Reconstructing the dark sector interaction with LISA

TL;DR

This paper assesses the potential of the LISA space-based GW detector to reconstruct a possible interaction between vacuum dark energy and dark matter using high-redshift standard sirens from massive black hole binary mergers. It employs a model-independent Gaussian process reconstruction of the distance–redshift relation, incorporating three MBHB formation scenarios and two LISA mission durations, and then uses the reconstructed distances to infer the dark sector coupling $q(z)=Q/H_0^3$. The authors explore two data combinations: LISA MBHB standard sirens alone and LISA MBHB standard sirens plus DES supernovae, finding that LISA alone can constrain the interaction well in $z\sim1$–$3$ (5 years) or up to $z\sim5$ (10 years), with DES extending constraints to $z\sim0$–$3$ (5 years) or $z\sim0$–$5$ (10 years). The results demonstrate that GW standard sirens provide a powerful, complementary probe of possible deviations from $\Lambda$CDM at high redshift and highlight the potential gains from combining GW and EM datasets.

Abstract

We perform a forecast analysis of the ability of the LISA space-based interferometer to reconstruct the dark sector interaction using gravitational wave (GW) standard sirens at high redshift. We employ Gaussian process methods to reconstruct the distance-redshift relation in a model independent way. We adopt simulated catalogues of standard sirens given by merging massive black hole binaries (MBHBs) visible by LISA, with an electromagnetic (EM) counterpart detectable by future telescopes. The catalogues are constructed considering three different astrophysical scenarios for the evolution of MBHB mergers based on the semi-analytic model of E. Barausse (2012). We first use these standard siren datasets to assess the potential of LISA in reconstructing a possible interaction between vacuum dark energy and dark matter. Then we combine the LISA cosmological data with supernovae data simulated for the Dark Energy Survey (DES). We consider two scenarios distinguished by the time duration of the LISA mission: 5 and 10 years. Using only LISA standard siren data, the dark sector interaction can be well reconstructed from redshift $z\sim1$ to $z\sim3$ (5 yr) and $z\sim1$ up to $z\sim5$ (10 yr), though the reconstruction is inefficient at lower redshift. When combined with the DES datasets, the interaction is well reconstructed in the whole redshift region from $z\sim0$ to $z\sim3$ (5 yr) and $z\sim0$ to $z\sim5$ (10 yr). MBHB standard sirens can thus be used to constrain the dark sector interaction at redshift ranges not reachable by usual supernovae datasets which probe only the $z\lesssim 1.5$ range. GW standard sirens will not only constitute a complementary and alternative way, with respect to familiar EM observations, to probe the cosmic expansion, but will also provide new tests to constrain possible deviations from the standard $Λ$CDM dynamics, especially at high redshift.

Figures (13)

• Figure 1: Reconstruction of the distance $D(z)$ using LISA alone for a 5 years mission. From left to right each column reports the results for popIII, Q3d, Q3nod. The shaded blue regions are the 68% and 95% C.L. of the reconstructed function.
• Figure 2: Reconstructions of the interaction using LISA alone for a 5 years mission. From left to right each column reports the results for popIII, Q3d, Q3nod.
• Figure 3: Reconstruction of the distance $D(z)$ using LISA alone for a 10 years mission. From left to right each column reports the results for popIII, Q3d, Q3nod. The shaded blue regions are the 68% and 95% C.L. of the reconstruction.
• Figure 4: Reconstructions of the interaction using LISA alone for a 10 years mission. From left to right each column reports the results for popIII, Q3d, Q3nod.
• Figure 5: Reconstruction of the distance $D(z)$ using DES$+$LISA for a 5 years mission. From left to right each column reports the results for popIII, Q3d, Q3nod. The shaded blue regions are the 68% and 95% C.L. of the reconstruction.