pulsars and gravitational waves

“…So far, however, limited by the sensitivity of the LIGO/Virgo detectors below tens of hertz, the bound on dipolar radiation from GW170817 is still looser than that from the timing of binary pulsars [28,36], since dipolar radiation corresponds to a −1 PN correction and plays a relatively important role when v/c 1. Future ground-based and space-based GW detectors with a better low-frequency sensitivity, such as Cosmic Explorer (CE) [37], Einstein Telescope (ET) [38], DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) [39] and Decihertz Observatory (DO) [40,41] will place tighter constraints on gravity theories by either extending the sensitivity bands to be below 10 Hz or increasing the sensitivity further (see e.g. Ref.…”

Probing dipole radiation from binary neutron stars with ground-based laser-interferometer and atom-interferometer gravitational-wave observatories

“…Given the above detectors, there remains a frequency gap spanning 10 −1 -10 Hz. To fulfill it, a bulk of decihertz GW detectors are proposed, broadly speaking including (i) space-borne laser interferometer detectors like the Decihertz Observatory (DO) [38,39] and the DECihertz laser Interferometer GW Observatory (DECIGO) [40,41], and (ii) ground-based atom interferometer detectors. Recently, Liu et al [42] investigated the projected constraints on dipole radiation from AdvLIGO, LISA and the spaceborne decihertz detectors.…”