Conveners
Parallel - Cosmology: Session 1
- Pavan K Aluri
Parallel - Cosmology: Session 2
- There are no conveners in this block
Parallel - Cosmology: Session 3
- Pradyumn K Sahoo
The Reheating era of inflationary Universe can be parameterized by various parameters like reheating temperature $T_{\text{re}}$, reheating duration $N_{\text{re}}$ and average equation of state parameter $\overline{\omega }_{\text{re}}$, which can be constrained by observationally feasible values of scalar power spectral amplitude and spectral index. In our work, we have done the single...
Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon Acoustic Oscillations at low redshifts can potentially be probed by sensitive HI intensity mapping experiments and constrain the properties of dark energy....
I'll present the prospect of reconstructing the ''cosmic distance ladder'' of the Universe using our novel deep learning framework called LADDER - Learning Algorithm for Deep Distance Estimation and Reconstruction. LADDER was trained on the apparent magnitude data from the Pantheon Type Ia supernovae compilation, incorporating the full covariance information among data points, to produce...
In this work we present our analysis of one of the prominent "anomalies" of CMB sky, the "hemispherical power asymmetry (HPA)", from the latest fullsky CMB maps from Planck satellite mission's Public Release 4. The data is analyzed from various perspectives to understand the nature of HPA better viz., a re-estimation of the magnitude and direction of HPA and the corresponding significance,...
The cosmic web observed in the present universe is an intricate network of galaxies. According to the standard cosmological model, the tiny density fluctuations that existed in the early universe were gravitationally amplified, giving rise to the observable cosmic web or the large-scale structures. To enhance our comprehension of the cosmos and gain valuable insights on galactic evolution it...
In this presentattion, we offer the dynamical system analysis of the DBI (Dirac-Born-Infeld) scalar field in a modified f(Q) gravity context. We have taken a polynomial form of modified gravity and used two different kinds of scalar potential, i.e., polynomial and exponential, and found a closed autonomous dynamical system of equations. We have analyzed the fixed points of such a system and...
$\mathbb{Z}_3$ symmetric dark matter models have demonstrated remarkable potential in addressing various (astro-)particle physics challenges. In this presentation, I will discuss the diverse ways in which this model can successfully explain the different cosmological observations. We have considered two such promising models: semi-annihilating dark matter (SADM) and Co-SIMP $2\rightarrow 3$...
In the post-reionization universe ($z ≲ 6$), large-scale structure (LSS) is traced by dense, self-shielded clumps of neutral hydrogen (HI) within galaxies. Line-Intensity-Mapping of 21cm is an effective method to probe LSS and constrain cosmology. However, auto-clustering studies of HI are hampered by survey systematics, making HI detection challenging. Cross-correlation analysis between HI...
We do a detailed study on vortex formation in a magnetized plasma within the spacetime of a moving cosmic string using analytical and numerical methods. The conical spacetime around the cosmic string causes the frozen-in magnetic field to deform due to the fluid flow. We find that the overdensity in the wake region amplifies the magnetic field. This amplification depends on the direction and...
Magnetic fields in cosmic string wakes generate magnetohydrodynamic shock waves. The reletivistic charged particles in the wake will get accelerated and emit synchrotron radiation. We assume that the overall magnetic field is homogeneous over the width of the wake. Using a one-zone leptonic model, we obtain the sprectrum of synchrotron radiation emitted by these non-thermal relativistic...
A well-known method for generating a large blue spectral index for axionic isocurvature perturbations involves a flat direction without a quartic potential term for the axion field's radial partner. In this work, we demonstrate how a large blue spectral index can be achieved even with a quartic potential term linked to the Peccei-Quinn symmetry breaking radial partner. We utilize the fact that...
The natural inflation model with a periodic cosine potential is ruled out by recent Planck 2018 data for the decay constant $f \lesssim 5.5~M_{\rm Pl}$. If the Planck data is combined with the BICEP Keck array and BAO data, the model is excluded (at $2$-$\sigma$) for all values of $f$. In this context, we revisit the model when the pseudoscalar inflation $\phi$ is coupled with a gauge field...
Magnetic reconnection in the magnetized wakes of cosmic strings results in the release of a large amount of energy. This energy is released in a short period of time. In this work, we show that this sudden release of energy can result in a Gamma-Ray Burst (GRBs) of short duration. Since the magnetic reconnection occurs due to the shock collisions in the cosmic string wake, we use a modified...
One of the recently proposed machine learning techniques in image processing that surpasses (in some cases) the accuracy of a traditional Convolutional Neural network (CNN) is the Vision Transformer. In this technique, one divides an entire image into different patches and then uses a Transformer-like algorithm to understand different features of the image. For the first time, we use this...
This study investigates the impacts of both finite temperature and strong magnetic field on Anisotropic Deformed Magnetized White Dwarfs within the parameterized γ-metric formalism. We have considered a relativistic free Fermi gas of electrons embedded in strong quantizing magnetic fields and at finite temperatures. Due to the anisotropy in the pressures parallel and perpendicular to the...
Numerous observations on astrophysical and cosmological scales can be interpreted to mean that, in addition to the familiar kind of matter well described by the standard model of elementary particle physics, there exists Dark Matter (DM). The fundamental properties of the elementary particles which make up the DM e.g. particle mass, spin, couplings etc are currently being observationally...
The Vera C. Rubin Observatory Legacy Survey of Space and Time (Rubin LSST) is expected to achieve its first system light by late 2025. An initial data preview, drawn from early commissioning phases, is set for 2025-26, exciting the scientific community as they prepare to explore the Rubin LSST data. In this context, we have been working on developing the DESC Time Domain (TD) pipeline with a...
Black Hole is a region of space time where the gravity is strong enough that, there is no predictable connection between the interior and the exterior region. A Kerr black hole can be explained only in terms of mass, spin and angular momentum. LQG is completely non-perturbative, explicit background independent approach to quantum gravity theories. Generally, the application of LQG on cosmology...
Black holes are the current puzzles in modern cosmology. Devoid of concrete knowledge beyond event horizon make them rigid enough not to be soaked by many languages and approaches. However our imagination is inclined towards them to a large extent. Dark energy being an accepted reason for the accelerating universe can be an active factor of most of the phenomenon in the cosmic history. We here...
Non-commutative geometry as a possible paradigm to understand quantum gravity is gaining more attention in last decades. Non-commutativity of the space-time breaks the Lorentz invariance and one uses Hopf algebra structure to regain consistent particle interpretation. It is thus of importance to study the status of equivalence principle in the non-commutative space- time.
We examine how the...
In this article, we attempt to explore the dark sector of the universe i.e. dark matter and dark energy, where the dark energy components are related to the modified $f(Q)$ Lagrangian, particularly a power law function $f(Q) = γ(\frac{Q}{Q_0})^n$, while the dark matter component is described by the Extended Bose-Einstein Condensate (EBEC) equation of state for dark matter, specifically, $p =...
Gravitational wave memory is a persistent non-oscillatory shift in the gravitational wave amplitude. Such effects are ubiquitous in astrophysical and cosmological cataclysmic events involving gravitational radiation. In this talk, we turn our attention to the case of a supernova neutrino burst generating the gravitational radiation. Previous studies along this line have demonstrated that a...
