Perspectives for multi-messenger astronomy with the next generation of gravitational-wave detectors and high-energy satellites

Abstract

The Einstein Telescope (ET) is going to bring a revolution for the future of multi-messenger astrophysics. In order to detect the counterparts of binary neutron star (BNS) mergers at high redshift, the high-energy observations will play a crucial role. Here, we explore the perspectives of ET, as single observatory and in a network of gravitational-wave (GW) detectors, operating in synergy with future γ-ray and X-ray satellites. We predict the high-energy emission of BNS mergers and its detectability in a theoretical framework which is able to reproduce the properties of the current sample of observed short GRBs (SGRB). We estimate the joint GW and high-energy detection rate for both the prompt and afterglow emissions, testing several combinations of instruments and observational strategies. We find that the vast majority of SGRBs detected in γ-rays will have a detectable GW counterpart; the joint detection efficiency approaches 100% considering a network of third generation GW observatories. The probability of identifying the electromagnetic counterpart of BNS mergers is significantly enhanced if the sky localisation provided by GW instruments is observed by wide field X-ray monitors. We emphasize that the role of the future X-ray observatories will be very crucial for the detection of the fainter emission outside the jet core, which will allow us to probe the yet unexplored population of low-luminosity SGRBs in the nearby Universe, as well as to unveil the nature of the jet structure and the connections with the progenitor properties.

Prospects of testing late-time cosmology with weak lensing of gravitational waves and galaxy surveys

“…(4.7) as z 0 = 1.5. This corresponds to a phenomenological parametrization for the normalized distribution of observed sources that we make compatible with both the forecasts of [83] for LISA luminous MBHB observations and of [79] for the BNS observed by a network of ET in combination with two CE detectors. The reason for choosing this parametrization is the attempt of remaining as detector a-specific as possible, while still modeling our sources distribution to mimick forecasted future observations.…”

“…This same degeneracy can also be reduced through the measurement of higher modes of the GW signal [64,65] or exploiting external information such as, in case the binary merger is accompanied by the emission of a relativistic jet, the angle of the jet with respect to the line of sight [66][67][68][69] As the GW strain can be parameterized in terms of the redshifted masses of the binary objects, GW sources cannot probe independently the redshift of the source unless there is a known mass-scale or physical scale which can be used to break the degeneracy between mass and redshift [70][71][72][73][74]. For some GW sources such as BNS [75][76][77][78][79], NS-BH [80,81], stellar and intermediate mass BBH [82] and massive BBHs [83][84][85] embedded in accretion disks, a detectable electromagnetic counterpart can potentially be observed and used to measure its redshift directly with a spectroscopic (or photometric) follow-up of the host galaxy. These sources are typically dubbed 'bright' sirens.…”

GWFish: A simulation software to evaluate parameter-estimation capabilities of gravitational-wave detector networks

“…Other more detailed studies carried out with gwfish have been published in separate papers. These include the evaluation of the perspectives of multi-messenger observations for ET (as single observatory and in network of GW detectors) operating in synergy with γ and X-ray satellites using astrophysically motivated populations of BNS mergers [25], and very high-energy observatories (Banerjee et al 2022 in preparation). gwfish was also used for the simulation of an astrophysical background in the ET null-stream study [26].…”

X- and Gamma-ray astrophysics in the era of Multi-messenger astronomy

“…By the end of the twenties, the completed GW detector network will have improved sky localisation capabilities, with average uncertainty regions of the order of few tens of square degrees for CBCs [4]. During the thirties, the GW source localisation will still rely mostly on the triangulation method and therefore will depend on the presence of a network of 3G interferometers [66,24,85]. In the local Universe, however, the high signal to noise ratio with which CBC events will be detected will make it possible to have some sky localization capabilities even if they work separately.…”

“…This will allow us to exploit the effects of Earth rotation on the signal in the GW source sky localization computation. ET alone will be able to detect a few hundreds of NS-NS mergers per year with sky-localization less than ∼100 square degrees [85] up to redshift z ∼ 0.8 while a network including ET and CE will detect thousands of events with sky-localization less than 10 square degrees. At larger distances (z > 0.8), the sky localization accuracy decreases to several tens to hundreds of square degrees for the large majority of the events [85].…”