Abstract Details
| Name: Anirban Dasgupta Affiliation: National Institute of Technology , Rourkela Conference ID: ASI2025_157 Title : Constraining Einstein-Maxwell-Dilaton-Axion Gravity from observed quasi periodic oscillations in black holes. Authors and Co-Authors : Anirban Dasgupta, Nishant Tiwari, Indrani Banerjee Abstract Type : Poster Abstract Category : High Energy Phenomena, Fundamental Physics and Astronomy Abstract : The general theory of relativity (GR) has fundamentally transformed our understanding of spacetime, offering a profound framework to describe gravitational interactions. Through its exceptional predictive power and mathematical elegance, GR has explained diverse phenomena, from planetary orbits to the bending of light by massive bodies. However, the theory encounters notable challenges, especially in addressing spacetime singularities—regions where physical laws cease to apply—and in accounting for the universe’s “dark sector,” which comprises dark matter and dark energy. Such limitations prompt the exploration of alternative theories of gravity. Among these, the string-inspired Einstein-Maxwell-dilaton-axion (EMDA) framework is particularly intriguing due to its pivotal role in both inflationary cosmology and the accelerated expansion of the current universe. In this study, we explore the charged, rotating Kerr-Sen black hole solution within the EMDA framework. Unlike the Kerr black holes predicted by GR, Kerr-Sen black holes possess a unique non-zero dilaton charge, introducing novel dynamics that could potentially align with observed astrophysical phenomena. To investigate this further, we utilize high-frequency quasi-periodic oscillations (HFPQOs) detected in five prominent black hole sources—GRO J1655-40, XTE J1550-564, GRS 1915+105, H 143+322, and Sgr A*. We evaluate eleven distinct HFPQO models, comparing their predictions for QPO frequencies with observational data to assess whether these black holes exhibit a non-vanishing dilaton charge. This approach allows us to place constraints on the dilaton charge for each model, potentially signaling deviations from GR. This investigation into the Kerr-Sen solution not only aids in exploring the EMDA theory’s relevance to astrophysics but also provides a promising avenue for addressing foundational issues in GR. Our findings have the potential to offer new perspectives on black hole physics and spacetime structure, contributing to the broader search for a more comprehensive theory of gravity. |