Future Gravitational Wave Detectors Research Articles

Quasinormal modes in noncommutative Schwarzschild black holes

We investigate the quasinormal modes of a massless scalar field in a Schwarzschild black hole, which is deformed due to noncommutative corrections. We introduce the deformed Schwarzschild black hole solution, which depends on the noncommutative parameter Θ. We then extract the master equation as a Schrödinger-like equation, giving the explicit expression of the effective potential which is modified due to the noncommutative corrections. After that, we solve the master equation numerically. The significance of these results is twofold. Firstly, our results can be related to the detection of gravitational waves by the near future gravitational wave detectors, such as LISA, which will have a significantly increased accuracy. In particular, these observed gravitational waves produced by binary strong gravitational systems have oscillating modes which can provide valuable information. Secondly, our results can serve as an additional tool to test the predictions of GR, as well as to examine the possible detection of this kind of gravitational corrections.

Correlated 0.01–40 Hz seismic and Newtonian noise and its impact on future gravitational-wave detectors

Correlated 0.01–40 Hz seismic and Newtonian noise and its impact on future gravitational-wave detectors

Probing primordial black holes at high redshift with future gravitational wave detectors

Abstract We analyze the detection prospects for potential Primordial Black Hole Binary (PBHB) populations buried in the Stellar-Origin Black Hole Binary (SOBHB) population inferred by the LVK collaboration. We consider different PBHB population scenarios and several future Gravitational Wave (GW) detectors. To separate the PBHB component from the SOBHB one, we exploit the prediction that the PBHB merger rate does not decline as fast as the SOBHB one at high redshift. However, only a tiny fraction of PBHB events may be resolved individually, and the sub-threshold events may yield an undetectable Stochastic GW Background (SGWB). For this reason, we determine the statistical significance of the PBHB contributions in the number of resolvable events seen in future Earth-based detectors and the SGWB measured at LISA. We quantify them in the limit that SOBHB population uncertainties are small, as one may optimistically expect at the time that future detectors will operate. In general, we find the synergy between these probes will consistently help assess whether or not a sizeable PBHB population is present.

Non-stoichiometric silicon nitride for future gravitational wave detectors

Silicon nitride thin films were deposited at room temperature employing a custom ion beam deposition (IBD) system. The stoichiometry of these films was tuned by controlling the nitrogen gas flow through the ion source and a process gas ring. A correlation is established between the process parameters, such as ion beam voltage and ion current, and the optical and mechanical properties of the films based on post-deposition heat treatment. The results show that with increasing heat treatment temperature, the mechanical loss of these materials as well as their optical absorption decreases producing films with an extinction coefficient as low as k=6.2(±0.5)×10−7 at 1064 nm for samples annealed at 900 ∘C. This presents the lowest value for IBD SiN x within the context of gravitational wave detector applications. The mechanical loss of the films was measured to be ϕ=2.1(±0.6)×10−4 once annealed post deposition to 900 ∘C.

Model-independent Way to Determine the Hubble Constant and the Curvature from the Phase Shift of Gravitational Waves with DECIGO

In this Letter, we propose a model-independent method to determine the Hubble constant and curvature simultaneously by taking advantage of the possibilities of future spaceborne gravitational-wave detector DECIGO in combination with the radio quasars as standard rulers. Similarly to the redshift drift in the electromagnetic domain, accelerating expansion of the Universe causes a characteristic phase correction to the gravitational waveform detectable by DECIGO. Hence, one would be able to extract the Hubble parameter H(z). This could be used to recover a distance–redshift relation supported by the data not relying on any specific cosmological model. Assuming the FLRW metric and using intermediate-luminosity radio quasars as standard rulers, one achieves an interesting opportunity to directly assess the H 0 and Ω k parameters. To test this method, we simulated a set of acceleration parameters achievable by future DECIGO. Based on the existing sample of 120 intermediate-luminosity radio quasars calibrated as standard rulers, we simulated much bigger samples of such standard rulers possible to obtain with very long baseline interferometry (VLBI). In the case of (N = 100) of radio quasars, which is the size of the currently available sample, the precision of the cosmological parameters determined would be σH0=2.74 km s−1 Mpc−1 and σΩk=0.175 . In the optimistic scenario (N = 1000) achievable by VLBI, the precision of H 0 would be improved to 1%, which is comparable to the result of σH0=0.54 km s−1 Mpc−1 from Planck 2018 TT, TE, EE+lowE+lensing data, and the precision of Ω k would be 0.050. Our results demonstrate that such combined analysis, possible in the future, could be helpful in solving the current cosmological issues concerning the Hubble tension and cosmic curvature tension.

Detectability of stochastic gravitational wave background from weakly hyperbolic encounters

We compute the stochastic gravitational wave (GW) background generated by black hole–black hole (BH–BH) hyperbolic encounters with eccentricities close to one and compare them with the respective sensitivity curves of planned GW detectors. We use the Keplerian potential to model the orbits of the encounters and the quadrupole formula to compute the emitted GWs. We take into account hyperbolic encounters that take place in clusters up to redshift 5 and with BH masses spanning from 5 M⊙ to 55 M⊙. We assume the clusters to be virialized and study several cluster models with different mass and virial velocity, and finally obtain an accumulative result, displaying the background as an average. Using the maxima and minima of our accumulative result for each frequency, we provide analytical expressions for both optimistic and pessimistic scenarios. Our results suggest that the background from these encounters is likely to be detected by the third-generation detectors Cosmic explorer and Einstein telescope, while the tail section at lower frequencies intersects with DECIGO, making it a potential target source for both ground- and space-based future GW detectors.

Absolute Ranging with Time Delay Interferometry for Space-Borne Gravitational Wave Detection.

In future space-borne gravitational wave (GW) detectors, time delay interferometry (TDI) will be utilized to reduce the overwhelming noise, including the laser frequency noise and the clock noise etc., by time shifting and recombining the data streams in post-processing. The successful operation of TDI relies on absolute inter-satellite ranging with meter-level precision. In this work, we numerically and experimentally demonstrate a strategy for inter-satellite distance measurement. The distances can be coarsely determined using the technique of arm-locking ranging with a large non-ambiguity range, and subsequently TDI can be used for precise distance measurement (TDI ranging) by finding the minimum value of the power of the residual noises. The measurement principle is introduced. We carry out the numerical simulations, and the results show millimeter-level precision. Further, we perform the experimental verifications based on the fiber link, and the distances can be measured with better than 0.05 m uncertainty, which can well satisfy the requirement of time delay interferometry.

MEMS miniaturized low-noise magnetic field sensor for the observation of sub-millihertz magnetic fluctuations in space exploration

The objective of this paper is to show that, using magnetic field modulation with a MEMS resonator, it is possible to reduce the noise floor of a commercial Tunneling Magnetic Resistance by one order of magnitude, in the ultra-low frequency range. Low noise at this frequency range is a strong requirement in planetary or space exploration missions like LISA (Laser Interferometer Space Antenna), where the observed gravitational waves will be in the 0.1 mHz to 0.1 Hz range. It will be shown that the noise spectral amplitude after demodulation from 0.1 mHz to 100 mHz is well below the 100 nT/Hz requirement for the future space-borne gravitational wave detector LISA – that we take as reference – being at 20 nT/Hz at 0.1 mHz, and reaching an average 1.5nT/Hz at higher frequencies, from 100 mHz to 1 Hz.

Probing a magnetar origin for the population of extragalactic fast X-ray transients detected by Chandra

Context. Twenty-two extragalactic fast X-ray transients (FXTs) have now been discovered from two decades of Chandra data (analyzing ∼259 Ms of data), with 17 associated with distant galaxies (≳100 Mpc). Different mechanisms and progenitors have been proposed to explain their properties; nevertheless, after analyzing their timing, spectral parameters, host-galaxy properties, luminosity function, and volumetric rates, their nature remains uncertain. Aims. We interpret a sub-sample of nine FXTs that show a plateau or a fast-rise light curve within the framework of a binary neutron star (BNS) merger magnetar model. Methods. We fit their light curves and derive magnetar (magnetic field and initial rotational period) and ejecta (ejecta mass and opacity) parameters. This model predicts two zones: an orientation-dependent free zone (where the magnetar spin-down X-ray photons escape freely to the observer) and a trapped zone (where the X-ray photons are initially obscured and only escape freely once the ejecta material becomes optically thin). We argue that six FXTs show properties consistent with the free zone and three FXTs with the trapped zone. Results. This sub-sample of FXTs has a similar distribution of magnetic fields and initial rotation periods to those inferred for short gamma-ray bursts, suggesting a possible association. We compare the predicted ejecta emission fed by the magnetar emission (called merger-nova) to the optical and near-infrared upper limits of two FXTs, XRT 141001 and XRT 210423 where contemporaneous optical observations are available. The non-detections place lower limits on the redshifts of XRT 141001 and XRT 210423 of z ≳ 1.5 and ≳0.1, respectively. Conclusions. If the magnetar remnants lose energy via gravitational waves (GWs), it should be possible to detect similar objects with the current advanced LIGO detectors out to a redshift z ≲ 0.03, while future GW detectors will be able to detect them out to z ≈ 0.5.

Likelihood of white dwarf binaries to dominate the astrophysical gravitational wave background in the mHz band

Context. The astrophysical gravitational wave background (AGWB) is a collective signal of astrophysical gravitational wave sources dominated by compact binaries. One key science goal of current and future gravitational wave detectors is to obtain its measurement. Aims. We aim to determine the population of compact binaries dominating the AGWB in the mHz band. We revisit and update an earlier work by Farmer & Phinney (2003, MNRAS, 346, 1197) to model the astrophysical gravitational wave background sourced by extragalactic white dwarf binaries in the mHz frequency band. Methods. We calculated the signal using a single-metallicity model for the white dwarf population in the Universe using the global star formation history. Results. We estimate the white dwarf AGWB amplitude to be ∼60% higher than the earlier estimate. We also find that the overall shape of the white dwarf AGWB shows a good fit with a broken power law combined with an exponential cut-off. Conclusions. We compare our results to present-day best estimates for the background due to black hole and neutron star binaries, finding that the white dwarf component is likely to dominate in the mHz band. We provide an order-of-magnitude estimate that explains this hierarchy and we comment on the implications for future missions that aim to detect the AGWB. We also note that the black hole AGWB may only be detectable at high frequency. We outline several improvements that can be made to our estimate, however, these points are unlikely to change our main conclusion, which posits that the white dwarf AGWB dominates the mHz band.

Formation of Merging Stellar-mass Black Hole Binaries by Gravitational-wave Emission in Active Galactic Nucleus Disks

Many stellar-mass black holes (sBHs) are expected to orbit supermassive black holes at galactic centers. For galaxies with active galactic nuclei, it is likely that the sBHs reside in a disk. We study the formation of sBH binaries via gravitational-wave emission in such disks. We examine analytically the dynamics of two sBHs orbiting a supermassive black hole, estimate the capture cross section, and derive the eccentricity distribution of bound binaries at different frequency bands. We find that the majority of the merging sBH binaries, assembled in this manner, can be measured as highly eccentric, detectable in the LIGO-Virgo-KAGRA (LVK) band from their formation, with (1 − e) ≪ 1, through their circularization and up to their merger; the remaining binaries circularize to small eccentricities (e ≲ 0.3) before entering the LVK band. More eccentric mergers would be observed for sBHs with higher random velocities, closer to the supermassive black hole, or at lower observing frequency bands, as planned in future gravitational-wave detectors such as the Einstein Telescope and LISA.

Resolving Phase Transition Properties of Dense Matter through Tidal-excited g-mode from Inspiralling Neutron Stars

The investigation of the phase state of dense matter is hindered by complications of first-principle nonperturbative quantum chromodynamics. By performing the first consistent general-relativistic calculations of tidal-excited g-mode of neutron stars with a first-order strong interaction phase transition in the high-density core, we demonstrate that the gravitational-wave signal during binary neutron star inspiral probes their innermost hadron-quark transition and provides potent constraints from present and future gravitational-wave detectors.

Phase transitions and gravitational waves in a model of ℤ3 scalar dark matter

Theories with more than one scalar field often exhibit phase transitions producing potentially detectable gravitational wave (GW) signal. In this work we study the semi-annihilating ℤ3 dark matter model, whose dark sector comprises an inert doublet and a complex singlet, and assess its prospects in future GW detectors. Without imposing limits from requirement of providing a viable dark matter candidate, i.e. taking into account only other experimental and theoretical constraints, we find that the first order phase transition in this model can be strong enough to lead to a detectable signal. However, direct detection and the dark matter thermal relic density constraint calculated with the state-of-the-art method including the impact of early kinetic decoupling, very strongly limit the parameter space of the model explaining all of dark matter and providing observable GW peak amplitude. Extending the analysis to underabundant dark matter thus reveals region with detectable GWs from a single-step or multi-step phase transition.

Swarm Intelligence Methods for Extreme Mass Ratio Inspiral Search: First Application of Particle Swarm Optimization

Swarm intelligence (SI) methods are nature-inspired metaheuristics for global optimization that exploit a coordinated stochastic search strategy by a group of agents. Particle swarm optimization (PSO) is an established SI method that has been applied successfully to the optimization of rugged high-dimensional likelihood functions, a problem that represents the main bottleneck across a variety of gravitational wave (GW) data analysis challenges. We present results from the first application of PSO to one of the most difficult of these challenges, namely the search for the Extreme Mass Ratio Inspiral (EMRI) in data from future spaceborne GW detectors such as LISA, Taiji, or Tianqin. We use the standard Generalized Likelihood Ratio Test formalism, with the minimal use of restrictive approximations, to search 6 months of simulated LISA data and quantify the search depth, signal-to-noise ratio (SNR), and breadth, within the ranges of the EMRI parameters, that PSO can handle. Our results demonstrate that a PSO-based EMRI search is successful for a search region ranging over ≳10σ for the majority of parameters and ≳200σ for one, with σ being the SNR-dependent Cramer–Rao lower bound on the parameter estimation error and 30≤SNR≤50. This is in the vicinity of the search ranges that the current hierarchical schemes can identify. Directions for future improvement, including computational bottlenecks to be overcome, are identified.

Primordial black holes dark matter and secondary gravitational waves from warm Higgs-G inflation

We explore the role of dissipative effects during warm inflation leading to the small-scale enhancement of the power spectrum of curvature perturbations. In this paper, we specifically focus on non-canonical warm inflationary scenarios and study a model of warm Higgs-G inflation, in which the Standard Model Higgs boson drives inflation, with a Galileon-like non-linear kinetic term. We show that in the Galileon-dominated regime, the primordial power spectrum is strongly enhanced, leading to the formation of primordial black holes (PBH) with a wide range of the mass spectrum. Interestingly, PBHs in the asteroid mass window ∼ (1017–1023) g are generated in this model, which can explain the total abundance of dark matter in the Universe. In our analysis, we also calculate the secondary gravitational waves (GW) sourced by these small-scale overdense fluctuations and find that the induced GW spectrum can be detected in future GW detectors, such as LISA, BBO, DECIGO, etc. Our scenario thus provides a novel way of generating PBHs as dark matter and a detectable stochastic GW background from warm inflation. We also show that our scenario is consistent with the swampland and the trans-Planckian censorship conjectures and, thus, remains in the viable landscape of UV complete theories.

Probing exotic phases via stochastic gravitational wave spectra

Abstract Stochastic backgrounds of gravitational waves (GWs) from the pre-BBN era offer a unique opportunity to probe the universe beyond what has already been achieved with the Cosmic Microwave Background (CMB). If the source is short in duration, the low frequency tail of the resulting GW spectrum follows a universal frequency scaling dependent on the equation of state of the universe when modes enter the horizon. We demonstrate that the distortion of the equation of state due to massive particles becoming non-relativistic can lead to an observable dip in the GW spectrum. To illustrate this effect, we consider a first order chiral symmetry breaking phase transition in the weak-confined Standard Model (WCSM). The model features a large number of pions and mostly elementary fermions with masses just below the critical temperature for the phase transition. These states lead to a 20% dip in the GW power. We find potential sensitivity to the distortions in the spectrum to future GW detectors such as LISA, DECIGO, BBO, and μAres.

Supercooling in radiative symmetry breaking: theory extensions, gravitational wave detection and primordial black holes

First-order phase transitions, which take place when the symmetries are predominantly broken (and masses are then generated) through radiative corrections, produce observable gravitational waves and primordial black holes. We provide a model-independent approach that is valid for large-enough supercooling to quantitatively describe these phenomena in terms of few parameters, which are computable once the model is specified. The validity of a previously-proposed approach of this sort is extended here to a larger class of theories. Among other things, we identify regions of the parameter space that correspond to the background of gravitational waves recently detected by pulsar timing arrays (NANOGrav, CPTA, EPTA, PPTA) and others that are either excluded by the observing runs of LIGO and Virgo or within the reach of future gravitational wave detectors. Furthermore, we find regions of the parameter space where primordial black holes produced by large over-densities due to such phase transitions can account for dark matter. Finally, it is shown how this model-independent approach can be applied to specific cases, including a phenomenological completion of the Standard Model with right-handed neutrinos and gauged B - L undergoing radiative symmetry breaking.

TIC 378898110: A bright, short-period AM CVn binary in TESS

ABSTRACT AM CVn-type systems are ultracompact, helium-accreting binary systems that are evolutionarily linked to the progenitors of thermonuclear supernovae and are expected to be strong Galactic sources of gravitational waves detectable to upcoming space-based interferometers. AM CVn binaries with orbital periods ≲20–23 min exist in a constant high state with a permanently ionized accretion disc. We present the discovery of TIC 378898110, a bright (G = 14.3 mag), nearby (309.3 ± 1.8 pc), high-state AM CVn binary discovered in TESS two-minute-cadence photometry. At optical wavelengths, this is the third-brightest AM CVn binary known. The photometry of the system shows a 23.07172(6) min periodicity, which is likely to be the ‘superhump’ period and implies an orbital period in the range 22–23 min. There is no detectable spectroscopic variability. The system underwent an unusual, year-long brightening event during which the dominant photometric period changed to a shorter period (constrained to 20.5 ± 2.0 min), which we suggest may be evidence for the onset of disc-edge eclipses. The estimated mass transfer rate, $\log (\dot{M} / \mathrm{M_\odot } \, \mathrm{yr}^{-1}) = -6.8 \pm 1.0$, is unusually high and may suggest a high-mass or thermally inflated donor. The binary is detected as an X-ray source, with a flux of $9.2 ^{+4.2}_{-1.8} \times 10^{-13}$ erg cm−2 s−1 in the 0.3–10 keV range. TIC 378898110 is the shortest-period binary system discovered with TESS, and its large predicted gravitational-wave amplitude makes it a compelling verification binary for future space-based gravitational wave detectors.

Erratum: Detecting cosmological gravitational wave background after removal of compact binary coalescences in future gravitational wave detectors [Phys. Rev. D 107 , 064048 (2023)

Erratum: Detecting cosmological gravitational wave background after removal of compact binary coalescences in future gravitational wave detectors [Phys. Rev. D <b>107</b> , 064048 (2023)

The evolutionary route to form planetary nebulae with central neutron star–white dwarf binary systems

ABSTRACT We present a possible evolutionary pathway to form planetary nebulae (PNe) with close neutron star (NS)–white dwarf (WD) binary central stars. By employing the binary population synthesis technique, we find that the evolution involves two common envelope evolution (CEE) phases and a core collapse supernova explosion between them that forms the NS. Later the lower mass star engulfs the NS as it becomes a red giant, a process that leads to the second CEE phase and to the ejection of the envelope. This leaves a hot horizontal branch star that evolves to become a helium WD and an expanding nebula. Both the WD and the NS power the nebula. The NS in addition might power a pulsar wind nebula inside the expanding PN. From our simulations we find that the Galactic formation rate of NS–WD PNe is $1.8 \times 10^{-5}\, {\rm yr}^{-1}$ while the Galactic formation rate of all PNe is $0.42 \, {\rm yr}^{-1}$. There is a possibility that one of the observed Galactic PNe might be a NS–WD PN, and a few NS–WD PNe might exist in the Galaxy. The central binary systems might be sources for future gravitational wave detectors like LISA, and possibly of electromagnetic telescopes.