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

6 Dec 2023, 09:30 → 9 Dec 2023, 21:30 Asia/Kolkata

IIT Guwahati

Santabrata Das (Indian Institute of Technology Guwahati)

The 10th International Conference on Gravitation and Cosmology (ICGC) will be hosted by the Indian Institute of Technology (IIT) Guwahati, India during December 6 - 9, 2023. Since its inception in 1987, ICGC meetings are held once in four years and are organized by the Indian Association for General Relativity and Gravitation (IAGRG). The tenth edition of this conference at IIT Guwahati aims to bring together experts working in the area of Gravitation and Cosmology to discuss the recent developments, present status and exchange ideas while providing young researchers from India an opportunity for interaction with experts. The programme will have a series of plenary lectures, with parallel and poster sessions.

In addition, this year, we are celebrating the birth-centenary year of Prof. Amal Kumar Raychaudhuri, a renowned relativist well-known for the Raychaudhuri equation. One special evening session will be organized in this meeting.

Another evening session will be organized to remember Prof. Thanu Padmanabhan and his invaluable contributions to gravitational physics.

Topics to be covered during the meeting: 

• Classical & Quantum Gravity
• Gravitational Waves
• Astrophysical Relativity
• Cosmology

Important Dates:

• Registration and abstract submission opens: August 1, 2023
• Abstract submission closes: September 15, 2023 (Extended till September 24, 2023)
• Request for registration fee waiver closes: September 15, 2023
• Decision on selected abstracts: Updated in indico on October 16, 2023
• Decision on registration fee waiver: Communicated on October 20, 2023
• Registration (and fee payment) closes: October 31, 2023
• Registration cancellation request closes: November 5, 2023

Organised by:          

                                               

CampusMap_IITG.pdf

ICGC-Group_Photo

Schedule_ICGC_Oral.pdf

Schedule_ICGC_Poster.pdf

Travel_Information.pdf

Wednesday 6 December

09:30 → 10:00 Inauguration

09:30 Inauguration

10:00 → 10:45 Plenary

Convener: Sayan Kar (Indian Institute of Technology Kharagpur)

10:00 Binary Neutron Stars: from macroscopic collisions to microphysics

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 state and sound speed for matter at nuclear densities, as well as on one of the most important consequences of general relativity for compact stars: the existence of a maximum mass. Finally, I will discuss how the merger may lead to a phase transition from hadronic to quark matter. Such a process would lead to a signature in the post-merger gravitational-wave signal and open an observational window on the production of quark matter in the present Universe.

Speaker: Luciano Rezzolla

10:45 → 11:15 Tea Break

11:15 → 12:45 Plenary

Convener: Urjit Yajnik

11:15 Free-falling in Quantum Spacetime

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 fundamental noise might even be observable at gravitational wave detectors and, if detected, would provide experimental evidence for the quantization of gravity. I will also show that, when these results are extended to congruences of geodesics, the quantum fluctuations of spacetime give rise to an additional term in the Raychaudhuri equation.

Speaker: Maulik Parikh

12:00 LIGO observations and future with LIGO India

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 from merging neutron stars and/ or black holes, and are providing new insights into the properties and origins of compact objects and binaries. In this talk, I will provide a summary of the key observations to date, highlighting what we can learn about the astrophysics of compact objects. I will also discuss what these observations mean for the future when LIGO India comes online, expanding the global detector network and ushering in an even brighter era of gravitational-wave astronomy.

Speaker: Surabhi Sachdev

12:45 → 14:15 Lunch Break

14:15 → 16:30 Workshop on Astrophysical Relativity

Conveners: Arunava Mukherjee (Saha Institute of Nuclear Physics (SINP), HBNI, Kolkata), Indranil Chattopadhyay (ARIES)

14:15 AstroSat - Indian Space-based Multi-wavelength Observatory (Invited Talk)

AstroSat, India's first multi-wavelength space observatory is an unique platform to observe cosmic X-ray sources, especially to probe the strong gravity of 'compact' objects. I will discuss the capabilities of AstroSat and present some interesting results to decipher the environment around the 'compact' objects.

Speaker: Anuj Nandi (Space Astronomy Group, ISITE Campus, U. R. Rao Satellite Centre)

14:45 Accreting Millisecond X-ray Pulsars: Probing Strong Field Gravity

Speaker: aru beri (IISER Mohali, India)

15:00 Misaligned circum-single disks embedded in an AGN disk

Speaker: Bhupendra Mishra (Nicolaus Copernicus Astronomical Center Warsaw Poland)

15:15 Mass loss from relativistic magnetized accretion disc around rotating black holes

Speaker: Camelia Jana

15:30 Investigating the existence of gravitomagnetic monopole in M87*

Speaker: Dr Chandrachur Chakraborty

15:45 Equation of states in the curved spacetime of compact stars and their effects on tidal deformability

Speaker: Golam Mortuza Hossain (IISER Kolkata)

16:00 Microlensing Black Hole Shadows

Speaker: HIMANSHU VERMA (IIT Bombay)

16:15 High-soft to low-hard state transition in black hole X-ray binaries with GRMHD simulations

Speaker: Indu Kalpa Dihingia

14:15 → 16:30 Workshop on Classical & Quantum Gravity

Conveners: KINJALK LOCHAN (IISER Mohali), Prof. Swapna Mahapatra (Utkal University)

14:15 Regular spacetimes: black holes, wormholes and bubbles (Invited talk)

In this talk, I will provide a brief overview of regular spacetimes in theories of gravity. In particular, I will primarily review some of the well--known regular black holes and also discuss wormholes and bubble spacetimes. Some recent results, as well as physical effects in such spacetimes will be mentioned. We will end with
general comments and open questions.

Speaker: Sayan Kar (Indian Institute of Technology Kharagpur)

14:45 Influence of gravity on the quantum speed limit in neutrino oscillations (Session 1)

Speaker: Abhishek Jha (Indian Institute of Science)

14:45 Pole-skipping in holography with scalar-Gauss-Bonnet coupling (Session 2)

Speaker: Banashree Baishya (IIT Guwahati)

15:00 New regular black holes: geometry, matter sources and shadow profiles (Session 1)

Speaker: Mr Anjan Kar (Indian Institute of Technology Kharagpur)

15:00 Singularity free Emergent Universe from Dynamical wormhole (Session 2)

Speaker: Bikash Chandra Paul (North Bengal University)

15:15 Gravitational radiation from binary systems in f (R) gravity: A semi-classical approach (Session 1)

Speaker: Ashish Narang (Institute of Physics, Bhubaneswar)

15:15 Thermodynamics of multi-horizon spacetimes (Session 2)

Speaker: Chiranjeeb Singha

15:30 Phases of scalar and fermionic field theories in thermal Anti-de Sitter Spaces (Session 1)

Speaker: Ms ASTHA KAKKAR (DEPARTMENT OF PHYSICS AND ASTROPHYSICS, UNIVERSITY OF DELHI, DELHI - 110007, INDIA)

15:30 The Conspiracy of dS Space in String Theory (?) (Session 2)

Speaker: Ms Dibya Chakraborty (Graduate students)

15:45 An analytical approach to compute conductivity of p-wave holographic superconductors (Session 2)

Speaker: Diganta Parai (University of Hyderabad, PDRF)

15:45 Effective quantum states for trapped surfaces (Session 1)

Speaker: Ayan Chatterjee (Central University of Himachal Pradesh)

16:00 Are multiple reflecting boundaries capable of enhancing entanglement harvesting? (Session 2)

Speaker: Dipankar Barman (Indian Institute of Technology Guwahati)

16:00 Particle dynamics and new horizon structure around Kerr-Newman singularity (Session 1)

Speaker: Mr Ayanendu Dutta (Jadavpur University)

16:15 Energetics of a self-gravitating quantum system of charged particles (Session 1)

Speaker: BALJEET KAUR LOTTE (Siksha 'O' Anusandhan Deemed to be University)

16:15 Unruh-de Witt detectors in curved spacetime (Session 2)

Speaker: Hari K (Indian Institute of Technology, Madras)

14:15 → 16:30 Workshop on Cosmology

Conveners: Girish Kulkarni (Tata Institute of Fundamental Research), Pravabati chingangbam

14:15 Mapping the baryonic Universe: a new window into the cosmos (Invited Talk)

Mapping the baryonic content of the Universe, especially after the epoch of Cosmic Dawn -- the birth of the first stars and galaxies --- promises rich insights into both astrophysics and cosmology. The technique of intensity mapping (IM) has emerged as a powerful tool to explore this phase of the Universe by measuring the integrated emission from sources over a broad range of frequencies. A particular advantage of IM is that it provides a tomographic, or three-dimensional picture of the Universe, unlocking significantly more information than we presently have from galaxy surveys. Astrophysical uncertainties, however, constitute an important systematic in our attempts to constrain cosmology with IM. I describe an innovative approach which allows us to fully utilize our current knowledge of astrophysics in order to develop cosmological forecasts from IM. Analytically driven extensions to this framework allow us to interpret the latest auto-correlation IM results from the MeerKAT facility, as well as its counterparts in the microwave and sub-millimetre regimes. The framework can be used to exploit synergies with other complementary surveys, thereby opening up the fascinating possibility of constraining physics beyond Lambda CDM from future IM observations.

Speaker: Hamsa Padmanabhan

14:45 Self-interactions of ULDM to the rescue? (Session 2)

Speaker: Bihag Dave (Ahmedabad University)

14:45 Using Big Bang Nucleosynthesis to constrain f(R) gravity scalarons and primordial black hole masses (Session 1)

Speaker: Mr ABHIJIT TALUKDAR (Gauhati University)

15:00 Exploring Cosmic Anisotropy in the Bianchi-I Cosmological Model (Session 1)

Speaker: ANSHUL Verma (Indian Institute of Technology - BHU)

15:00 Model-independent reconstruction of the evolution of dark energy using Gaussian process regression (Session 2)

Speaker: Bikash Ranjan Dinda

15:15 Detectable signatures of non-Bunch-Davies 3-point correlation from primordial magnetic fields: CMB μT spectrum (Session 1)

Speaker: Arko Bhaumik (Indian Statistical Institute, Kolkata)

15:15 Probing the signatures of astrophysical scatter in the EoR 21cm signal using auto-bispectrum (Session 2)

Speaker: Chandra Shekhar Murmu (Indian Institute of Technology Indore)

15:30 Effects of Z3 symmetric dark matter models on global 21-cm signal (Session 2)

Speaker: Debarun Paul (Indian Statistical Institute, Kolkata)

15:30 Extremely magnified stars in cluster lenses (Session 1)

Speaker: Ashish Kumar Meena (Ben-Gurion University of the Negev)

15:45 An effective field theory approach to understand the primordial magnetogenesis (Session 1)

Speaker: Mr Ashu Kushwaha

15:45 Dark energy, D-branes, and Pulsar Timing Arrays (Session 2)

Speaker: Ms Debika Chowdhury

16:00 Ruling out Strongly Interacting Dark Matter–Dark Radiation Models from Joint Observations of Cosmic Microwave Background and Quasar Absorption Spectra (Session 1)

Speaker: Dr Atrideb Chatterjee (Inter-University Centre for Astronomy and Astrophysics)

16:00 Statistical Approaches to Study statistical Isotropy in CMB Sky maps (Session 2)

Speaker: Dipanshu G (IISER Pune & RRI)

16:15 Expansion-collapse duality between Einstein and Jordan frames: Implications at quantum level (Session 2)

Speaker: Dipayan Mukherjee (Indian Institute of Science Education and Research Mohali)

16:15 Squeezing, Chaos and Thermalization in Periodically Driven Quantum Systems: The Case of Bosonic Preheating (Session 1)

Speaker: Ayan Chakraborty (INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI)

14:15 → 16:30 Workshop on Gravitational Waves

Conveners: Parameswaran Ajith (International Centre for Theoretical Sciences (ICTS)), Sukanta Bose (Washington State University)

14:15 Probing fundamental physics with gravitational wave observations (Invited Talk)

Speaker: Anuradha Gupta (The University of Mississippi)

14:45 Quasinormal Modes of Slowly Rotating Black Holes in Dynamical Chern-Simons Gravity up to Second Order in Spin

Speaker: Alapati Tharaka Rama Chowdary (Indian Institute of Technology, Bombay)

15:00 Noise analysis of the Indian Pulsar Timing Array data release I

Speaker: Aman Srivastava

15:15 Novel probes of dark matter with continuous gravitational waves

Speaker: Andrew Miller

15:30 Multi-band Extension of the Wideband Timing Technique

Speaker: Avinash Kumar Paladi (Indian Institute of Science)

15:45 Probing globular clusters and other astrophysical environments with gravitational waves emitted by accelerated compact binary mergers

Speaker: AVINASH TIWARI (IUCAA, PUNE)

16:00 A Bayesian investigation of the neutron star equation-of-state vs. gravity degeneracy

Speaker: Bhaskar Biswas (Universität Hamburg)

16:15 Analysing the sensitivity of nuclear equation of state parameters with stellar observables using f-modes oscillations in Neutron Stars

Speaker: Mr Debanjan Guha Roy (Birla Institute of Technology & Science Pilani, Hyderabad Campus, Secunderabad, Telangana, India)

16:30 → 17:00 Tea Break

17:00 → 18:00 Poster Session

18:00 → 19:30 Special Sessions: Prof. Padmanabhan's Memorial Session

Conveners: Prof.Jasjeet Singh Bagla, S Shankaranarayanan (Department of Physics, IIT Bombay)

18:00 Biographical overview

Speaker: Prof.Jasjeet Singh Bagla

18:30 Quantum Gravity (ħ=1)

Speaker: KINJALK LOCHAN (IISER Mohali)

19:00 Induced Gravity (ħ=1 to ħ=0)

Speaker: Sudipta Sarkar (IIT, Gandhinagar)

19:45 → 21:30 Dinner

Thursday 7 December

09:30 → 11:00 Plenary

Convener: Anjan ananda Sen (professor)

09:30 Ultra-long wavelength gravitational waves with pulsar timing array

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 correlation due to an isotropic stochastic gravitational wave background (SGWB) believed to originate by the superposition of continuous gravitational waves emitted by an ensemble of gravitational radiation dominated in-spiralling super-massive black hole binary systems. A review of these experiments in the context of SGWB will be presented in this talk followed by a discussion of results of joint analysis by Indo-Japanese pulsar timing array (InPTA) and European pulsar timing array (EPTA) collaboration. These results will be examined in the context of similar results from Parkes pulsar timing array (PPTA), North American nanoHertz Observatory for gravitational waves (NANOgrav) and Chinese pulsar timing array (CPTA). Results from a recent comparison of these results jointly by International pulsar timing array (IPTA) will be presented, which suggests a higher significance detection after combining data from all the experiments. Recent efforts in improving the noise models with low frequency data and challenges in IPTA data combination will be described. Finally, the talk concludes with a brief look at possible new astrophysics, where the PTA data as well as multi-messenger astronomy is likely to contribute significantly in developing the field of gravitation and cosmology.

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

10:15 Theoretical developments in modeling cosmological structure formation

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 requires a judicial use of theoretical techniques ranging from perturbation theory and non-linear analytical approximations to semi-numerical models to full-fledged numerical simulations of dark matter, gas and galaxies. Such techniques are critical in understanding the degeneracies between cosmology and astrophysics that are imprinted on any given astrophysical probe of cosmology. I will discuss some of the progress in this field over the last several years, highlighting a few different themes from the literature. At low redshifts, I will discuss the emerging importance of uncertain physical effects such as galaxy assembly bias and the role played by novel statistical probes of nonlinear structure. At high redshifts, I will briefly describe the development of accurate and fast tools for capturing the physics of reionization. Finally, I will showcase our recent efforts at distinguishing the `standard' Lambda-CDM model from alternative theories.

Speaker: Aseem Paranjape

11:00 → 11:30 Tea Break

11:30 → 13:00 Plenary

Convener: S Shankaranarayanan (Department of Physics, IIT Bombay)

11:30 Gravitational Wave Detectors (India): Present status & future plans

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. Gravitational waves can be detected by measuring these minuscule changes using techniques such as resonant bars, resonant spheres, interferometric measurement, etc. Of these the interferometer detector is most promising due to it broadband sensitivity and scalability in size. The Michelson interferometer is a 'natural' detector of gravitational waves because of the differential changes in its two orthogonal arms induced by the quadruple field of the gravitational waves. As the displacement of two mirrors separated by a distance L, scales with the distance interferometer detector with arm length of kms is required to be able to detect Gravitational waves. Two such km class detectors are the Laser Interferometer Gravitational-wave Observatory (LIGO) detectors in the US, located in Livingston, Louisiana, and Hanford, Washington, separated by about three thousand kilometers. The third detector labeled LIGO-India is being setup in India under a joint collaboration between NSF and DAE-DST. The talk will provide a brief overview of the LIGO-India Project, it’s current status and plans for it’s upgrades to “arrive” in the global network of Gravitational Wave Detectors with an optical configuration similar to the other two LIGO detectors. The various activities on the Indian side for the LIGO-India Project will be presented in detail. The activities and plans for contributing to the next generation Gravitational Wave detector and a possible deci-Hz Gravitational Wave detector in space will also be discussed briefly.

Speaker: Sendhil Raja

12:15 Hunting for gravitational waves in the era of cosmic dawn

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 600 million years, posing an enormous challenge for black hole and galaxy formation models. Starting with possible pathways for creating such heavy black holes in the early Universe, I will show a census of the black holes and their properties expected through cosmic time. I will use these to highlight the gravitational wave event rates expected to be detected by LISA (the Laser Interferometer Space Antenna). Straddling the fields of cosmology, galaxy formation and black hole physics, I will show how theoretical models that couple the evolution of dark matter halos, their baryonic components and their black holes are crucially required to make predictions for facilities such as LISA.

Speaker: Pratika Dayal

13:00 → 14:30 Lunch Break

14:30 → 16:00 Workshop on Astrophysical Relativity

Conveners: Arunava Mukherjee (Saha Institute of Nuclear Physics (SINP), HBNI, Kolkata), Indranil Chattopadhyay (ARIES)

14:30 Testing the equivalence principle with Blackhole image observations

Speaker: JOSEPH P J (IISER Mohali)

14:45 The light bending phenomenon for a pulsar-black hole binary

Speaker: Jyotijwal Debnath

15:00 Universe at extreme energies through GZK neutrinos and photons

Speaker: Mr Prantik Sarmah (Indian Institute of Technology Guwahati)

15:15 DEEP-TOV FOR CHARACTERIZING NEUTRON STARS

Speaker: praveer tiwari (Indian Institute of Technology, Bombay)

15:30 Superradiant driven evoulution of Active Galactic Nuclei

Speaker: Priyanka Sarmah (phd student)

15:45 Black hole mimickers in light of the recently observed shadows of Sagittarius A* and M87*

Speaker: Dr Rajibul Shaikh (Seoul National University of Science and Technology)

14:30 → 16:00 Workshop on Classical & Quantum Gravity

Conveners: KINJALK LOCHAN (IISER Mohali), Prof. Swapna Mahapatra (Utkal University)

14:30 End-state of gravitational collapse of scalar and vector fields: Strong naked singularities (Session 2)

Speaker: Koushiki Bhattacharyya (Ahmedabad University)

14:30 Spontaneous Symmetry Breaking in Rindler frame and AdS space (Session 1)

Speaker: Haridev S R

14:45 Analyzing quantum gravity spillover in the semiclassical regime (Session 1)

Speaker: Harkirat Singh Sahota (Indian Institute of Science Education and Research Mohali, India)

14:45 Boundary terms and Brown-York quasi-local parameters for scalar-tensor theory (Session 2)

Speaker: Krishnakanta Bhattacharya (Fukushima University)

15:00 A master equation for gravitational wave memory (Session 1)

Speaker: Indranil Chakraborty (Indian Institute of Technology Bombay)

15:00 Membrane paradigm for slowly spinning compact objects (Session 2)

Speaker: M. V. S. Saketh (Max Planck institute for gravitational physics, Potsdam (Albert Einstein Institute))

15:15 Charged Scalar Hair on Reissner-Nordström Black Holes (Session 2)

Speaker: Muhammed Shafeeque (Indian Institute of Technology Guwahati, India)

15:15 Unruh effect via radiative energy level shift (Session 1)

Speaker: Jaffino Stargen D

15:30 Fate of an infalling Passenger at the Cauchy Horizon of a Reissner-Nordström Black Hole (Session 2)

Speaker: Mr Nihar Ranjan Ghosh

15:30 QBHs in the Sky (Session 1)

Speaker: Kabir Chakravarti (CEICO, FZU, Prague)

15:45 Gravitational collapse with torsion and nonsingular Universe in a black hole (Session 2)

Speaker: Nikodem Poplawski

15:45 Rindler trajectories and Rindler horizons in the Schwarzschild spacetime (Session 1)

Speaker: Kajol Paithankar (Indian Institute of Astrophysics, Bengaluru, India)

14:30 → 16:00 Workshop on Cosmology

Conveners: Girish Kulkarni (Tata Institute of Fundamental Research), Pravabati chingangbam

14:30 Morphological Characterization of Galactic Foreground Emissions (Session 1)

Speaker: Fazlu Rahman

14:30 Probing the HI distribution during post-reionization using the redshifted 21-cm marked power spectrum (Session 2)

Speaker: Dr Mohammad Kamran (Uppsala University)

14:45 Cosmological events on the stochastic background of inflationary gravitational waves (Session 2)

Speaker: N Malsawmtluangi

14:45 Ultra-light primordial black holes from first-order phase transition with unique gravitational wave spectrum (Session 1)

Speaker: Indrajit Saha (IIT Guwahati, India)

15:00 Emergence of cosmic space with Barrow entropy, a non-equilibrium thermodynamic description (Session 2)

Speaker: NANDHIDA KRISHNAN P (Ph.d, Department of Physics, Cochin University of Science and Technology)

15:00 Measuring secondary halo bias using nearest neighbor distributions (Session 1)

Speaker: Kaustubh Gupta (Indian Institute of Science Education and Research Pune)

15:15 Galaxy-dark matter connection of photometric galaxies from the HSC-SSP Survey using weak lensing (Session 2)

Speaker: Navin Chaurasiya (IUCAA)

15:15 Impact of sources of Epoch of Reionization (EoR) on the 21-cm bispectrum (Session 1)

Speaker: Leon Noble (Indian Institute of Technology Indore)

15:30 The abundance of core--collapsed subhalos in SIDM: insights from structure formation in ΛCDM (Session 2)

Speaker: Neev Shah

15:30 The co-evolution of supermassive black holes and their host haloes (Session 1)

Speaker: Mahavir Sharma (IIT Bhilai)

15:45 Primordial black hole reheating and its possible signatures (Session 1)

Speaker: MD RIAJUL Haque (Indian Institute of Technology Madras)

15:45 Ultra-low mass primordial black holes in the early universe can explain the PTA signal (Session 2)

Speaker: Nilanjandev Bhaumik (Indian Institute of Science, Bengaluru)

14:30 → 16:00 Workshop on Gravitational Waves

Conveners: Parameswaran Ajith (International Centre for Theoretical Sciences (ICTS)), Sukanta Bose (Washington State University)

14:30 “ENIGMA” - An aligned-spin eccentric IMR waveform model for compact binary mergers

Speaker: Kaushik Paul (Indian Institute of Technology Madras)

14:45 Inferring the quantum black hole signatures from gravitational-wave observations

Speaker: Krishnendu N V

15:00 Testing general relativity via direct measurement of black hole kicks

Speaker: Parthapratim Mahapatra (Chennai Mathematical Institute)

15:15 Testing of general relativity at the fourth post-Newtonian order

Speaker: Dr Poulami Dutta Roy (Chennai Mathematical Institute)

15:30 Precision Gravity: Gravitational waves using Feynman diagrams

Speaker: Raj Patil (Max Planck Institute for Gravitational Physics (Albert Einstein Institute) and Humboldt University)

15:45 Addressing issues in defining the Love numbers for black holes

Speaker: Rajendra Prasad Bhatt (Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India.)

16:00 → 16:30 Tea Break

16:30 → 18:00 Special Sessions: Prof. A. K. Raychaudhuri Centenary Session

Convener: Narayan Banerjee (IISER Kolkata)

16:30 Raychaudhuri and the singularity theorems

Speaker: José M Senovilla (University of the Basque Country UPV/EHU)

18:00 → 19:30 Poster Session

19:45 → 21:30 Dinner

Friday 8 December

09:30 → 10:15 Plenary

Convener: Sukanta Bose (Washington State University)

09:30 Gravitational Wave Paleontology: a new frontier to probe massive stars through cosmic history

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? How do we unravel the gravitational-wave formation channels? I will discuss open challenges in gravitational waves including the “Uncertainty Challenge” and give an overview of current efforts in the field to overcome this.

Speaker: Floor Broekgaarden (Simons Foundation | Columbia | Johns Hopkins)

10:15 → 11:15 Special Sessions: Special Gender Session

Convener: Harvinder Kaur Jassal

10:15 Introducing Working Group on Gender

Speaker: Sumati Surya

10:30 Women of Gravity

Speaker: Bindu Bambah (University of Hyderabad)

11:15 → 11:45 Tea Break

11:45 → 12:30 Plenary

Convener: Dr Prayush Kumar (ICTS-TIFR)

11:45 Black hole thermodynamics in higher derivative theories of gravity

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 several higher derivative corrections. Therefore we expect that black holes will continue to satisfy the laws of thermodynamics even after adding the quantum gravity induced corrections to Einstein’s equation. In this talk, we would like to see to what extent we could prove this expectation.

12:45 → 14:15 Lunch Break

14:15 → 16:30 Workshop on Astrophysical Relativity

Conveners: Arunava Mukherjee (Saha Institute of Nuclear Physics (SINP), HBNI, Kolkata), Indranil Chattopadhyay (ARIES)

14:15 Astrophysical Implications of Gravitational Wave Observations (Invited Talk)

Since the Nobel winning discovery of gravitational waves (GWs) by the LIGO-Virgo-Kagra (LVK) detectors from merging compact object binaries, understanding the various astrophysical formation channels of these sources has come to sharp focus. While qualitatively, the processes involved in producing these astrophysical systems are well understood, cutting-edge research is underway to put better constraints on several uncertain aspects that can affect the distribution of properties and expected rate of mergers depending on the formation channel. I will give a brief overview of the various formation channels, their unique characteristics, and the major sources of uncertainties. I will give a broad overview of the current state-of-the art of our theoretical understanding and predictions and discuss possible ways forward, using GWs in different frequency bands with future and upgraded detectors, and using other ongoing and upcoming electromagnetic surveys that can provide the key ingredients to better model GW sources.

Speaker: Sourav Chatterjee (TIFR, Mumbai)

14:45 Probing the Accretion/Ejection Geometry of X-ray Binaries Using Spectro-Polarimetry Study

Speaker: Samir Mandal (Indian Institute of Space Science and Technology)

15:00 Oscillating shocks in the transonic, viscous, variable Γ accretion flows around black holes

Speaker: Sanjit Debnath (Aryabhatta Research Institute of Observational Sciences (ARIES), INDIA)

15:15 Imprints of spin on the solution and emission spectrum of accretion flows around black holes

Speaker: Shilpa Sarkar (Harish Chandra Research Institute (HRI))

15:30 Shadow of regular black hole in scalar-tensor-vector gravity theory

Speaker: subhadip sau (Jhargram Raj College)

15:45 Spectral energy distributions for transonic accretion flow in non-Kerr spacetime

Speaker: Mr Subhankar Patra

16:00 White dwarfs in Gaia survey to constrain the fine-structure constant

Speaker: Dr Surajit Kalita (University of Cape Town)

14:15 → 16:30 Workshop on Classical & Quantum Gravity

Conveners: KINJALK LOCHAN (IISER Mohali), Prof. Swapna Mahapatra (Utkal University)

14:15 Even a tiniest positive cosmological constant has a long tail (Invited Talk)

The physics of gravitational waves is well understood for asymptotically flat space-times. Asymptotic flatness presumes a vanishing cosmological constant. However, cosmological observations over the decades have indicated that our universe is undergoing an accelerated expansion, which is most simply modelled by a de Sitter universe or equivalently by a positive cosmological constant. Even a tiniest value of positive cosmological constant profoundly alters the asymptotic structure of space-times, forcing a re-look at the theory of gravitational radiation. We will present an overview of the study of gravitational radiation in the de Sitter universe. We will discuss the progress and state-of-the-art of the subject.

Speaker: Sk Jahanur Hoque (BITS Pilani, Hyderabad campus)

14:45 Causal description of marginally trapped regions in D dimensions (Session 2)

Speaker: Sashideep Gutti (bits pilani hyderabad campus)

14:45 The breaking point of general relativity through f(R) scalaron gravity and higher dimensional Kaluza-Klein gravity near Sgr A* (Session 1)

Speaker: P.C Lalremruati (Center of Excellence in Space Science India(CESSI), Indian Institute of Science Education and Research(IISER), Kolkata)

15:00 Gyroscopic Precession in the Vicinity of a Black Hole's Event Horizon and Naked Singularity for Static and Stationary Spacetime (Session 1)

Speaker: Paulami Majumder (IISER KOLKATA)

15:00 Stochastic aspects for cosmic fluids (Session 2)

Speaker: Seema Satin (Indian Institute of Science Education and Research Kolkata)

15:15 Harmonic coordinates in binary black hole mergers (Session 1)

Speaker: Dr Prayush Kumar (ICTS-TIFR)

15:15 Is the no-hair theorem a feature of gravity or General Relativity? (Session 2)

Speaker: Mr Semin Xavier

15:30 Compactified Hyperboloidal Evolution in Numerical Relativity (Session 2)

Speaker: Dr Shalabh Gautam

15:30 Maximal volume of a black hole in 2+1 dimensions (Session 1)

Speaker: Rahul Nigam

15:45 Cosmology of Bianchi type-I metric using renormalization group approach for quantum gravity (Session 1)

Speaker: Rituparna Mandal (University of Hyderabad)

15:45 Galactic wormholes: Geometry, stability, and echoes (Session 2)

Speaker: Shauvik Biswas (Indian Association for the Cultivation of Science, Kolkata-700032, India.)

16:00 Extra dimension(s) of vanishing proper length: A non-Einsteinian phase in gravity and the implications (Session 1)

Speaker: sandipan sengupta (IIT Kharagpur, India)

16:00 Raychaudhuri Equation in the Context of a Collapsing Fermionic Distribution Incorporating Effective Four-Fermi Interaction (Session 2)

Speaker: Shibendu Gupta Choudhury (S. N. Bose National Centre for Basic Sciences)

16:15 Dyonic Kerr-Sen black holes revisited: shadow profiles and consequences (Session 2)

Speaker: Dr Soumya Jana (Sitananda College)

14:15 → 16:30 Workshop on Cosmology

Conveners: Girish Kulkarni (Tata Institute of Fundamental Research), Pravabati chingangbam

14:15 Instrumentation for redshifted 21-cm line observations (Invited Talk)

Universe has several poorly constrained periods over its evolution. Formation of first stars and galaxies, followed by reionization of the intergalactic medium is one such epoch. Often referred to as "cosmic dawn", observing this period is extremely challenging due to the faint nature of the signals originating from it. The redshifted 21-cm line from neutral hydrogen offers one such possibility to observe the cosmic dawn and extract information about the nature of first stars and galaxies. In this talk, I will discuss our attempts at detecting the 21-cm signal from cosmic dawn. I will elaborate the challenges involved in detecting faint cosmological signals, and how our in-house designed experiments address those challenges. I will finally discuss the recent results from our observations, and explore how 21-cm signal can also be employed to probe other epochs at different redshifts.

Speaker: Saurabh Singh

14:45 Gravitational Waves Background from Quintessential Inflation and NANOGrav data (Session 1)

Speaker: Mr NUR JAMAN (Centre for Theoretical Physics, Jamia Millia Islamia)

14:45 The origin of supermassive black holes at high redshift (Session 2)

Speaker: Ritik Sharma

15:00 Consistency of loop quantum cosmology with the cosmic microwave background bispectrum (Session 2)

Speaker: Roshna K (National Institute of Technology Karnataka, Surathkal)

15:00 Reconstructing the universe with machine learning (Session 1)

Speaker: Purba Mukherjee (Indian Statistical Institute, Kolkata)

15:15 Loop-level contributions of primordial non-Gaussianities and their observational consequences (Session 1)

Speaker: Ragavendra H V

15:15 Qualitative Stability Analysis of Cosmological models in $f(T,\phi)$ Gravity (Session 2)

Speaker: S SS

15:30 A Bayesian Neural Network based ILC method to estimate accurate CMB polarization power spectrum over large angular scales (Session 2)

Speaker: Sarvesh Kumar Yadav (Raman Research Institute, Banglore, India)

15:30 A geometrical interpretation of foreground filters for HI intensity (Session 1)

Speaker: Dr Rahul Kothari (Indian Institute of Technology, Mandi)

15:45 HI stacking predictions for upcoming surveys with SKA precursors (Session 2)

Speaker: Sauraj Bharti (IISER Mohali, Punjab 140306, India)

15:45 Precision Weak Lensing Analysis In CMB Observations For Upcoming Missions (Session 1)

Speaker: Rajorshi Chandra (Raman Research Institute)

16:00 Cosmology from Cross-Correlation of ACT-DR4 CMB Lensing and DES-Y3 Cosmic Shear (Session 2)

Speaker: Shabbir Shaikh (Arizona State University)

16:00 Distinguishing cosmological models through quantum signatures of primordial perturbations (Session 1)

Speaker: Rathul nath Raveendran (Indian Association for the Cultivation of Science, Kolkata, India)

14:15 → 16:30 Workshop on Gravitational Waves

Conveners: Parameswaran Ajith (International Centre for Theoretical Sciences (ICTS)), Sukanta Bose (Washington State University)

14:15 New black hole mergers in LVK data from a gravitational wave search including higher-order harmonics (Invited Talk)

Nearly all of the previous gravitational wave (GW) searches in the LIGO-Virgo-Kagra (LVK) data include GW waveforms with only the dominant quadrupole mode, i.e., omitting higher-order harmonics such as the octupole which are predicted by general relativity. We improved our search pipeline by introducing higher harmonics in the GW templates, and downweighting noise transients (“glitches”) to improve the search sensitivity to high-mass binary black hole (BBH) mergers. We searched over the public LVK data from the third observing run (O3) and used the detection threshold as the astrophysical probability being over 0.5 (following the approach of the LVK catalogs). This led to the detection of 13 new BBH merger events. Some of the new events have interesting astrophysical properties such as populating the pair instability mass gap in the black hole (BH) mass distribution and high redshift. While our new events individually have modest false alarm rates (>~ 1/yr), combining all the 13 events with their respective pastro values could have an impact on population analysis studies (e.g., probing the evolution of mass and spin distribution of BHs with redshift).

Speaker: Tejaswi Venumadhav (UCSB)

14:45 Exploring the Efficacy of Curriculum Learning in Training Neural Networks for Gravitational Wave Detection and Parameter Estimation in Near-Realistic Conditions

Speaker: Rakesh Kabir

15:00 Black holes immersed in environment

Speaker: Sayak Datta (Max Planck Institute for Gravitational Physics (AEI))

15:15 Unmasking noise transients mimicking intermediate-mass black hole binaries

Speaker: Sayantan Ghosh (Indian Institute of Technology Bombay)

15:30 Effect of spins on the orbital dynamics of a binary system

Speaker: Soham Bhattacharyya (IIT Madras)

15:45 Gear-up for the Action Replay: Leveraging Lensing for Enhanced Gravitational-Wave Early-Warning

Speaker: Sourabh Magare (Inter University Center for Astronomy and Astrophysics)

16:00 Probing the nature of dark matter using gravitational-wave strong lensing

Speaker: Souvik jana (International Centre for Theoretical Sciences (ICTS))

16:30 → 17:00 Tea Break

17:00 → 18:15 Public Lecture

Convener: Sumati Surya

17:00 The Gravitational-Wave Revolution: Observing Some Of The Most Cataclysmic Events In The Universe With The Most Precise Detectors Ever Constructed

Speaker: David Reitze (California Institute of Technology)

18:15 → 19:30 Poster Session

19:45 → 21:30 Dinner

Saturday 9 December

09:30 → 11:00 Plenary

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

09:30 Do the Fundamental Constants change with Time?

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 a range of timescales, from years to billions of years. Astrophysical studies of redshifted spectral lines provide a powerful probe of such putative changes in the low-energy fundamental constants across a large fraction of the age of the Universe. After reviewing the current state of the field, I will describe new high-sensitivity results on changes in the proton-electron mass ratio over the last 8 Gyr using methanol radio spectral transitions. Finally, if time permits, I will discuss present limitations of such studies and the improvements that are likely to be possible with the advent of new experimental and observational facilities over the next decade.

Speaker: Nissim Kanekar (National Centre for Radio Astrophysics, India)

10:15 Cosmography with gravitational waves: from current detections to future observatories

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 unique opportunities offered by future GW observatories.

Speaker: Archisman Ghosh (Ghent University)

11:00 → 11:30 Tea Break

11:30 → 12:45 Poster Session

13:00 → 14:30 Lunch Break

14:30 → 17:00 Workshop on Astrophysical Relativity

Conveners: Arunava Mukherjee (Saha Institute of Nuclear Physics (SINP), HBNI, Kolkata), Indranil Chattopadhyay (ARIES)

14:30 Seeing Hot and Energetic Universe through X-ray Eyes (Invited Talk)

X-rays are the signatures of the high-energy Universe. The X-ray band probes extreme environments in the Universe, such as those near black holes or the surface of neutron stars. Observations in X-ray energies of the sky provides the opportunity to study such exotic objects in the Universe, allowing the exploration of physical processes in extreme conditions. Many space missions and instruments were realized since 1960s that contributed to the present understanding of the physics of various astronomical sources. A steady progress in technological development has put X-ray astronomy in the mainstay of astronomy and astrophysics. In this talk, I will provide an overview of the observational X-ray astronomy as well as current and future X-ray missions that have provided some path breaking scietific results to shed new lights on the nature of various astronomical sources as well as the physical mechanisms by which the X-rays are emitted. I will also briefly mention about India's first X-ray polarimetry instrument POLIX onboard XpoSat satellite that will soon be launched.

Speaker: Vikram Rana

15:00 Inclination distributions in tidal disruption events by spinning supermassive black holes

Speaker: Tamanjyot Singh (The University of Texas at Dallas)

15:15 Massive, magnetized compact stars: Theory and Simulation

Speaker: Zenia Zuraiq (Indian Institute of Science)

15:30 Gravitational analog of Gertsenshtein-Zeldovich effect.

Speaker: Susmita Jana

15:45 Astrophysical significance of tidal interaction between white dwarfs and intermediate-mass black holes

Speaker: Pritam Banerjee (Indian Institute of Technology Kharagpur)

16:00 Spectral and timing properties of GX 17+2 using AstroSat and NICER simultaneous view

Speaker: Dr Biplob Sarkar (Department of Applied Sciences, School of Engineering, Tezpur University)

16:15 Impact of the net vertical magnetic field on thick accreting torus around black holes

Speaker: SAMIK MITRA (Indian Institute of Technology Guwahati)

16:30 Investigation of black holes in analogous and astrophysical regimes

Speaker: Mayank Pathak

16:45 A deeper insight into the accretion scenario of BH-ULXs with XMM-Newton

Speaker: Mr Seshadri Majumder (Indian Institute of Technology, Guwahati)

14:30 → 17:00 Workshop on Classical & Quantum Gravity

Conveners: KINJALK LOCHAN (IISER Mohali), Prof. Swapna Mahapatra (Utkal University)

14:30 TBD (Invited Talk)

Speaker: Loganayagam R. (ICTS-TIFR, Bengaluru)

15:00 Gravitational wave memory for various black hole and wormhole geometries (Session 1)

Speaker: Soumya Bhattacharya (S.N.Bose National Center for Basic Sciences)

15:00 Some classical aspects of Ellis-Bronnikov wormholes embedded in a warped background. (Session 2)

Speaker: Suman Ghosh

15:15 Analytic three-dimensional hairy charged black holes and thermodynamics (Session 2)

Speaker: supragyan priyadarshinee

15:15 Quantum-to-classical transition of leading-order background fluctuations (Session 1)

Speaker: Sree Mahesh Chandran (Indian Institute of Technology Bombay)

15:30 An Effective Theory model for Black Hole Membranes from Constraints of Symmetry (Session 2)

Speaker: Swastik Bhattacharya (BITS Pilani Hyderabad)

15:30 Love for an Expanding universe and SdS black holes (Session 1)

Speaker: Sreejith Nair

15:45 A detection mechanism for black hole memory effect (Session 1)

Speaker: Srijit Bhattacharjee

15:45 Unified Insights in Gravity Theories: Asymptotic Symmetries and Celestial Holography (Session 2)

Speaker: Ms Tabasum Rahnuma (Indian Institute of Science Education and Research, Bhopal)

16:00 Particle creation in a dynamical gravitational wave background (Session 2)

Speaker: Tanmoy Chakraborty (Indian Association for the Cultivation of Science)

16:00 Radiative processes of single and entangled detectors on circular trajectories in (2+1) dimensional Minkowski spacetime (Session 1)

Speaker: Subhajit Barman (IIT Madras)

16:15 High-energy corrections to CGHS model: a systematic procedure (Session 2)

Speaker: Tausif Parvez (Indian Institute Of Technology Bombay)

16:15 Perturbing the perturbed: Quasi-normal mode instability in asymptotically de Sitter black holes (Session 1)

Speaker: Subhodeep Sarkar (Indian Institute of Information Technology, Allahabad; Centre for Theoretical Physics, Jamia Millia Islamia)

16:30 Emergent Spin in Quantum Cosmology of Bianchi Type-I Universe (Session 2)

Speaker: vishal kumar (Indian Institute of Technology Guwahati)

16:30 On the propagation of gravitational waves in matter-filled Bianchi I universe (Session 1)

Speaker: Sucheta Datta (St.Xavier's College (Autonomous), Kolkata, India)

14:30 → 17:00 Workshop on Cosmology

Conveners: Girish Kulkarni (Tata Institute of Fundamental Research), Pravabati chingangbam

14:30 The dynamics of Dark matter and the halo from Cluster to Dwarf scales (Invited Talk)

Speaker: Susmita Adhikari (IISER, Pune)

15:00 Loop contributions to the scalar power spectrum due to quartic order action in ultra slow roll inflation (Session 2)

Speaker: Mr SUVASHIS MAITY (INDIAN INSTITUTE OF TECHNOLOGY MADRAS)

15:00 Non-linear joint density-velocity evolution in f(R) theories of modified gravity (Session 1)

Speaker: Sharvari Nadkarni-Ghosh (IIT Kanpur)

15:15 A Local Perspective on Hubble Tension from Cosmological N-body Simulations (Session 2)

Speaker: Swati Gavas (Indian Institute of Science Education and Research Mohali (IISER-M))

15:15 Dynamical system analysis in teleparallel gravity with boundary term (Session 1)

Speaker: Mr Siddheshwar Kadam (BITS-Pilani Hyderabad Campus India)

15:30 Signature flip in deceleration parameter: A thermodynamic phase transition? (Session 2)

Speaker: Tanima Duary (INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH KOLKATA)

15:30 Synchrotron radiation from cosmic string wakes. (Session 1)

Speaker: Soumen Nayak

15:45 A semi-analytical treatment of coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds (Session 1)

Speaker: Sourav Pal (Indian Statistical Institute, Kolkata)

15:45 Non-linear regression with errors on both axes and its implications on Hubble tension (Session 2)

Speaker: Ujjwal Upadhyay

16:00 A new method to simultaneously determine the reionization history and power spectrum (Session 1)

Speaker: Suman Pramanick

16:00 Dark energy in light of the early JWST observations (Session 2)

Speaker: upala mukherjee

16:15 The possibility of Q-balls as cosmological and galactic dark matter (Session 1)

Speaker: Susobhan Mandal (IIT Bombay)

16:15 Towards a possible solution to the Hubble tension with Horndeski gravity (Session 2)

Speaker: Yashi Tiwari (Indian Institute of Science, Bangalore, India)

14:30 → 17:00 Workshop on Gravitational Waves

Conveners: Parameswaran Ajith (International Centre for Theoretical Sciences (ICTS)), Sukanta Bose (Washington State University)

14:30 TBD (Invited Talk)

Speaker: Nancy Aggarwal (Northwestern University)

15:00 Can LIGO Detect Non-Annihilating Dark Matter?

Speaker: Sulagna Bhattacharya (Tata Institute of Fundamental Research, Mumbai)

15:15 Tidal heating as a direct probe of Strange matter inside Neutron stars

Speaker: Suprovo Ghosh

15:30 A novel test of strong field gravity using binary black hole ringdowns

Speaker: Swetha Bhagwat (University of Birmingham)

15:45 Bayesian framework to infer the Hubble constant from cross-correlation of individual gravitational wave events with galaxies

Speaker: Mr Tathagata Ghosh (Inter-University Centre for Astronomy and Astrophysics)

16:00 Tidal deformation of dynamical horizons in binary black hole mergers and its imprint in their gravitational radiation

Speaker: Vaishak Prasad (International Centre for Theoretical Sciences - Tata Institute of Fundamental Research)

17:00 → 17:30 Tea Break

17:30 → 18:00 Conclusion: Concluding Remarks

19:45 → 21:30 Dinner