10th International Conference on Gravitation and Cosmology: New Horizons and Singularities in Gravity (ICGC 2023)

Session

Plenary

6 Dec 2023, 10:00

IIT Guwahati

Conveners

Plenary

• Sayan Kar (Indian Institute of Technology Kharagpur)

Plenary

• Urjit Yajnik

Plenary

• Anjan ananda Sen (professor)

Plenary

• S Shankaranarayanan (Department of Physics, IIT Bombay)

Plenary

• Sukanta Bose (Washington State University)

Plenary

• Prayush Kumar (ICTS-TIFR)

Plenary

• Sarbari Guha (St. Xavier's College (Autonomous), Kolkata)

334. Binary Neutron Stars: from macroscopic collisions to microphysics

Luciano Rezzolla

06/12/2023, 10:00

I will argue that if black holes represent one the most fascinating implications of Einstein’s theory of gravity, neutron stars in binary system are its richest laboratory, where gravity blends with astrophysics and particle physics. I will discuss the rapid recent progress made in modelling these systems and show how the gravitational signal can provide tight constraints on the equation of...

335. Free-falling in Quantum Spacetime

Maulik Parikh

06/12/2023, 11:15

Gravity is usually regarded classically, obeying Newton's law or Einstein's equations. Here I will show that, when the gravitational field is treated quantum-mechanically, the classical trajectories of freely falling objects are subject to random fluctuations, or "noise". Intuitively, the fluctuations can be viewed as arising due to the bombardment of the falling object by gravitons. This...

336. LIGO observations and future with LIGO India

Surabhi Sachdev

06/12/2023, 12:00

We are in the era of gravitational-wave and multi-messenger astronomy. The latest catalog of transient events from LIGO-Virgo-KAGRA contains 90 high-confidence detections from the first three observing runs. The ongoing fourth observing run is yielding a steady stream of events, with public alerts being issued at a rate of approximately 2-3 per week. All observations are believed to originate...

343. Ultra-long wavelength gravitational waves with pulsar timing array

Bhal Chandra Joshi (National Centre for Radio Astrophysics, Pune / Indian Institute of Technology, Roorkee India)

07/12/2023, 09:30

A rapidly emerging messenger in astrophysics is gravitational waves (GWs). A new window in the GW spectrum was recently opened when emerging evidence for ultra-long wavelength or nanoHertz frequency GWs was reported by four major pulsar timing array experiments (PTAs). These experiments use a collection of widely separated pulsars in the sky to look for a characteristic spectrum and spatial...

344. Theoretical developments in modeling cosmological structure formation

Aseem Paranjape

07/12/2023, 10:15

The evolution and growth of the skeleton of the Cosmic Web goes hand-in-hand with the evolution of gas and galaxies in the Universe and intertwines primordial physics (the details of inflation, dark matter and dark energy) with astrophysics (reionization, star formation and the growth of black holes). Untangling this correlated evolution in order to use the Cosmic Web as a cosmological probe...

345. Gravitational Wave Detectors (India): Present status & future plans

Sendhil Raja

07/12/2023, 11:30

Gravitational Waves are the periodic stretching and contracting of space-time produced by rotating astrophysical objects possessing a finite quadrupole moment such as binary stars, binary neutron stars, neutron star-black hole binary or black-hole-black-hole binary, etc. A passing gravitational wave will modulate the distance between two inertial test masses albeit by a very miniscule amount....

346. Hunting for gravitational waves in the era of cosmic dawn

Pratika Dayal

07/12/2023, 12:15

Over the past decades, observations have established a sample of more than 200 bright Active galactic nuclei (AGN), powered by accretion onto massive black holes, in the first billion years of the Universe. The James Webb Space Telescope has significantly revised this sample by yielding a sample of unexpectedly numerous and large black holes (up to a 100 million solar masses) within the first...

349. Gravitational Wave Paleontology: a new frontier to probe massive stars through cosmic history

Floor Broekgaarden (Simons Foundation | Columbia | Johns Hopkins)

08/12/2023, 09:30

In this talk I will discuss the challenges and prospects of Gravitational-wave Paleontology: studying massive stars from their `remnants’ as compact object coalescences, with the goal to answer the key questions in gravitational-wave astronomy today: What can we learn from these gravitational-wave sources about the formation, lives, and explosive deaths of massive stars across cosmic time?...

352. Black hole thermodynamics in higher derivative theories of gravity

08/12/2023, 11:45

Einstein’s equations are a set of classical differential equations for gravity with maximum two space-time derivatives. Black holes are some singular solutions to Einstein’s equations. They behave like large thermodynamic objects, indicating that they are actually an ensemble of the quantum states of gravity. Now any consistent quantum completion of Einstein’s theory typically generates...

354. Do the Fundamental Constants change with Time?

Nissim Kanekar (National Centre for Radio Astrophysics, India)

09/12/2023, 09:30

Temporal evolution in low-energy fundamental constants such as the fine structure constant and the proton-electron mass ratio is a generic prediction of theories that attempt to unify the Standard Model of particle physics and general relativity. The exciting possibility of low-energy tests of such unification theories has inspired a number of methods to probe fundamental constant evolution on...

355. Cosmography with gravitational waves: from current detections to future observatories

Archisman Ghosh (Ghent University)

09/12/2023, 10:15

Compact binaries observed in gravitational waves (GWs) are standard distance indicators or standard sirens. This has opened up a novel path to measuring cosmological parameters such as the Hubble constant. In this talk we give a brief overview of the current results in this context from the LIGO-Virgo-KAGRA detector network, some of the near-future prospects, and finally move over to the...