arXiv subjects

Ayodeji Ibitoye

Publications and source records attributed to Ayodeji Ibitoye.

13 recordsLinked to original sources

arXiv2026

Observational constraints on a damped harmonic oscillator model of dark energy

We constrain a damped harmonic oscillator (DHO) dark-energy equation of state using the full cosmic microwave background (CMB) likelihoods in combination with DESI BAO and three distinct Type Ia supernova compilations: Pantheon+, DES-Dovekie, and Union3. The equation of state obeys a second-order damped oscillator equation in number of $e$-folds, so that its frequency $f$, damping rate $b$, and equilibrium value $w_{\rm m}$ fully specify the late-time dynamics. The model exhibits oscillatory behavior only at low redshifts, around the equilibrium value $w=-1$, with distinct characteristics for the different supernova compilations: an underdamped solution for DES-Dovekie and Union3, and an overdamped solution for Pantheon+. At higher redshifts, the model closely mimics $\Lambda$CDM and deviates significantly only at $z<0.6$, with the magnitude of the deviation depending on the supernova compilation. We further identify a region of the $(f,b)$ parameter space, corresponding to rapid variation of the equation of state at low redshift, in which the perturbation equations become numerically stiff and cannot be integrated with a canonical dark-energy sound speed i.e., $c_s^2 =1$. We show that reducing the rest-frame sound speed removes this obstruction while leaving the observables unchanged at the $10^{-3}$ level, and therefore treat it as a numerical prescription rather than a physical modification of the model. The model yields $H_0 = 67.53^{+1.22}_{-1.18}$ km/s/Mpc for Pantheon+, $H_0 = 69.08^{+1.23}_{-1.16}$ km/s/Mpc for DES-Dovekie, and $H_0 = 70.67^{+1.89}_{-1.87}$ km/s/Mpc for Union3. The present-day equation-of-state parameter is constrained to $w_0 = -0.521^{+0.891}_{-0.414}$, $-3.01^{+1.14}_{-1.21}$, and $-3.16^{+1.11}_{-1.16}$ for Pantheon+, DES-Dovekie, and Union3, respectively.

astro-ph.CO↗

arXiv2026

Constraining primordial non-Gaussianity and energy injection with the thermal Sunyaev-Zeldovich effect and integrated Sachs-Wolfe effect cross-correlation

Constraining primordial non-Gaussianity (PNG) provides key insights into the physics of cosmic inflation and the initial conditions of the Universe, which remain central topics in cosmology. In this study, we use the cross-correlation between the integrated Sachs-Wolfe (ISW) effect and the thermal Sunyaev-Zeldovich (tSZ) effect derived from Ibitoye et al. (2024) to jointly constrain PNG and early-Universe energy injection, including the standard intergalactic medium contribution. For scale-independent PNG we obtain $f_{\rm NL} = -358^{+140}_{-114}$ ($68\%$~C.L.). For a scale-dependent model ($f_{\rm NL}=f_{\rm NL}^{0}(\ell/\ell_{0})^{n_{\rm NL}}$, with $\ell_{0}=200$), we find $f^{0}_{\rm NL} = -296^{+173}_{-157}$ and $n_{\rm NL} = 0.62^{+1.02}_{-0.64}$, both consistent with Gaussian initial conditions. We also constrain the early-Universe energy injection amplitude to be $\alpha_{\rm inj} = -3.93^{+1.34}_{-0.99}$, with uncertainty reduced by a factor of $\sim\!2.6$ if Planck 2018 $f_{\rm NL}$ constraint is applied as a prior. Future surveys such as Simons Observatory and Euclid will tighten these constraints further. Complementary to conventional probes, this work provides the first ISW-tSZ constraint on exotic energy injection and enables precision tests of early-Universe physics while probing late-time gravitational potential and thermal energy perturbations.

astro-ph.CO↗

arXiv2026

21 cm Power Spectrum Analysis of North Celestial Pole Observations with the Tianlai Dish Pathfinder Array

The Tianlai Dish Pathfinder Array (TDPA) is a radio interferometer designed to test techniques for 21 cm intensity mapping in the post-reionization universe as a means of measuring large-scale cosmic structure. Using 9 nights of observations targeting the North Celestial Pole (NCP) field, totaling approximately 107 hours of integration time, we analyze data in the frequency range 700-800 MHz (corresponding to redshift $z \sim 0.9$). We do the data format conversion, radio frequency interference (RFI) flagging, calibration, imaging and point source subtraction, and foreground removal via Singular Value Decomposition (SVD). The spherically averaged power spectrum $\Delta^2(k)$ is obtained. This work successfully establishes and validates a comprehensive data analysis framework for the TDPA. We identify key improvements including sky model refinement, increased integration time, and pipeline optimization that will enable future detection of the 21 cm signal through auto-correlation and cross-correlation with optical galaxy surveys.

astro-ph.IM↗

arXiv2026

The Hydrostatic Mass Bias and the $\sigma_8$ Tension: A Multi-Probe Forecast for Stage-IV/V Surveys

The hydrostatic mass bias ($b_{\mathrm{HSE}}$) is a leading systematic uncertainty in cluster cosmology and a principal source of degeneracy with $\sigma_8$ and $\Omega_m$. We investigate the capability of Stage-IV CMB and optical surveys to calibrate $b_{\mathrm{HSE}}$ using tomographic cross-correlations between the thermal Sunyaev--Zel'dovich (tSZ) effect, galaxy clustering, and weak lensing. We perform a Fisher forecast incorporating realistic survey noise, foreground modeling for clustered CIB and radio sources, and full marginalization over cosmological and astrophysical nuisance parameters, including per-bin galaxy bias perturbations, photometric redshift shifts, intrinsic alignments, and baryonic feedback modeled with HMCode2020. With optimized tomographic binning (10 lens and 5 source bins for LSST; 6 lens and 5 source bins for CSST), we forecast marginalized constraints of $0.98\%$ for SO+LSST, $1.60\%$ for CMB-S4+LSST, and $2.40\%$ for CMB-S4+CSST. Tomography improves $b_{\mathrm{HSE}}$ precision by factors of approximately three relative to non-tomographic analyses, reflecting the role of redshift information in breaking the $b_{\mathrm{HSE}}$--$\sigma_8$ degeneracy. Optical-only probes provide no direct constraint on $b_{\mathrm{HSE}}$, whereas inclusion of tSZ-containing spectra enables percent-level calibration under realistic systematic assumptions. The results demonstrate that multi-probe tomographic analyses with Stage-IV surveys can achieve robust control of hydrostatic mass bias, strengthening cluster-based constraints on structure growth.

astro-ph.CO↗

arXiv2026

Constraining Quintessence Models with ISW-tSZ Cross-Correlations: A Comparative Analysis of Thawing, Tracker, and Scaling-Freezing Dynamics

We present constraints on quintessence dark energy models using the observational detection of the Integrated Sachs-Wolfe (ISW)--thermal Sunyaev-Zeldovich (tSZ) cross-correlation dataset. Our analysis compares three classes of quintessence dynamics: thawing, tracker, and scaling-freezing with the standard $\Lambda$CDM cosmology. Through a comprehensive likelihood analysis, we derive best-fit values and 68\% confidence intervals for key cosmological parameters, finding $\Omega_{\rm m} = 0.322^{+0.027}_{-0.030}$ and $\sigma_8 = 0.735^{+0.045}_{-0.035}$ for $\Lambda$CDM, with deviations in alternative models consistent within $1\sigma$. For the thawing model, we consider an exponential potential with slope $\lambda = 0.736^{+0.270}_{-0.227}$, while for the tracker and scaling-freezing models, we use inverse axion-like and double exponential potentials, respectively. Observationally, the tracker model yields $n = 5.651^{+1.625}_{-1.604}$ and $f = 0.258^{+0.149}_{-0.096}$, and the scaling-freezing model gives $\lambda_1 = 0.405^{+0.293}_{-0.322}$ and $\lambda_2 = 23.226^{+7.975}_{-7.258}$. The dimensionless tSZ amplitude ($\widetilde{W}^{\rm SZ}$) and cosmic infrared background (CIB) parameters are tightly constrained across all models, providing additional insights into astrophysical foregrounds. Our results demonstrate the effectiveness of ISW--tSZ cross-correlations as a probe of dark energy dynamics, with the Thawing quintessence model yielding the lowest $\chi^2_{\rm min}$ among the tested scenarios, and highlight the need for future high-precision measurements to distinguish between quintessence models and $\Lambda$CDM.

astro-ph.CO↗

arXiv2025

AI Agent for Source Finding by SoFiA-2 for SKA-SDC2

Source extraction is crucial in analyzing data from next-generation, large-scale sky surveys in radio bands, such as the Square Kilometre Array (SKA). Several source extraction programs, including SoFiA and Aegean, have been developed to address this challenge. However, finding optimal parameter configurations when applying these programs to real observations is non-trivial. For example, the outcomes of SoFiA intensely depend on several key parameters across its preconditioning, source-finding, and reliability-filtering modules. To address this issue, we propose a framework to automatically optimize these parameters using an AI agent based on a state-of-the-art reinforcement learning (RL) algorithm, i.e., Soft Actor-Critic (SAC). The SKA Science Data Challenge 2 (SDC2) dataset is utilized to assess the feasibility and reliability of this framework. The AI agent interacts with the environment by adjusting parameters based on the feedback from the SDC2 score defined by the SDC2 Team, progressively learning to select parameter sets that yield improved performance. After sufficient training, the AI agent can automatically identify an optimal parameter configuration that outperform the benchmark set by Team SoFiA within only 100 evaluation steps and with reduced time consumption. Our approach could address similar problems requiring complex parameter tuning, beyond radio band surveys and source extraction. Yet, high-quality training sets containing representative observations and catalogs of ground truth are essential.

cs.LG↗

arXiv2025

GalaxyGenius: Mock galaxy image generator for various telescopes from hydrodynamical simulations

We introduce GalaxyGenius, a Python package designed to produce synthetic galaxy images tailored to different telescopes based on hydrodynamical simulations. Its implementation will support and advance research on galaxies in the era of large-scale sky surveys. The package comprises three main modules: data preprocessing, ideal data cube generation, and mock observation. Specifically, the preprocessing module extracts necessary properties of star and gas particles for a selected subhalo from hydrodynamical simulations and creates the execution file for the following radiative transfer procedure. Subsequently, building on the above information, the ideal data cube generation module executes a widely used radiative transfer project, specifically the SKIRT, to perform the SED assignment for each particle and the radiative transfer procedure to produce an IFU-like ideal data cube. Lastly, the mock observation module takes the ideal data cube and applies the throughputs of aiming telescopes, while also incorporating the relevant instrumental effects, point spread functions (PSFs), and background noise to generate the required mock observational images of galaxies. To showcase the outcomes of GalaxyGenius, we created a series of mock images of galaxies based on the IllustrisTNG and EAGLE simulations for both space and ground-based surveys, spanning ultraviolet (UV) to infrared (IR) wavelength coverage, including CSST, Euclid, HST, JWST, Roman, and HSC. GalaxyGenius offers a flexible framework to generate mock galaxy images with customizable recipes. These generated images can serve as valuable references for verifying and validating new approaches in astronomical research. They can also serve as training sets for relevant studies using deep learning in cases where real observational data are insufficient.

astro-ph.IM↗

arXiv2024

Investigating the Behavior and Spatiotemporal Variations of Green Line Emission in the Solar Corona

Understanding coronal structure and dynamics can be facilitated by analyzing green-line emission, which enables the investigation of diverse coronal structures such as coronal loops, streamers, coronal holes, and various eruptions in the solar atmosphere. In this study, we investigated the spatiotemporal behaviors of green-line emissions in both low and high latitudes across nine solar cycles, ranging from cycle 17 to the current cycle 25, using the Modified Homogeneous Data Set (MHDS). We employed methodologies such as cross-correlation, power spectral density (PSD), and wavelet transform techniques for this analysis. We found distinct behaviors in green line energy across various latitudinal distributions in the solar atmosphere. The trends observed at higher latitudes differ from those at lower latitudes. The emission behaviors show a close association with other solar phenomena like solar flares, sunspots, and coronal mass ejections (CMEs) throughout the solar cycles. The observed variations exhibit harmonic periods. The emission activity is significantly higher in the low latitudes, accounting for over 70 percent of the emissions, while the higher latitudes contribute less than 30 percent. The emissions exhibit asymmetric behavior between the northern and southern hemispheres, leading to a 44-year cycle of solar hemispheric dominance shifts. Various factors, such as Alfv\'en waves, solar magnetic fields, sunspots, differential rotation, and reconnection events, influence the observed differences in behavior between lower and higher latitudes, suggesting the existence of potential underlying phenomena contributing to deviations in properties, intensity, temporal dynamics, and spatiotemporal lifetime.

astro-ph.SR↗

arXiv2024

HI Intensity Mapping cross-correlation with thermal SZ fluctuations: forecasted cosmological parameters estimation for FAST and Planck

The 21 cm emission from neutral hydrogen surveys holds great potential as a valuable method for exploring the large-scale structure of the Universe. In this paper, we forecast for the cross-correlation between the Thermal Sunyaev-Zel'dovich (SZ) fluctuations as probed by the Planck satellite, and fluctuations in the HI brightness temperature as probed by the ground-based Five-hundred-meter Aperture Spherical Telescope (FAST), to trace the connection between galaxy clusters and the HI large-scale structure. Assuming that the measurement is limited by instrumental noise rather than by foreground, we estimate the potential detectability of the cross-correlation signal and their improvement in the measurement of the HI cosmic density, the hydrostatic mass bias parameter, and the universal pressure profile (UPP) parameters. We obtain a constraint on the cosmic neutral hydrogen density parameter significantly to $\sigma(\Omega_{\rm HI}) = 1.0 \times 10^{-6}$. We also find that the average halo masses contributing to the ${{\rm HI}-y}$ cross-power spectrum in the one-halo regime is $\sim 1.5\times 10^{14} M_{\odot}$. Our results also show that the HI-SZ cross-correlation has great potential to probe the distribution of neutral hydrogen (HI) within halos at low redshift.

astro-ph.CO↗

arXiv2024

Exploring cosmological constraints of the weak gravitational lensing and galaxy clustering joint analysis in the CSST photometric survey

We explore the joint weak lensing and galaxy clustering analysis from the photometric survey operated by the China Space Station Telescope (CSST), and study the strength of the cosmological constraints. We employ a high-resolution JiuTian-1G simulation to construct a partial-sky light cone to $z=3$ covering 100 deg$^2$, and obtain the CSST galaxy mock samples based on an improved semi-analytical model. We perform a multi-lens-plane algorithm to generate corresponding synthetic weak lensing maps and catalogs. Then we generate the mock data based on these catalogs considering the instrumental and observational effects of the CSST, and use the Markov Chain Monte Carlo (MCMC) method to perform the constraints. The covariance matrix includes non-Gaussian contributions and super-sample covariance terms, and the systematics from intrinsic alignments, galaxy bias, photometric redshift uncertainties, shear calibration, and non-linear effects are considered in the analysis. We find that the constraint result is comparable to that from Stage III surveys, and it can be significantly improved further in the full CSST survey with 17500 deg$^2$. This indicates the CSST photometric survey is powerful for exploring the Universe.

astro-ph.CO↗

arXiv2023

Cross-correlation between the thermal Sunyaev-Zeldovich effect and the Integrated Sachs-Wolfe effect

We present a joint cosmological analysis of the power spectra measurement of the Planck Compton parameter and the integrated Sachs-Wolfe (ISW) maps. We detect the statistical correlation between the Planck Thermal Sunyaev-Zeldovich (tSZ) map and ISW data with a significance of a $3.6\sigma$ confidence level~(CL), with the autocorrelation of the Planck tSZ data being measured at a $25 \sigma$ CL. The joint auto- and cross-power spectra constrain the matter density to be $\Omega_{\rm m}= 0.317^{+0.040}_{-0.031}$, the Hubble constant $H_{0}=66.5^{+2.0}_{-1.9}\,{\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$ and the rms matter density fluctuations to be $\sigma_{8}=0.730^{+0.040}_{-0.037}$ at the 68% CL. The derived large-scale structure $S_{8}$ parameter is $S_8 \equiv \sigma_{8}(\Omega_{\rm m}/0.3)^{0.5} = 0.755\pm{0.060} $. If using only the diagonal blocks of covariance matrices, the Hubble constant becomes $H_{0}=69.7^{+2.0}_{-1.5}\,{\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$. In addition, we obtain the constraint of the product of the gas bias, gas temperature, and density as $b_{\rm gas} \left(T_{\rm e}/(0.1\,{\rm keV}) \right ) \left(\bar{n}_{\rm e}/1\,{\rm m}^{-3} \right) = 3.09^{+0.320}_{-0.380}$. We find that this constraint leads to an estimate on the electron temperature today as $T_{\rm e}=(2.40^{+0.250}_{-0.300}) \times 10^{6} \,{\rm K}$, consistent with the expected temperature of the warm-hot intergalactic medium. Our studies show that the ISW-tSZ cross-correlation is capable of probing the properties of the large-scale diffuse gas.

astro-ph.CO↗

arXiv2022

Cross Correlation between the Thermal Sunyaev-Zel'dovich Effect and Projected Galaxy Density Field

We present a joint analysis of the power spectra of the Planck Compton $y$-parameter map and the projected galaxy density field using the Wide Field Infrared Survey Explorer (WISE) all-sky survey. We detect the statistical correlation between WISE and Planck data (g$y$) with a significance of $21.8\,\sigma$. We also measure the auto-correlation spectrum for the tSZ ($yy$) and the galaxy density field maps (gg) with a significance of $150\,\sigma$ and $88\,\sigma$, respectively. We then construct a halo model and use the measured correlations $C^{\rm gg}_{\ell}$, $C^{yy}_{\ell}$ and $C^{{\rm g}y}_{\ell}$ to constrain the tSZ mass bias $B\equiv M_{500}/M^{\rm tSZ}_{500}$. We also fit for the galaxy bias, which is included with explicit redshift and multipole dependencies as $b_{\rm g}(z,\ell)=b_{\rm g}^0(1+z)^{\alpha}(\ell/\ell_0)^{\beta}$, with $\ell_0=117$. We obtain the constraints to be $B =1.50{\pm 0.07}\,(\textrm{stat}) \pm{0.34}\,(\textrm{sys})$, i.e. $1-b_{\rm H}=0.67\pm 0.03\,({\rm stat})\pm 0.16\,({\rm sys})$ (68\% confidence level) for the hydrostatic mass bias, and $b_{\rm g}^0=1.28^{+0.03}_{-0.04}\,(\textrm{stat}) \pm{0.11}\,(\textrm{sys})$, with $\alpha=0.20^{+0.11}_{-0.07}\,(\textrm{stat}) \pm{0.10}\,(\textrm{sys})$ and $\beta=0.45{\pm 0.01}\,(\textrm{stat}) \pm{0.02}\,(\textrm{sys})$ for the galaxy bias. Incoming data sets from future CMB and galaxy surveys (e.g. Rubin Observatory) will allow probing the large-scale gas distribution in more detail.

astro-ph.CO↗

arXiv2022

Snowmass2021 Cosmic Frontier: Cosmic Microwave Background Measurements White Paper

This is a solicited whitepaper for the Snowmass 2021 community planning exercise. The paper focuses on measurements and science with the Cosmic Microwave Background (CMB). The CMB is foundational to our understanding of modern physics and continues to be a powerful tool driving our understanding of cosmology and particle physics. In this paper, we outline the broad and unique impact of CMB science for the High Energy Cosmic Frontier in the upcoming decade. We also describe the progression of ground-based CMB experiments, which shows that the community is prepared to develop the key capabilities and facilities needed to achieve these transformative CMB measurements.

astro-ph.CO↗