Conveners
Parallel - ASP & GW: Session 1
- Mohamed Rameez
Parallel - ASP & GW: Session 2
- Prayush Kumar
Recently, Pulsar Timing Array (PTA) collaborations around the world have found evidence for a stochastic gravitational waves (GWs) background at the nanohertz frequencies. One of the possible sources for these low-frequency GWs are the supermassive black hole binaries (SMBHBs). Despite having several hundreds of SMBHB candidates, none of them are confirmed till date. In 2022, Ning Jiang et....
Pulsar timing array experiments (PTAs) aim to detect ultra-low-frequency (∼1–100 nHz) gravitational waves (GWs) by monitoring an ensemble of millisecond pulsars (MSPs) distributed across the Galaxy. The intrinsic wander of the rotation rate of the constituent pulsars, variations in dispersion measure (DM), scatter-broadening, and instrumental noise of radio telescopes often correlate with the...
A minimally extended version of the Standard Model where baryon number is promoted as a gauged $U(1)_B$ symmetry can be made anomaly-free by adding a set of vector-like fermions. Such a scenario can evade the spin-dependent direct detection bounds on vector-like fermions. Additionally, the lightest component of the exotic fermion sector behaves as a viable dark matter candidate. We show that...
The existence of an early matter-dominated epoch prior to the big bang nucleosynthesis (BBN) may lead to a scenario where thermal dark matter cools faster than the plasma before the onset of reheating. This extra cooling reduces the free-streaming horizon of the dark matter compared to the usual radiation-dominated cosmology. Enhanced matter perturbations for scales entering the horizon before...
The exact sources of high-energy neutrinos detected by the IceCube neutrino observatory still remain a mystery. For the first time, this work explores the hypothesis that galaxy mergers may serve as sources for these high-energy neutrinos. Galaxy mergers can host very high-energy hadronic and photohadronic processes, which may produce very high-energy neutrinos. We perform an unbinned...
The search for magnetic monopoles has intrigued physicists for centuries. The NOvA Far Detector (FD), primarily used for studying neutrino oscillations, possesses a unique potential to search for exotic subluminal particles such as magnetic monopoles. With its extensive surface area of over 4,000 m², its location near the earth's surface, and minimal overburden, the 14 kt FD is highly...
Galaxy clusters could produce gamma rays from inverse Compton scattering of cosmic ray electrons or hadronic interactions of cosmic ray protons with the intracluster medium. It is still an open question on whether gamma-ray emission (> GeV energies) has been detected from galaxy clusters. We carry out a systematic search for gamma-ray emission based on 300 galaxy clusters selected from the...
We show that observations of primordial gravitational waves of inflationary origin can shed light into the scale of flavor violation in a flavon model which also explains the mass hierarchy of fermions. The energy density stored in oscillations of the flavon field around the minimum of its potential redshifts as matter and is expected to dominate over radiation in the early universe. At the...
Galactic Dark Matter (DM) particles can get captured inside celestial bodies if they have some non-zero but weak interaction with the nucleons. Due to their significant size and lifetime, these celestial bodies can capture huge amounts of DM particles, and eventually, an overly dense dark core is created. This core can further collapse and form a minuscule Balck Hole (BH) that can eat up the...
We discuss the stochastic gravitational wave background emitted from a network of 'quasi-stable' strings (QSS) and its realization in grand unified theories. A symmetry breaking in the early universe produces monopoles that suffer partial inflation. A subsequent symmetry breaking at a lower energy scale creates cosmic strings that are effectively stable against the breaking via Schwinger...
The Gravitational Wave (GW) interferometers LISA and ET are expected to be functional in the next decade(s). In this talk, I shall discuss about possible synergies between these two detectors, with the aim of a multi-band detection of a cosmological stochastic GW background. I shall illustrate that LISA and ET operating together will have the opportunity to effectively assess the...
We study thermal and non-thermal resonant leptogenesis in a general setting where a heavy scalar $\phi$ decays to right-handed neutrinos (RHNs) whose further out-of-equilibrium decay generates the required lepton asymmetry. Domination of the energy budget of the Universe by the $\phi$ or the RHNs alters the evolution history of the primordial gravitational waves (PGW), of inflationary origin,...
Primordial black holes with magnetic charges may evade constraints from Hawking radiation, leading to their significant population even for masses below $10^{15} \text{g}$, a range previously considered improbable. They could, therefore, potentially contribute to a component of dark matter in the universe.
This talk will focus on establishing Parker-type bounds on the population...
Chameleon dark energy models are a popular alternative to the standard cosmological constant model. These models consist of a new light degree of freedom, called chameleon, with a density dependent mass and a non-trivial coupling to both matter and photons. Owing to these couplings, chameleons can be produced inside the sun. However due to their density dependent mass, the chameleons produced...
