Talks

This session will be mostly practical. Within the framework of the 2-species LV model, we will use nullcline analysis to predict the outcome of competition in different situations. These include cases in which either or both competitors are subject to cooperative growth, which can lead to alternative stable states that emerge in (2-species) co-culture, but that are absent in any of the (1-species) monocultures.

We investigate the implications of memory burden on the gravitational wave (GW) spectrum arising from the Hawking evaporation of light primordial black holes (PBHs). By considering both rotating (Kerr) and non-rotating (Schwarzschild) PBHs, we demonstrate that the overproduction of primordial GWs from burdened PBHs could impose stringent constraints on the parameters governing backreaction effects. These constraints, derived from ∆Neff measurements by Planck and prospective experiments such as CMB-S4 and CMB-HD, offer novel insights into the impact of memory burden on PBH dynamics.

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 gravitational radiation. Previous studies along this line have demonstrated that a neutrino burst in such scenarios gives rise to a gravitational memory signal. Here, we specifically inquire about the alterations to the memory signal when neutrinos emitted from a supernova undergo self-interaction, presenting an avenue for indirectly detecting neutrino self-interaction.

In this talk, I will discuss a phenomenon called cosmic inflation in which the Universe went through accelerated exponential expansion to solve the horizon problem of Cosmological Microwave Background within a billionth of a trillionth of a trillionth of a second, in the very early Universe. This accelerated expansion, in its minimal form, is driven by a scalar field (inflaton) and it takes place when this scalar field slowly rolls down a potential well. However, the origin of this scalar field and the correct form of the scalar potential remains an open question in cosmology. I will present a string theory motivated model where the inflaton is connected to the geometry of the internal space -- the overall volume of it drives the inflation. In particular, I will present a construction where the overall volume modulus (scalar field) is dynamically stabilized to an exponentially large value only via perturbative corrections, also known as perturbative large volume scenario (LVS). In this framework, the robustness of the single-field inflationary model is checked against possible sub-leading corrections. In the later part of my talk, I will focus on the global embedding of the fibre inflation in perturbative LVS and show how our constructions pose less challenge in realizing a successful period of inflation.