Accretion Process as a Probe of Extra Dimensions in MOG Compact Object Spacetimes

TL;DR

This paper explores how extra dimensions in modified gravity theories influence accretion processes around compact objects, revealing potential observational signatures that could be detectable with current telescopes.

Contribution

It provides analytical models of accretion onto higher-dimensional MOG compact objects, highlighting how extra dimensions affect ISCO, flux, and temperature.

Findings

Extra dimensions reduce the ISCO radius.

Accretion flux and temperature are enhanced by extra dimensions.

Predicted disk temperatures may be detectable with current observations.

Abstract

The idea of extra spatial dimensions arises from attempts to unify gravity with other fundamental interactions, develop a consistent theory of quantum gravity, and address open problems in particle physics and cosmology. Considerable attention has been devoted to understanding how such dimensions modify gravitational theories. One way to probe their impact is through the analytical study of astrophysical processes such as black hole accretion. Since accretion efficiently converts gravitational energy into radiation, this makes it a powerful tool to test modified gravity (MOG) theories and higher-dimensional frameworks via the behavior of dark compact objects like black holes, neutron stars, and white dwarfs. In this work, we investigate the dynamics of neutral particles around a higher-dimensional, regular, spherically symmetric MOG compact object, focusing on the innermost stable circular orbit (ISCO), energy flux, temperature, and differential luminosity. We further analyze the accretion of a perfect fluid onto the same object, deriving analytical expressions for the four-velocity and proper energy density of the inflowing matter. Our findings show that extra dimensions reduce the ISCO radius while enhancing the corresponding flux and temperature. Finally, by comparing the effective disk temperature $T_{\text{eff}}$ with Event Horizon Telescope (EHT) observations of Sgr A*, we argue that MOG and higher-dimensional corrections to the accretion disk properties could be close to the current threshold of detectability.