An interacting dark sector and the implications of the first gravitational-wave standard siren detection on current constraints

Abstract

After the first nearly simultaneous joint observations of gravitational-waves and electromagnetic emission produced by the coalescence of a binary neutron star system, another probe of the cosmic expansion which is independent from the cosmic distance ladder, became available. We perform a global analysis in order to constrain an interacting dark energy model, characterised by a conformal interaction between dark matter and dark energy, by combining current data from: Planck observations of the cosmic microwave background radiation anisotropies, and a compilation of Hubble parameter measurements estimated from the cosmic chronometers approach as well as from baryon acoustic oscillations measurements. Moreover, we consider two measurements of the expansion rate of the Universe today, one from the observations of the Cepheid variables, and another from the merger of the binary neutron star system GW170817. We find that in this interacting dark energy model, the influence of the local measurement of the Hubble constant mostly affects the inferred constraints on the coupling strength parameter between dark energy and dark matter. However, the GW170817 Hubble constant measurement is found to be more conservative than the Cepheid variables measurement, and in a better agreement with the current high redshift cosmological data sets. Thus, forthcoming gravitational-wave standard siren measurements of the Hubble constant would be paramount for our understanding of the dark cosmic sector.

Constraining primordial non-Gaussianity using two galaxy surveys and CMB lensing

“…For this reason, in the absence of any salient features in the primordial power spectrum, which might open a new observational window on high energy physics happening in the early Universe (Chen et al 2015), SFSR constraints in the next decade will likely be limited to improvements to the constraints on the scalar spectral index and the tensor-to-scalar ratio. The prospects of detecting the running of the scalar spectral index, that Contact e-mail: mario.ballardini@gmail.com † Contact e-mail: willmatt4th@gmail.com ‡ Contact e-mail: roy.maartens@gmail.com arises in SFSR models at second-order in slow-roll parameters (dn s /d ln k ∝ (n s − 1) 2 ), may be nearly impossible even with next-generation cosmological surveys (Ballardini et al 2016;Muñoz et al 2017;Li et al 2018;Mifsud & van de Bruck 2019).…”

Forecast for cosmological parameter estimation with gravitational-wave standard sirens from the LISA-Taiji network

“…Therefore, the current development of cosmology can be divided into two main aspects: (i) further extending the standard ΛCDM model [8][9][10]; and (ii) developing more low-redshift observation projects aimed at precisely measuring the late universe. For the second aspect, the gravitational-wave (GW) standard siren [11] is one of the most promising options and has been widely discussed [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

Constraints on interacting dark energy models through cosmic chronometers and Gaussian process

“…Complementary studies have investigated how the growth of instabilities in interacting dark models affects the formation of astrophysical structures [41][42][43][44][45][46][47][48], such as primordial black holes [49][50][51], and galactic halos [52][53][54][55][56][57][58][59][60][61][62] due to the fact that the density of dark matter does not dilute any longer with the cube of the scale factor of the universe. Gravitational waves has been used for constraining dark interactions as well [63][64][65][66]. Moreover, a coupling between the dark energy field and dark matter, with the latter pictured as neutrinos, affects the neutrinos' masses estimates [67][68][69].…”