Publications (22)
Effects of a local physics change on the SH0ES determination of
Ruchika, Leandros Perivolaropoulos, Alessandro Melchiorri
The Hubble tension, a significant discrepancy between the Hubble constant () values derived from early-time (Cosmic Microwave Background and Baryon Acoustic Oscillations) and…
Observational Constraints on Axion(s) Dark Energy with a Cosmological Constant
Ruchika, Shahnawaz A. Adil, Koushik Dutta +2
The present work deals with a dark energy model that has an oscillating scalar field potential along with a cosmological constant (CC). The oscillating part of the potential repres…
A gravitational constant transition within cepheids as supernovae calibrators can solve the Hubble tension
Ruchika, Himansh Rathore, Shouvik Roy Choudhury +1
Local universe measurements of the Hubble constant (H0) using SNe Ia with Cepheids as calibrators yield a value of H0 which is in tension with the value inferred from the CMB and o…
Cosmological constraints and standard sirens forecasts for non-dynamical dark energy in Horndeski gravity
Marcello Miranda, Ruchika, Ivan De Martino +2
We investigate an analytically tractable sector of the Extended Cuscuton model, a non-dynamical dark-energy realization within the framework of viable Horndeski gravity. We focus o…
Bayesian Evidences for Dark Energy models in light of current obsevational data
Anto. I. Lonappan, Sumit Kumar, Ruchika +2
We do a comprehensive study of the Bayesian evidences for a large number of dark energy models using a combination of latest cosmological data from SNIa, CMB, BAO, Strong lensing t…
Coupled Quintessence scalar field model in light of observational datasets
Trupti Patil, Ruchika, Sukanta Panda
We do a detailed analysis of a well-theoretically motivated interacting dark energy scalar field model with a time-varying interaction term. Using current cosmological datasets fro…
Low-redshift estimates of the absolute scale of baryon acoustic oscillations
Thais Lemos, Ruchika, Joel C. Carvalho +1
Measurements of the characteristic length scale of the baryon acoustic oscillations (BAO) provide a robust determination of the distance-redshift relation. Currently, the bes…
Model independent constraints on dark energy evolution from low-redshift observations
Salvatore Capozziello, Ruchika, Anjan A Sen
Knowing the late time evolution of the Universe and finding out the causes for this evolution are the important challenges of modern cosmology. In this work, we adopt a model-indep…
Revisiting Gaussian Process Reconstruction for Cosmological Inference: The Generalised GP (Gen GP) Framework
Ruchika, Purba Mukherjee, Arianna Favale
We investigate uncertainties in the estimation of the Hubble constant () arising from Gaussian Process (GP) reconstruction, demonstrating that the choice of kernel introduces…
The Price of Shifting the Hubble Constant
Jarah Evslin, Anjan A Sen, Ruchika
An anisotropic measurement of the baryon acoustic oscillation (BAO) feature fixes the product of the Hubble constant and the acoustic scale . Therefore, regardless of the…
Is there an early Universe solution to Hubble tension?
Chethan Krishnan, Eoin à Colgáin, Ruchika +3
We consider a low redshift cosmological dataset comprising megamasers, cosmic chronometers, type Ia SNe and BAO, which we bin according to their redshift. For each bin, w…
Resilience and implications of adiabatic CMB cooling
Ruchika, William Giarè, Elsa M. Teixeira +1
We investigate potential deviations from the standard adiabatic evolution of the cosmic microwave background (CMB) temperature, , using the latest Sunyaev-Zeldovich…
Hubble Tension and the G-step Model: Re-examination of Recent Constraints on Modified Local Physics
Leandros Perivolaropoulos, Ruchika
We critically examine recent claims challenging the viability of the G-step model (GSM) as a solution to the Hubble tension. The GSM proposes a 4 % increase in the effective…
Dynamics of interacting scalar field model in the realm of chiral cosmology
Trupti Patil, Sukanta Panda, Manabendra Sharma +1
The strange behaviour of the universe's dark sector offers us the flexibility to address cosmological problems with different approaches. Using this flexibility, we consider a poss…
2D BAO vs 3D BAO: Hints for new physics?
Ruchika
As next-generation telescopes and observational surveys continue to expand the boundaries of our understanding, tensions and discrepancies between observational datasets are becomi…
A double take on early and interacting dark energy from JWST
Matteo Forconi, William Giarè, Olga Mena +4
The very first light captured by the James Webb Space Telescope (JWST) revealed a population of galaxies at very high redshifts more massive than expected in the canonical CDM…
Cosmology With Low-Redshift Observations: No Signal For New Physics
Koushik Dutta, Anirban Roy, Ruchika +2
We analyse various low-redshift cosmological data from Type-Ia Supernova, Baryon Acoustic Oscillations, Time-Delay measurements using Strong-Lensing, measurements using Cosm…
Optical depth to reionization in a Universe with multiple inhomogeneous domains
Shashank Shekhar Pandey, Ruchika, Subhadeep Mukherjee +1
We study the optical depth to reionization in a cosmological setting that includes backreaction from matter inhomogeneities, using the Buchert averaging formalism. We construct a s…
Beyond CDM with Low and High Redshift Data: Implications for Dark Energy
Koushik Dutta, Ruchika, Anirban Roy +2
Assuming that the Universe at higher redshifts (z \sim 4 and beyond) is consistent with LCDM model as constrained by the Planck measurements, we reanalyze the low redshift cosmolog…
Is it time to go beyond CDM universe?
Anto I. Lonappan, Ruchika, Anjan A Sen
Concordance CDM universe is the simplest model that is consistent with a large variety of cosmological observations till date. But few recent observations indicate inconsistenc…
Present Day Cosmic Acceleration from SDSS and DESI BAO: A Call for Finer Tomography of the DESI Bright Galaxy Survey
Anna Chiara Ferri, Ruchika, Alessandro Melchiorri
The DESI collaboration's Data Release~2 (DR2) provides baryon acoustic oscillation (BAO) measurements from over 14 million galaxies and quasars, and a joint analysis of DESI BAO, C…
Do the Early Galaxies observed by JWST disagree with Planck's CMB polarization measurements?
Matteo Forconi, Ruchika, Alessandro Melchiorri +2
The recent observations from the James Webb Space Telescope have led to a surprising discovery of a significant density of massive galaxies with masses of $M \ge 10^{10.5} M_{\odot…