The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

Moretti, F.; Bombacigno, Flavio; Montani, Giovanni

doi:10.3390/universe7120496

Cited by 11 publications

(7 citation statements)

References 169 publications

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“…The primordial black holes(PBH) are also studied as viable candidate for dark matter and the detection of GW signal emitted from such sources has been considered earlier [39][40][41][42][43]. In a different context concerning macroscopic gravity, the GW propagation dealing with modified dispersion relation and extra degrees of polarization in extended theories of gravity has been looked into in [44][45][46][47]. In this paper, we rather focus explicitly on DM condensate candidates that serve as constituent candidates for galactic DM halo.…”

Section: Jcap03(2023)041mentioning

confidence: 99%

Prospects of probing dark matter condensates with gravitational waves

Banerjee

Bera

Mota

2023

J. Cosmol. Astropart. Phys.

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The Lambda-Cold Dark Matter model explains cosmological observations most accurately till date. However, it is still plagued with various shortcomings at galactic scales. Models of dark matter such as superfluid dark matter, Bose-Einstein Condensate(BEC) dark matter and fuzzy dark matter have been proposed to overcome some of these drawbacks. In this work, we probe these models using the current constraint on the gravitational wave (GW) propagation speed coming from the binary neutron star GW170817 detection by LIGO-Virgo detector network and use it to study the allowed parameter space for these three models for Advanced LIGO+Virgo, LISA, IPTA and SKA detection frequencies. The speed of GW has been shown to depend upon the refractive index of the medium, which in turn, depends on the dark matter model parameters through the density profile of the galactic halo. We constrain the parameter space for these models using the bounds coming from GW speed measurement and the Milky Way radius bound. Our findings suggest that with Advanced LIGO-Virgo detector sensitivity, the three models considered here remain unconstrained. A meaningful constraint can only be obtained for detection frequencies ≤ 10-9 Hz, which falls in the detection range of radio telescopes such as IPTA and SKA. Considering this best possible case, we find that out of the three condensate models, the fuzzy dark matter model is the most feasible scenario to be falsified/validated in near future.

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Section: Jcap03(2023)041mentioning

confidence: 99%

Prospects of probing dark matter condensates with gravitational waves

Banerjee

Bera

Mota

2023

J. Cosmol. Astropart. Phys.

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“…General relativity (GR) predicts that only two tensor polarizations exist for the GW, the plus and cross modes. However, there are additional four polarizations allowed by the generic metric theories of gravity, including two vector modes and two scalar modes (Brans & Dicke 1961;Eardley et al 1973;Jacobson & Mattingly 2004;Sagi 2010;Liang et al 2017a;Moretti et al 2019Moretti et al , 2020Moretti et al , 2021. The observation of vector or scalar modes would cast doubt on general relatively, while their absence could be used to constrain modified gravity (Will 2014).…”

Section: Introductionmentioning

confidence: 99%

Testing the Polarization of Gravitational-wave Background with the LISA-TianQin Network

Hu,

Wang,

Tan

et al. 2024

ApJ

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While general relativity predicts only two tensor modes for gravitational-wave (GW) polarization, general metric theories of gravity allow for up to four additional modes, including two vector and two scalar modes. Observing the polarization modes of GWs could provide a direct test of the modified gravity. The stochastic GW background (SGWB), which can be detected by space-based laser-interferometric detectors at design sensitivity, will provide an opportunity to directly measure alternative polarization. In this paper, we investigate the performance of the LISA-TianQin network for detecting alternative polarizations of stochastic backgrounds, and propose a method to separate different polarization modes. First, we generalize the small antenna approximation to compute the overlap reduction functions for the SGWB with arbitrary polarization, which is suitable for any time-delay interferometry combination. Then we analyze the detection capability of LISA-TianQin for the SGWB with different polarizations. Based on the orbital characteristics of LISA-TianQin, we propose a method to distinguish different polarization modes from their mixed data. Finally, simulation tests are performed to verify the effectiveness of the method. The results of the simulations demonstrate that LISA-TianQin, when employing our proposed method, has the ability to differentiate between various polarization modes, with a specific emphasis on the ability to distinguish between the breathing and longitudinal modes.

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“…In particular, we speak of velocity birefringence when waves with left and right handed polarizations [59] propagate with different speeds, while in the presence of a different friction term for the two modes we have amplitude birefringence, in which the enhancement or suppression of the wave depends on its chiral state. Furthermore, when propagation within a material medium is also considered, it can be demonstrated that velocity birefringence can generate amplitude birefringence through the Landau damping phenomenon [60], consisting in the kinematic damping of gravitational waves in the absence of collisions (see [61][62][63][64][65][66][67][68][69][70][71][72] for more details). Gravitational wave birefringence is a well-established result of metric CSMG [23,[73][74][75], and in this work we show for the first time how such a phenomenon is present also in the metric-affine formulation.…”

Section: Introductionmentioning

confidence: 99%

Torsional birefringence in metric-affine Chern-Simons gravity: gravitational waves in late-time cosmology

Boudet¹,

Bombacigno²,

Moretti³

et al. 2022

Preprint

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In the context of the metric-affine Chern-Simons gravity endowed with projective invariance, we derive analytical solutions for torsion and nonmetricity in the homogeneous and isotropic cosmological case, described by a flat Friedmann-Robertson-Walker metric. We describe in some details the general properties of the cosmological solutions in the presence of a perfect fluid, such as dynamical stability and the settling of big bounce points, and we discuss the structure of some specific solutions reproducing de Sitter and power law behaviours for the scale factor. Then, we focus on first-order perturbations in the de Sitter scenario, and we study the propagation of gravitational waves in the adiabatic limit, looking at tensor and scalar polarizations. In particular, we find that metric tensor modes couple to torsion tensor components, leading to the appearance, as in the metric version of Chern-Simons gravity, of birefringence, described by different dispersion relations for the left and right circularized polarization states. As a result, the purely tensor part of torsion propagates like a wave, while nonmetricity decouples and behaves like a harmonic oscillator. Finally, we discuss scalar modes, outlining as they decay exponentially in time and do not propagate.

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The Role of Longitudinal Polarizations in Horndeski and Macroscopic Gravity: Introducing Gravitational Plasmas

Cited by 11 publications

References 169 publications

Prospects of probing dark matter condensates with gravitational waves

Prospects of probing dark matter condensates with gravitational waves

Testing the Polarization of Gravitational-wave Background with the LISA-TianQin Network

Torsional birefringence in metric-affine Chern-Simons gravity: gravitational waves in late-time cosmology

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