| Name: Vishwas Patel |
| Affiliation: Space Applications Centre, Indian Space Research Organisation |
| Conference ID: ASI2026_924 |
| Title: Simulating Relativistic Shadows for Blackhole and Naked singularity Spacetimes. |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Vishwas Patel(Space Applications Centre, Indian Space Research Organisation, Ahmedabad, India-380015), Pankaj S. Joshi(International Centre for Space and Cosmology, School of Arts and Sciences, Ahmedabad University, Ahmedabad-380009, India), Munn. V. Shukla(Space Applications Centre, Indian Space Research Organisation, Ahmedabad, India-380015) |
| Abstract: The recent shadow observations of Sgr A* by the Event Horizon Telescope are most effectively explained by the Joshi-Malafarina-Narayan type-1 (JMN-1) naked singularity and Schwarzschild black hole models, which are currently regarded as observationally degenerate spacetimes. The JMN-1 naked singularity results from the gravitational collapse of spherically symmetric matter with zero radial pressure. It casts a shadow for values of the parameter M0 > 2/3 , where it supports a photon sphere. The observationally verifiable differences between these two metrics are inadequately explored in the literature. Therefore, in our study, we conduct a detailed investigation of the possible differences in shadow images of the Schwarzschild black hole and the JMN-1 naked singularity under optically thin Bondi-Michel accretion using relativistic ray tracing. Using high-resolution image processing, we analyze shadow structures in both spatial and frequency domains through spectral analysis techniques, including 2-dimensional fast Fourier transform. Notably, the distinction between the simulated shadow images is more pronounced in the phase of the 2D Fourier transform than in the amplitude. Additionally, we apply error-based, perceptual, and information-theoretic image comparison metrics to quantify the differences in the spatial domain. The shadow image differences, derived from the developed Python framework, are rigorously validated through cross-comparison with independent, publicly available general relativistic radiative transfer codes. Furthermore, we find that the JMN-1 metric with M0 < 2/3 produces a ’full-moon’ image which closely resembles the intensity structure of the Little Red Dots (LRDs), which were recently observed with the JWST’s NIRCam instrument. The performed shadow simulations provide valuable insights that can help constrain the nature of ultra-compact objects at galactic centers using observations from the Event Horizon Telescope and future terahertz very long baseline interferometry (VLBI) networks.
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