Next Generation Of Gravitational Wave Detectors Research Articles

Cosmography with next-generation gravitational wave detectors

Advancements in cosmology through next-generation (XG) ground-based gravitational wave (GW) observatories will bring in a paradigm shift. We explore the pivotal role that GW standard sirens will play in inferring cosmological parameters with XG observatories, not only achieving exquisite precision but also opening up unprecedented redshifts. We examine the merits and the systematic biases involved in GW standard sirens utilizing binary black holes, binary neutron stars, and neutron star-black hole mergers. Further, we estimate the precision of bright sirens, golden dark sirens, and spectral sirens for these binary coalescences and compare the abilities of various XG observatories (A ♯ , cosmic explorer, Einstein telescope, and their possible networks). When combining different sirens, we find sub-percent precision over more than 10 billion years of cosmic evolution for the Hubble expansion rate H(z). This work presents a broad view of opportunities to precisely measure the cosmic expansion rate, decipher the elusive dark energy and dark matter, and potentially discover new physics in the uncharted Universe with XG GW detectors.

Systematic bias from waveform modeling for binary black hole populations in next-generation gravitational wave detectors

Systematic bias from waveform modeling for binary black hole populations in next-generation gravitational wave detectors

Prospects for direct detection of black hole formation in neutron star mergers with next-generation gravitational-wave detectors

Prospects for direct detection of black hole formation in neutron star mergers with next-generation gravitational-wave detectors

Combining chirp mass, luminosity distance, and sky localization from gravitational wave events to detect the cosmic dipole

ABSTRACT A key test of the isotropy of the Universe on large scales consists in comparing the dipole in the cosmic microwave background (CMB) temperature with the dipole in the distribution of sources at low redshift. Current analyses find a dipole in the number counts of quasars and radio sources that is 2–5 times larger than expected from the CMB, leading to a tension reaching 5σ. In this paper, we derive a consistent framework to measure the dipole independently from gravitational wave (GW) detections. We exploit the fact that the observer velocity does not only change the distribution of events in the sky, but also the luminosity distance and redshifted chirp mass, which can be extracted from the GW waveform. We show that the estimator with higher signal-to-noise ratio is the dipole in the chirp mass measured from a population of binary neutron stars. Combining all estimators (accounting for their covariance) improves the detectability of the dipole by 30–50 per cent compared to number counting of binary black holes alone. We find that a few 106 events are necessary to detect a dipole consistent with the CMB one, whereas if the dipole is as large as predicted by radio sources, it will already be detectable with 105 events, which would correspond to a single year of observation with next-generation GW detectors. GW sources provide therefore a robust and independent way of testing the isotropy of the Universe.

GRB 211211A-like Events and How Gravitational Waves May Tell Their Origins

GRB 211211A is a rare burst with a genuinely long duration, yet its prominent kilonova association provides compelling evidence that this peculiar burst was the result of a compact binary merger. However, the exact nature of the merging objects, whether they were neutron star pairs, neutron star–black hole systems, or neutron star–white dwarf systems, remains unsettled. This Letter delves into the rarity of this event and the possibility of using current and next-generation gravitational wave detectors to distinguish between the various types of binary systems. Our research reveals an event rate density of for GRB 211211A-like gamma-ray bursts (GRBs), which, assuming GRB 211211A is the only example of such a burst, is significantly smaller than that of typical long- and short-GRB populations. We further calculated that if the origin of GRB 211211A is a result of a neutron star–black hole merger, it would be detectable with a significant signal-to-noise ratio (S/N), given the LIGO-Virgo-KAGRA designed sensitivity. On the other hand, a neutron star–white dwarf binary would also produce a considerable S/N during the inspiral phase at decihertz and is detectable by next-generation spaceborne detectors DECIGO and the Big Bang Observer. However, to detect this type of system with millihertz spaceborne detectors like LISA, Taiji, and TianQin, the event must be very close, approximately 3 Mpc in distance or smaller.

Conceptual design of a sorption-based cryochain for the ETpathfinder

Next-generation gravitational wave detectors, including the Einstein Telescope [1][2], aim to achieve amplitude-spectral-density strain sensitivities on the order 10−24m/Hz[3]. In the low-frequency band such sensitivities can only be obtained when thermal noise, mainly stemming from the mirror coating, is reduced by employing cryogenic cooling techniques for the mirrors. The optical surface of the mirror should not vibrate with strain noise amplitude spectral densities above 10−20m/Hz for the cryogenic mirrors in the Einstein Telescope [3]. The ETpathfinder research facility [4][5], aims to facilitate the development and testing of critical new technologies required for the design and operation of future gravitational wave detectors. A key enabling technology for the design and operation of such advanced interferometers is the cryogenic system that cools the main optics to a temperature of approximately 10 K. Given the stringent requirements on vibrational noise for these optics, the cryogenic cooling under continuous operation should be essentially vibration free. Joule-Thomson cryocoolers using sorption compressors are known to generate an absolute minimum of vibrational noise during operation. We propose a modular cryochain design comprised of a system of sorption compressors and Joule-Thomson cold stages fitting the ETpathfinder project requirements. In this paper, we present the conceptual design of the cooler chain that is based on a parallel cascade arrangement of a 40 K neon stage, a 15 K hydrogen stage and a 8 K helium stage. The operating parameters of the sorption-based cooler chain are selected via a hybrid modeling workflow, aiming to optimize performance and other design considerations within an envelope of acceptable design parameters.

A Data Science Platform to Enable Time-domain Astronomy

SkyPortal is an open-source software package designed to discover interesting transients efficiently, manage follow-up, perform characterization, and visualize the results. By enabling fast access to archival and catalog data, crossmatching heterogeneous data streams, and the triggering and monitoring of on-demand observations for further characterization, a SkyPortal-based platform has been operating at scale for >2 yr for the Zwicky Transient Facility Phase II community, with hundreds of users, containing tens of millions of time-domain sources, interacting with dozens of telescopes, and enabling community reporting. While SkyPortal emphasizes rich user experiences across common front-end workflows, recognizing that scientific inquiry is increasingly performed programmatically, SkyPortal also surfaces an extensive and well-documented application programming interface system. From back-end and front-end software to data science analysis tools and visualization frameworks, the SkyPortal design emphasizes the reuse and leveraging of best-in-class approaches, with a strong extensibility ethos. For instance, SkyPortal now leverages ChatGPT large language models to generate and surface source-level human-readable summaries automatically. With the imminent restart of the next generation of gravitational-wave detectors, SkyPortal now also includes dedicated multimessenger features addressing the requirements of rapid multimessenger follow-up: multitelescope management, team/group organizing interfaces, and crossmatching of multimessenger data streams with time-domain optical surveys, with interfaces sufficiently intuitive for newcomers to the field. This paper focuses on the detailed implementations, capabilities, and early science results that establish SkyPortal as a community software package ready to take on the data science challenges and opportunities presented by this next chapter in the multimessenger era.

Continuous Gravitational Waves from Galactic Neutron Stars: Demography, Detectability, and Prospects

Abstract We study the prospects for the detection of continuous gravitational signals from normal Galactic neutron stars, i.e., nonrecycled stars. We use a synthetic population generated by evolving stellar remnants in time, according to several models. We consider the most recent constraints set by all-sky searches for continuous gravitational waves and use them for our detectability criteria. We discuss the detection prospects for the current and the next generation of gravitational-wave detectors. We find that neutron stars whose ellipticity is solely caused by magnetic deformations cannot produce any detectable signal, not even by third-generation detectors. The currently detectable sources all have B ≲ 1012 G and deformations that are not solely due to the magnetic field. For these, we find in fact that the larger the magnetic field, the higher the ellipticity required for the signal to be detectable, and this ellipticity is well above the value induced by the magnetic field. Third-generation detectors such as the Einstein Telescope and Cosmic Explorer will be able to detect up to ≈250 more sources than current detectors. We briefly treat the case of recycled neutron stars with a simplified model. We find that continuous gravitational waves from these objects will likely remain elusive to detection by current detectors, but should be detectable with the next generation of detectors.

Intracavity signal amplification system for next-generation gravitational-wave detectors

Intracavity signal amplification system for next-generation gravitational-wave detectors

Inferring interference: Identifying a perturbing tertiary with eccentric gravitational wave burst timing

[Abridged] Binary black holes may form and merge dynamically. These binaries are likely to become bound with high eccentricities, resulting in a burst of gravitational radiation at their point of closest approach. When such a binary is perturbed by a third body, the evolution of the orbit is affected, and gravitational-wave burst times are altered. The bursts times therefore encode information about the tertiary. In order to extract this information, we require a prescription for the relationship between the tertiary properties and the gravitational-wave burst times. In this paper, we demonstrate a toy model for the burst times of a secular three-body system. We show how Bayesian inference can be employed to deduce the tertiary properties when the bursts are detected by next-generation ground-based gravitational-wave detectors. We study the bursts from an eccentric binary with a total mass of $60$~M$_\odot$ orbiting an $6 \times 10^{8}$~M$_\odot$ supermassive black hole. When we assume no knowledge of the eccentric binary, we are unable to tightly constrain the existence or properties of the tertiary, and we recover biased posterior probability distributions for the parameters of the eccentric binary. However, when the properties of the binary are already well-known -- as is likely if the late inspiral and merger are also detected -- we are able to more accurately infer the mass of the perturber, $m_3$, and its distance from the binary, $R$. When we assume measurement precision on the binary parameters consistent with expectations for next-generation gravitational-wave detectors, we can be greater than $90\%$ confident that the binary is perturbed. [...]

Degeneracy in the Inference of Phase Transitions in the Neutron Star Equation of State from Gravitational Wave Data.

Gravitational wave (GW) detections of binary neutron star inspirals will be crucial for constraining the dense matter equation of state (EOS). We demonstrate a new degeneracy in the mapping from tidal deformability data to the EOS, which occurs for models with strong phase transitions. We find that there exists a new family of EOS with phase transitions that set in at different densities and that predict neutron star radii that differ by up to ∼500 m but that produce nearly identical tidal deformabilities for all neutron star masses. Next-generation GW detectors and advances in nuclear theory may be needed to resolve this degeneracy.

Seismic noise characterisation at a potential gravitational wave detector site in Australia

A critical consideration in the design of next-generation gravitational wave detectors is the understanding of the seismic environment that can introduce coherent and incoherent noise of seismic origin at different frequencies. We present detailed low-frequency ambient seismic noise characterisation (0.1–10 Hz) at the Gingin site in Western Australia. Unlike the microseism band (0.06–1 Hz) for which the power shows strong correlations with nearby buoy measurements in the Indian Ocean, the seismic spectrum above 1 Hz is a complex superposition of wind induced seismic noise and anthropogenic seismic noise which can be characterised using beamforming to distinguish between the effects of coherent and incoherent wind induced seismic noise combined with temporal variations in the spatio-spectral properties of seismic noise. This also helps characterise the anthropogenic seismic noise. We show that wind induced seismic noise can either increase or decrease the coherency of background seismic noise for wind speeds above 6 m s−1 due to the interaction of wind with various surface objects. In comparison to the seismic noise at the Virgo site, the secondary microseism (0.2 Hz) noise level is higher in Gingin, but the seismic noise level between 1 and 10 Hz is lower due to the sparse population and absence of nearby road traffic.

Primordial black holes and scalar-induced gravitational waves from the perturbations on the inflaton potential in peak theory

A perturbation on the background inflaton potential can lead inflation into the ultraslow-roll stage and can thus remarkably enhance the power spectrum ${\cal P}_{\cal R}(k)$ of the primordial curvature perturbation on small scales. Such an enhanced ${\cal P}_{\cal R}(k)$ will result in primordial black holes (PBHs), contributing a significant fraction of dark matter, and will simultaneously generate sizable scalar-induced gravitational waves (SIGWs) as a secondorder effect. In this work, we calculate the PBH abundances $f_{\rm PBH}(M)$ and SIGW spectra $\Omega_{\rm GW}(f)$ in peak theory. We obtain the PBHs with desirable abundances in one or two typical mass windows at $10^{-17}\, M_\odot$, $10^{-13}\, M_\odot$, and $30\, M_\odot$, respectively. At the same time, the relevant SIGWs are expected to be observed by the next-generation gravitational wave detectors, without spoiling the current constraint. Especially, the SIGW associated with the PBH of $30\, M_\odot$ can also interpret the potential isotropic stochastic gravitational wave background from the NANOGrav 12.5-year dataset.

A Study of Primordial Very Massive Star Evolution

We present new evolutionary models of primordial very massive stars with initial masses ranging from 100 to 1000 M ⊙ that extend from the main sequence to the onset of dynamical instability caused by the creation of electron–positron pairs during core C, Ne, or O burning, depending on the star’s mass and metallicity. Mass loss accounts for radiation-driven winds, as well as pulsation-driven mass loss on the main sequence and during the red supergiant phase. After examining the evolutionary properties, we focus on the final outcome of the models and associated compact remnants. Stars that avoid the pair instability supernova channel should produce black holes with masses ranging from ≈40 to ≈1000 M ⊙. In particular, stars with initial masses of about 100 M ⊙ could leave black holes of ≃85–90 M ⊙, values consistent with the estimated primary black hole mass of the GW190521 merger event. Overall, these results may contribute to explaining future data from next-generation gravitational-wave detectors, such as the Einstein Telescope and Cosmic Explorer, which will have access to an as-yet-unexplored black hole mass range of ≈102–104 M ⊙ in the early universe.

Adding gamma-ray polarimetry to the multi-messenger era

Context. The last decade has seen the emergence of two new fields within astrophysics: gamma-ray polarimetry and gravitational wave (GW) astronomy. The former, which aims to measure the polarization of gamma rays in the energy range of tens to hundreds of keV, from astrophysical sources, saw the launch of the first dedicated polarimeters such as GAP and POLAR. Due to both a large scientific interest as well as their large signal-to-noise ratios, gamma-ray bursts (GRBs) are the primary source of interest of the first generation of polarimeters. Polarization measurements are theorized to provide a unique probe of the mechanisms at play in these extreme phenomena. On the other hand, GW astronomy started with the detection of the first black hole mergers by LIGO in 2015, followed by the first multi-messenger detection in 2017. Aims. While the potential of the two individual fields has been discussed in detail in the literature, the potential for joint observations has thus far been ignored. In this article, we aim to define how GW observations can best contribute to gamma-ray polarimetry and study the scientific potential of joint analyses. In addition, we aim to provide predictions on feasibility of such joint measurements in the near future. Methods. We study which GW observables can be combined with measurements from gamma-ray polarimetry to improve the discriminating power regarding GRB emission models. We then provide forecasts for the joint detection capabilities of current and future GW detectors and polarimeters. Results. Our results show that by adding GW data to polarimetry, a single precise joint detection would allow for the majority of emission models to be ruled out. We show that in the coming years, joint detections between GW and gamma-ray polarimeters might already be possible. Although these would allow one to constrain part of the model space, the probability of highly constraining joint detections will remain small in the near future. However, the scientific merit held by even a single such measurement makes it important to pursue such an endeavour. Furthermore, we show that using the next generation of GW detectors, such as the Einstein Telescope, joint detections for which GW data can better complement the polarization data become possible.

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

The Einstein Telescope (ET) is going to bring a revolution for the future of multimessenger 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 a 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 (SGRBs). 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 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 localization 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 explore the 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.

Investigating the detection rates and inference of gravitational-wave and radio emission from black hole neutron star mergers

Context. Black hole neutron star (BHNS) mergers have recently been detected through their gravitational-wave (GW) emission. While no electromagnetic emission has yet been confidently associated with these systems, observing any such emission could provide information on, for example, the neutron star equation of state. Black hole neutron star mergers could produce electromagnetic emission as a short gamma-ray burst (sGRB) and/or an sGRB afterglow upon interaction with the circum-merger medium. Aims. We make predictions for the expected detection rates with the Square Kilometre Array Phase 1 (SKA1) of sGRB radio afterglows associated with BHNS mergers. We also investigate the benefits of a multi-messenger analysis in inferring the properties of the merging binary. Methods. We simulated a population of BHNS mergers, making use of recent stellar population synthesis results, and estimated their sGRB afterglow flux to obtain the detection rates with SKA1. We investigate how this rate depends on the GW detector sensitivity, the primary black hole spin, and the neutron star equation of state. We then performed a multi-messenger Bayesian inference study on a fiducial BHNS merger. We simulated its sGRB afterglow and GW emission as input to this study, using recent models for both, and take systematic errors into account. Results. The expected rates of a combined GW and radio detection with the current-generation GW detectors are likely low. Due to the much increased sensitivity of future GW detectors such as the Einstein Telescope, the chances of an sGRB localisation and radio detection increase substantially. The unknown distribution of the black hole spin has a big influence on the detection rates, however, and it is a large source of uncertainty. Furthermore, when placing our fiducial BHNS merger at 50 and 100 Mpc, we are able to infer both the binary source parameters and the parameters of the sGRB afterglow simultaneously if we combine the GW and radio data. The radio data provide useful extra information on the binary parameters, such as the mass ratio, but this is limited by the systematic errors involved. For our fiducial binary at 200 Mpc, it is considerably more difficult to adequately infer the parameters of the system. Conclusions. The probability of finding an sGRB afterglow of a BHNS merger is low in the near future but will rise significantly when the next-generation GW detectors come online. Combining information from GW data with radio data is crucial for characterising the jet properties. A better understanding of the systematics will further increase the amount of information on the binary parameters that can be extracted from this radio data.

Constraining High-redshift Stellar-mass Primordial Black Holes with Next-generation Ground-based Gravitational-wave Detectors

The possible existence of primordial black holes in the stellar-mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population III stars, are expected to dominate at high redshifts (z ≳ 10). However, the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET) can access this distinctive feature in the merger rates as functions of redshift, allowing for direct measurement of the abundance of the two populations and hence for robust constraints on the abundance of primordial black holes. We simulate four months’ worth of data observed by a CE-ET detector network and perform hierarchical Bayesian analysis to recover the merger rate densities. We find that if the universe has no primordial black holes with masses of , the projected upper limit on their abundance f PBH as a fraction of dark matter energy density may be as low as , about two orders of magnitude lower than the current upper limits in this mass range. If instead f PBH ≳ 10−4, future gravitational-wave observations would exclude f PBH = 0 at the 95% credible interval.

Gravitational-wave Emission from a Primordial Black Hole Inspiraling inside a Compact Star: A Novel Probe for Dense Matter Equation of State

Abstract Primordial black holes of planetary masses captured by compact stars are widely studied to constrain their composition fraction of dark matter. Such a capture may lead to an inspiral process and be detected through gravitational-wave signals. In this Letter, we study the postcapture inspiral process by considering two different kinds of compact stars, i.e., strange stars and neutron stars. The dynamical equations are numerically solved, and the gravitational-wave emission is calculated. It is found that the Advanced LIGO can detect the inspiraling of a 10−5 M ⊙ primordial black hole at a distance of 10 kpc, while a Jovian-mass case can even be detected at megaparsecs. Promisingly, the next generation of gravitational-wave detectors can detect cases of 10−5 M ⊙ primordial black holes up to ∼1Mpc and Jovian-mass cases at several hundred megaparsecs. Moreover, the kilohertz gravitational-wave signal shows significant differences for strange stars and neutron stars, potentially making it a novel probe to the dense matter equation of state.

Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes

Our Galaxy and the nearby Andromeda galaxy (M 31) are the most massive members of the Local Group, and they seem to be a bound pair, despite the uncertainties on the relative motion of the two galaxies. A number of studies have shown that the two galaxies will likely undergo a close approach in the next 4−5 Gyr. We used direct N-body simulations to model this interaction to shed light on the future of the Milky Way – Andromeda system and for the first time explore the fate of the two supermassive black holes (SMBHs) that are located at their centers. We investigated how the uncertainties on the relative motion of the two galaxies, linked with the initial velocities and the density of the diffuse environment in which they move, affect the estimate of the time they need to merge and form “Milkomeda”. After the galaxy merger, we follow the evolution of their two SMBHs up to their close pairing and fusion. Upon the fiducial set of parameters, we find that Milky Way and Andromeda will have their closest approach in the next 4.3 Gyr and merge over a span of 10 Gyr. Although the time of the first encounter is consistent with other predictions, we find that the merger occurs later than previously estimated. We also show that the two SMBHs will spiral in the inner region of Milkomeda and coalesce in less than 16.6 Myr after the merger of the two galaxies. Finally, we evaluate the gravitational-wave emission caused by the inspiral of the SMBHs, and we discuss the detectability of similar SMBH mergers in the nearby Universe (z ≤ 2) through next-generation gravitational-wave detectors.