The status of DECIGO

Binary white dwarfs and decihertz gravitational wave observations: From the Hubble constant to supernova astrophysics

“…DECIGO is planned to be composed of four clusters of three spacecrafts each. The latter are separated by 1000 km, forming a triangular configuration that moves on a Helio-centric orbit [57]. In this configuration we identify two reference systems: one aligned with the detector, and one fixed with the barycenter: we attach to these two systems the coordinates (x, y, z) and (x,ȳ,z), respectively.…”

“…We show how, in a multi-messenger scenario, BWDs are a complementary and independent tool to measure H 0 and are able to provide new insights on the fundamental physics of the SN explosion. Gravitational signals are assumed to be observed by the Japanese decihertz interferometers DECIGO and B-DECIGO [22,57,58]. We focus on the constraints that these detectors will be able to put on the luminosity distance and on the Hubble constant, by exploiting the redshift inferred by the spectrum of SN or its host galaxy.…”

Thermal history of the early Universe and primordial gravitational waves from induced scalar perturbations

“…The results for the first order and second order PGW are shown in fig. 5 in addition to the different experimental constraints [28][29][30][31][32][33][34][35][36][37] and the BBN bound [12] as outlined in the legend of the plot (the suffix number for the SKA experiment shows the constraints based on the number of years in operation). In case of scale invariance the relic of the first order PGW can have any value from ∼ 10 −16 down to the lower limit by the induced PGW of ∼ 10 −23 depending on the value of r. If r 10 −9 then the scalar induced contribution on the PGW will be dominating.…”

“…The spectrum of the PGW from the scale invariant first order tensor perturbations (blue dashed line) assuming the maximum value of tensor-to-scalar ratio r = 0.07 from the upper limit of Planck data [26] and the induced PGW using the observed value of scalar perturbation amplitude AR = 2.1 × 10 −9 assuming the scale invariance (green solid line), a scale dependence with ns = 0.96 (green dotted line), and ns = 1.5 (green dot-dashed line) as shown in the plot. Also, some current and future experimental constraints [28][29][30][31][32][33][34][35][36][37] and the BBN bound are shown (see the text for details). presence of non-Gaussianity in the curvature power spectrum one gets [18][19][20]…”

“…However, future detectors will be able to probe much smaller signatures from possible phase transitions and the PGW in the early Universe cosmology. Some of these planned GW missions are the Laser Interferometer Space Antenna (LISA) [28], the Einstein Telescope (ET) [29], the Deci-hertz Interferometer Gravitational wave Observatory (DECIGO and B-DECIGO) [30,31], the Big Bang Observatory (BBO) [32], the Square Kilometer Array (SKA) telescope [33], the North American Nanohertz Observatory for Gravitational Waves (NanoGrav) [34], and the European Pulsar Timing Array (EPTA) [35]. Moreover, LIGO can be sensitive to the predicted GW for the early Universe depending on the model [36,37].…”