arXiv subjects

Oem Trivedi

Publications and source records attributed to Oem Trivedi.

At least 19 recordsLinked to original sources

arXiv2026

Dark Matter-Baryon Separability Predicts the Dynamics of an Almost-Dark Galaxy

We extend the Dark Matter-Baryon Separability Condition to show that the same framework developed for dark matter deficient galaxies naturally admits a conjugate branch describing preferential baryonic depletion. Using the recently discovered almost-dark galaxy TTT J1237327+143535 as a worked example, we derive a family of dynamical consistency relations parameterized by the unknown progenitor ratio $\mu_i$, including thresholds for $\sigma_{\rm los}$, $M_{\rm dyn}$, the enclosed baryonic fraction and the dynamical mass to light ratio. We further connect the separability framework to the expected globular cluster population, providing an independent consistency test of the inferred halo mass. We also provide some bounds on the baryon ratio using the tidal properties of Virgo Cluster. Future measurements of stellar kinematics, gas content and globular clusters can therefore determine whether this galaxy occupies the positive separability branch and also test whether dark matter deficient and baryon depleted systems can be described within a common framework.

astro-ph.CO↗

arXiv2026

Dark Energy in the $w-c_s^2$ Plane

We introduce a unified framework for dark energy diagnostics based on the joint phase space of the equation of state $w$ and the sound speed $c_s^2$. The resulting $w-c_s^2$ plane provides a minimal extension beyond background cosmology, capturing both the expansion history and perturbative properties within a single representation. Building on this framework, we define the microphysical flow parameter $F=dc_s^2/dw$, which encodes the dynamical relation between background evolution and perturbative response. We derive a direct connection between the present-day value $F_0$, $H_0$, and $\sigma_8$, and show that the microphysical flow parameter enables a hierarchy of increasingly stringent consistency tests that substantially reduce the viable dark energy theory space. We further demonstrate how trajectories in the $w-c_s^2$ plane distinguish models that are nearly degenerate at the level of $w(a)$, including canonical quintessence, Chaplygin gas models, and noncanonical scalar field realizations. This framework provides a compact phenomenological bridge between dark energy microphysics and future perturbation-sensitive observations, establishing $F_0$ as a useful discriminator of the kinetic structure underlying cosmic acceleration.

astro-ph.CO↗

arXiv2026

Dark Matter Deficient Galaxies as Probes of Dark Matter

Dark matter deficient galaxies provide a direct way to test whether baryons and dark matter can become sufficiently separated during galaxy evolution. We formulate a Dark Matter-Baryon Separability condition based on the relative incorporation efficiencies of the two components, requiring the final dark matter to baryon ratio to fall below an observationally defined threshold. Applied to high speed collisions, this condition constrains dark matter baryon momentum transfer cross section, interacting dark matter fraction and the efficiency of gravitational recapture. The same framework gives us bounds on the abundance and cooling time of dissipative dark matter, and on the integrated escape rate of ultralight fuzzy dark matter from shallow or tidally disturbed potentials. These results show how dark matter deficient galaxies can complement cosmological and laboratory probes by constraining late time dark matter interactions, dissipation and halo stability.

gr-qc↗

arXiv2026

Solar System Probes for Scalar Field Dark Matter

Scalar field dark matter provides us with a well motivated alternative to conventional particle dark matter, especially when ultralight fields form coherent oscillations or compact self gravitating clumps. Here we develop three complementary Solar System and local Galactic level probes of such models. These probes pertain to ADAF-like flares from scalar clump encounters with Kuiper Belt Objects, atomic clock searches for oscillatory variations of fundamental constants and astrometric microlensing by compact scalar clumps. We derive simple sensitivity estimates and null detection bounds on the scalar clump fraction, clock couplings and compact lens abundance. Our results show that Gaia-like astrometry can probe compact scalar clumps at the percent level near $M_s\gtrsim10^{-2}M_\odot$, while future astrometric and clock experiments can extend the reach to lower masses and weaker couplings.

astro-ph.CO↗

arXiv2026

Solar System and Atomic Clock Bounds on Locally Coupled Swampland Scalars

We study how local measurements constrain light scalar fields that are relevant in late time cosmic acceleration and are often discussed in connection with swampland criteria. Starting from a scalar-tensor framework, we define the swampland slope and curvature variables in the canonically normalized Einstein frame and relate them to Solar System tracking, Lunar Laser Ranging, equivalence principle tests and atomic clock comparisons. These measurements do not constrain the scalar velocity by itself, but products of that velocity with microscopic couplings to matter, gravity and atomic parameters. For coupling directions visible to local experiments, the scalar is driven into an ultra slow present regime. This severely restricts the possibility of realizing an $\mathcal{O}(1)$ de Sitter gradient through unscreened visible sector couplings alone. The refined de Sitter alternative remains possible, but in the single field hilltop realization it requires proximity to the maximum or a tuned suppression of the growing mode.

physics.gen-ph↗

arXiv2026

Nonlinear Dynamical Regimes of Cosmological Frequency Combs

We study the emergence of Cosmological Frequency Combs (CFCs) in a quintessence cosmology with an exponential potential using a dynamical systems formulation. Expressing the evolution equations in expansion-normalized variables yields an autonomous nonlinear system that supports time-periodic attractors corresponding to limit cycles, producing comb like spectral structures in cosmological observables without external periodic forcing. Numerical simulations reveal transitions between single frequency, comb like and chaotic regimes controlled by the fundamental frequency, background equation of state parameter, and initial conditions. Coherent comb structures arise only within well defined dynamical windows, while very low frequencies and unfavorable initial conditions suppress phase locking. These results show that CFCs naturally emerge from nonlinear cosmological dynamics and motivate further study of their possible observational implications.

astro-ph.CO↗

arXiv2026

Non-Markovian Memory-Induced Effects in Quantum Cosmology

We study memory effects in quantum cosmology by extending the semiclassical Wheeler-DeWitt framework beyond its usual local form. The main idea is to introduce a causal memory kernel at sub leading order, rather than imposing fractional derivatives directly by hand. In this setting, fractional time evolution appears as an effective description of the underlying nonlocal dynamics. We apply the framework to cosmological perturbations in de Sitter space and find a correction to the primordial power spectrum with a characteristic $k^{3/4}$ scaling. This contribution mainly affects high $l$ CMB temperature anisotropies, in contrast with standard semiclassical quantum gravitational corrections, which are strongest at large angular scales. We also discuss how the same memory-dependent dynamics may affect primordial non-Gaussianity, producing scale dependent corrections to the bispectrum and possible deviations from the usual squeezed limit consistency relation. Since the memory coefficient controls short scale power, it may also influence structure formation and could require some tuning in order to give phenomenologically acceptable astrophysical environments. Finally, we suggest that a cyclic extension of the Hawking-Hartle no-boundary proposal may provide a setting in which the effective memory strength can evolve across successive cosmological histories. In this way, the framework gives a concrete realization of fractional quantum cosmology based on memory effects and also points to possible observational signatures of nonlocal quantum gravitational dynamics.

gr-qc↗

arXiv2026

Testing Supersymmetric Hidden Sectors with Long-Baseline Atom Interferometers

Atomic interferometry provides a sensitive near Earth probe of high energy physics through precision measurements of quantum phase. In this Letter, we point out that MAGIS and AION like long-baseline atom interferometers can also be used to test supersymmetric hidden sectors, if these sectors contain ultralight moduli, dilatons or hidden scalars that induce coherent phase oscillations. In such a setup, the measured atomic phase does not only constrain an effective phenomenological scalar coupling. It can be related to derivatives of supersymmetric gauge kinetic functions, K\"ahler metrics, Yukawa couplings, Higgs sector parameters and the QCD scale along light hidden sector directions. We derive the mapping from a generic SUSY/SUGRA modulus to the effective atom interferometric coupling, and show that future phase sensitivities may probe very small visible sector admixtures of otherwise hidden fields. This identifies MAGIS/AION type experiments as non-collider probes of supersymmetric and string-motivated infrared relics, complementary to gravitational wave, astrophysical and collider searches.

hep-ph↗

arXiv2026

Apocalypse When? Solar System Constraints on an Imminent Big Rip

Phantom dark energy models with an equation of state parameter $w < -1$ lead generically to a future big rip singularity, in which the dark energy density becomes infinite in a finite time. Current limits on dark energy constrain $w$ to be close to $-1$, and if $w$ is assumed constant, then a future big rip cannot occur in less than the order of a Hubble time in the future. However, many models allow $w$ to decrease rapidly with time. In that case, or if one assumes an additional phantom component with current energy density far below the dark energy density and $w << -1$, it is possible to achieve an imminent big rip, which we define to be a future singularity occuring in much less than the Hubble time. Such a possibility cannot be constrained by any cosmological measurements, as these are all based on light emitted billions of years in the past. Indeed, it is not possible, on the basis of cosmological observations, to rule out a future big rip tomorrow. However, solar system dynamics are sensitive to the behavior of phantom dark energy on timescales of decades rather than billions of years. Using solar system measurements, we are able to derive limits on the timescale for a future big rip independent of the dynamics of the phantom component. We obtain $t_{rip} - t_0 > 30$ years. While admittedly a poor limit, these results are likely to be improved by future more precise measurements of solar system dynamics. Our results also show that evidence for an imminent big rip would show up first in solar system data, rather than in any cosmological observation.

astro-ph.CO↗

arXiv2026

Unique Gravitational-Wave Signals from Negative-Mass Binaries

Negative masses have long been explored, but their observational viability remains unclear. In this work, we develop a unified, observationally testable framework to constrain negative masses using both coupling level and dynamical probes. We establish that while dipole radiation bounds require universality of gravitational charge, the intrinsic dynamics of negative mass binaries generically lead to anomalous behaviors such as anti-chirps, dispersal and runaway motion. These signatures are absent in current gravitational wave observations, providing a robust exclusion channel independent of modified gravity assumptions.

gr-qc↗

arXiv2026

Machine Learning for Multi-messenger Probes of New Physics and Cosmology: A Review and Perspective

The multi-messenger exploration of dark matter and physics beyond the Standard Model has emerged as a central direction in modern astro-particle physics, particularly following the discovery of gravitational waves. In this work, we present a comprehensive review and forward-looking perspective on machine-learning-enhanced multi-messenger approaches, combining information from gravitational waves, cosmic rays, gamma rays, neutrinos, and collider experiments. We summarize the current state of the field, discuss recent methodological developments, and outline a coherent research program aimed at integrating heterogeneous datasets within a unified inference framework. Our collaboration proposes here a plan for forthcoming analyses aiming at extracting information on the properties and interactions of dark matter, and finally on its genesis, combining multi-messenger astronomy techniques and inputs from laboratory physics. The main objectives planned in this line of research comprise: i) the multi-messenger analysis of new physics in cosmology, including mainly, but not only, several different models of dark matter; ii) the phenomenology of new physics signatures in ground-based cosmic rays experiments, with cross-correlation to the corresponding physical, astrophysical and cosmological observations; iii) the development of machine learning methods for data analysis in ground-based cosmic rays experiments, in light of the new physics signatures. We note that several groups have explored the use of multi-messenger observations, including gravitational waves, to probe alternative dark matter candidates. The present work builds on these developments by focusing on the role of machine learning in integrating heterogeneous datasets. We foresee that such a cross-fertilizing approach will represent the right path to extract information about the main questions left in fundamental physics.

hep-ph↗

arXiv2026

Smoking Gun Signatures of Quasilocal Probability in Black Hole Ringdowns

Building on recent work introducing the idea of Quasilocal Probability in curved spacetime, we develop its observational implications for black hole ringdown in detail. We show that horizon-induced probability flux leads to an effective non-Hermitian dynamics producing three distinctive signatures, which are correlated multi-mode deviations, weak amplitude dependence and a mismatch between waveform damping and energy accounting. These effects arise from a single boundary-flux mechanism and therefore exhibit a constrained, low-dimensional structure not expected in generic modified gravity scenarios. We demonstrate that while individual deviations may be mimicked, their combined pattern provides a robust discriminator of quasilocal probability. We further argue that upcoming gravitational wave observations can probe these signatures at meaningful precision. We also establish that black hole ringdown is a novel arena to test whether quantum mechanical Hermiticity is really a fundamental property or an emergent symmetry in quantum gravity.

gr-qc↗

arXiv2026

Thermodynamics vs Teleodynamics: A Cosmological Divide?

We show that stationary black holes and the evolving universe belong to fundamentally different thermodynamic regimes: black holes obey ordinary Bekenstein Hawking thermodynamics, whereas cosmology necessarily follows memory-bearing teleodynamics. We show that teleodynamics is not valid for black holes, but is unavoidable in an expanding cosmology. This provides a dynamical, semi-classical realization of the thermodynamic split conjecture and identifies memory accumulation as the natural source of deviations from the area law in cosmology. Our results suggest that quantum gravity should not seek to extrapolate black hole thermodynamics to the universe, but instead must incorporate horizon memory as a fundamental microscopic ingredient and consider cosmological constructions consistent with that.

gr-qc↗

arXiv2026

Does Gravity Render Probability Quasilocal?

We propose that probability in quantum theory, like energy in general relativity, acquires a fundamentally quasilocal character in curved spacetime. Interpreting Hermiticity as the symmetry associated with inner-product conservation, we show that gravitational boundaries and horizons convert global probability conservation into a flux balance law. The resulting quasilocal probability naturally induces effective non-Hermiticity for restricted observers while preserving global unitarity. We demonstrate this explicitly in Schwarzschild, Kerr and FLRW spacetimes and after this, we identify observational imprints in black hole ringdowns. Our results suggest that in quantum field theory on curved backgrounds, probability conservation is as geometrically conditioned as energy itself.

gr-qc↗

arXiv2026

Inflation and Primordial Perturbations in Fractal Cosmology

We study inflationary dynamics within the framework of fractal cosmology, where space is characterized by an effective non-integer dimension $D$. In our work, fractal effects are sourced through thermodynamic modifications at the cosmological horizon. Using the modified Friedmann and continuity equations, we then derive the modified slow roll parameter and their evolution for linear, cubic, Starobinsky ($R+R^2$) and Natural inflationary potentials, showing that the slow roll parameters get suppressed for $D<3$. We further derive a fractal extension of the Mukhanov-Sasaki equation by introducing an effective momentum $k_{\text{eff}}$, which captures the modification of spatial Laplacian due to fractality. This leads to explicit corrections to the scalar power spectrum and the spectral index $n_s$, depending on both $D$ and a fractional length scale $L$. Confrontation with Planck 2018 data constrains the effective dimension to a best-fit range of $2.7\lesssim D \lesssim 3$ for the Starobinsky model. Furthermore, in the case of Natural Inflation, fractal corrections relax the usual requirement of super-Planckian axion decay constants, opening a phenomenologically viable parameter space inaccessible in the standard $3+1$ dimensional cosmology.

gr-qc↗

arXiv2026

Probing Dark Energy on the Moon

The effective field theory (EFT) of cosmic acceleration provides a model-independent framework for describing dark energy and modified gravity, yet many of its defining operators remain weakly constrained by existing observations. We show that measurements of horizon-scale metric fluctuations with a lunar laser interferometer can directly probe the kinetic sector of the EFT of dark energy, enabling constraints on operators governing scalar perturbation dynamics rather than only the background expansion history. In particular, we demonstrate sensitivity to the EFT kinetic coefficient $M_2^4$ and the associated sound speed of dark energy, $c_s^2$. This establishes a qualitatively new observational handle on the microphysical consistency conditions of late-time acceleration models, allowing broad regions of EFT parameter space to be probed, constrained, or potentially discovered.

astro-ph.CO↗

arXiv2026

Non-Hermitian Quantum Mechanics with Applications to Gravity

Hermiticity is usually treated as a foundational axiom of quantum mechanics, guaranteeing real spectra and unitary time evolution. In this work we argue that Hermiticity is more naturally understood as a symmetry law arising from the global conservation of an inner product current. We show that in spacetimes admitting complete Cauchy surfaces without boundary flux this conservation reduces to the familiar Hermiticity condition of the canonical inner product. However, in the presence of causal horizons, most strikingly in black hole geometries, this conservation law becomes obstructed for restricted observers. Tracing over inaccessible degrees of freedom then inevitably yields completely positive trace preserving dynamics with an effective non-Hermitian generator. Using quantum thermodynamics and the monotonicity of relative entropy, we demonstrate that the generalized second law may be reinterpreted as an entropy balance that compensates precisely for the flux of inner product charge through the horizon. The structure of Einstein equations, through the Bianchi identity and the Raychaudhuri focusing equation, provides the geometric mechanism underlying this balance. We also show that black hole ringdown can serve as a realistic observational probe of this idea and may provide quantitative upper bounds on the strength of horizon-induced inner product flux. In this way gravity, entropy production, and effective non-Hermiticity are unified under a single structural principle, with Hermiticity emerging as the special case of globally conserved inner product symmetry.

gr-qc↗

arXiv2026

Game Theory in Cosmology

We present a game-theoretic statistical framework for cosmology, which we term \textit{Cosmological Teleodynamics}. We recast the dark sector, cosmic acceleration, large-scale structure, and cosmic tensions as emergent consequences of nonlocal memory and intrinsically persistent organization in a self-gravitating Universe. By introducing a maximum-caliber weight on cosmic histories and a bias functional encoding structural memory, we derive modified Friedmann, Boltzmann, and Poisson equations that naturally generate dark energy-like acceleration, dark matter-like clustering, and scale-dependent growth suppression. We also show how this approach can naturally help alleviate the $H_0$ and $S_8$ tensions, can produce anisotropic velocity fields, and predict environment-dependent halo signatures that cannot arise from particle dark matter or scalar-field dark energy. We also derive a generalized horizon entropy and temperature, revealing a nonequilibrium statistical origin for cosmic acceleration and formulating a Law of Universal Arbitrage Equilibrium that governs the evolution of the Universe, showing that it is expanding towards a continuous form of Nash equilibrium. Cosmological Teleodynamics therefore offers a unified, emergent, and testable alternative to the conventional dark sector, rooted not in new particles but in the intrinsic statistical and systemic structure of cosmic memory, and shows that the universe itself operates like a giant potential game.

astro-ph.CO↗