IIAP Publications

Memory effects and entanglement dynamics of finite time acceleration

Wed, 15 Apr 2026 00:00:00 GMT

Memory effects and entanglement dynamics of finite time acceleration Dubey, Nitesh K; Kolekar, Sanved We construct a smooth trajectory in Minkowski spacetime that is inertial in the asymptotic past and future but undergoes approximately uniform acceleration for a finite duration. In a suitable limit, this trajectory reduces to the standard Rindler trajectory, reproducing the expected Bogoliubov transformations and results consistent with the thermal time hypothesis. We analyze the behavior of an Unruh-DeWitt (UDW) detector following such a trajectory and explore the dependence of complete positivity (CP) divisibility on the detector’s frequency, acceleration, and the duration of acceleration. Notably, we find that the detector exhibits a memory effect due to the finite duration of acceleration, which is also quantified by the Fisher information. We further examine two UDW detectors along various trajectory combinations and show that, unlike the transition rate, both the total correlation and the entanglement harvested return smoothly to their initial values after the acceleration/deceleration phase. These correlation measures behave similarly in both accelerating and decelerating segments. Interestingly, we do not observe any measurable effect of the memory effect on negativity or mutual information. We also discuss the physical significance of the sign of the flux of acceleration-induced radiation. Open Access

Probing departures from ΛCDM by late-time datasets

Wed, 01 Apr 2026 00:00:00 GMT

Probing departures from ΛCDM by late-time datasets Chaudhary, Himanshu; Sharma, Vipin Kumar; Capozziello, Salvatore; Mustafa, Ghulam Observational data play a pivotal role in identifying cosmological models that are both theoretically consistent and empirically viable. In this work, we investigate the level of preference for dynamical dark energy over a cosmological constant using current late-time observational datasets, including cosmic chronometers (CC), baryon acoustic oscillations from Dark Energy Spectroscopic Instrument (DESI) DR2, and different Type Ia supernova catalogs (Pantheon+, DES-Dovekie, Union3). We analyze various dynamical dark-energy models, including ωCDM, oωCDM, ω0ωaCDM, logarithmic, exponential, Jassal–Bagla–Padmanabhan (JBP), Barboza– Alcaniz (BA), and GEDE. In most cases, the oΛCDM and oωCDM models favor an open Universe. For the oωCDM, the inclusion of DES-Dovekie or Union3 data together with CC and DESI DR2 favors a nearly flat geometry. Using the CC + DESI DR2 dataset, the preference for dynamical dark energy lies between the 1σ and 2σ level. When different supernova catalogs (DES-Dovekie or Union3) are included, the deviation from ΛCDM in the ωCDM, ω0ωaCDM, logarithmic, JBP, BA, and GEDE models increases to the 2σ–2.74σ level, while the Pantheon+ sample yields deviations below the 2σ level. We find consistent evidence for ω0 > −1 and ωa < 0 across all dark-energy models, indicating a preference for dynamical dark energy characterized by a Quintom B-type scenario. The ΛCDM paradigm has long served as the standard framework of modern cosmology; however, recent DESI DR2 results have exposed emerging tensions with the cosmological constant Λ, hinting at possible new physics in the dark-energy sector. Even so, the currently available data are still not strong enough to definitively rule out the ΛCDM model. Open Access; Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Non-Gaussian expansion of Minkowski tensors in redshift space

Mon, 20 Apr 2026 00:00:00 GMT

Non-Gaussian expansion of Minkowski tensors in redshift space Appleby, S; Pichon, C; Pravabati, C; Pogosyan, Dmitri; Park, C This paper focuses on extending the use of Minkowski tensors to analyze anisotropic signals in cosmological data, focusing on those introduced by redshift space distortions. We derive the ensemble average of the two translationinvariant, rank-2 Minkowski tensors (W1 0,2 and W2 0,2) for a matter density field that is perturbatively non-Gaussian in redshift space. This is achieved through the Edgeworth expansion of the joint probability density function of the field and its derivatives, expressing the ensemble averages in terms of cumulants up to cubic order. Our goal is to connect these theoretical predictions to the underlying cosmological parameters, allowing for parameter estimation by measuring them from galaxy surveys. The work builds on previous analyses of Minkowski functionals in both real and redshift space and addresses the effects of Finger-of-God velocity dispersion and shot noise. We validate our predictions by matching them to measurements of the Minkowski tensors from dark matter simulation data, finding that perturbation theory is a qualified success. Nonperturbative Finger-of-God effects remain significant at relatively large scales of RG ≲ 20 h−1 Mpc and are particularly pronounced in the components parallel to the line of sight. Open Access; Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

The evolution of the reconnection flux during the eruption of magnetic flux ropes

Wed, 01 Apr 2026 00:00:00 GMT

The evolution of the reconnection flux during the eruption of magnetic flux ropes Maity, Samriddhi Sankar; Chatterjee, Piyali; Sarkar, Ranadeep; Mytheen, Ijas S Coronal mass ejections (CMEs) are powerful drivers of space weather, with magnetic flux ropes (MFRs) widely regarded as their primary precursors. However, the variation in the reconnection (RC) flux during the evolution of MFRs during CME eruptions remains poorly understood. In this paper, we develop a 3D magnetohydrodynamic (MHD) model that we use to explore the temporal evolution of the RC flux during the MFR evolution using both numerical simulations and observational data. Our initial coronal configuration features an isothermal atmosphere and a potential arcade magnetic field beneath which an MFR emerges at the lower boundary. As the MFR rises, we observe significant stretching and compression of the overlying magnetic field beneath it. Magnetic RC begins with the gradual formation of a current sheet, eventually culminating with the impulsive expulsion of the flux rope. We analyze the temporal evolution of RC fluxes during two successive MFR eruptions while continuously emerging the twisted flux rope through the lower boundary. We also conduct a similar analysis using observational data from the Helioseismic and Magnetic Imager and the Atmospheric Imaging Assembly for an eruptive event. Comparing our MHD simulation with observational data, we find that RC flux play a crucial role in the determination of CME kinematics. From the onset to the eruption, the rate of RC shows a monotonic variation with the acceleration. This simulation of a solar eruption provides important insights into the complex dynamics of CME initiation and progression. Open Access; Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.