General Relativity and Compact Objects

TL;DR

This paper reviews key predictions of general relativity, such as black holes and gravitational waves, discusses quantum effects near horizons, and explores implications for compact objects like white dwarfs and black holes.

Contribution

It provides a conceptual overview of GR's predictions, examines quantum phenomena at horizons, and analyzes recent observations of white dwarfs and their impact on understanding compact object evolution.

Findings

Quantum particle production occurs at event horizons.

White dwarf systems with rapid spin challenge existing models.

Gravitational and electromagnetic radiation from compact objects have observable consequences.

Abstract

Starting with the conceptual foundation of general relativity (GR) - equivalence principle, space-time geometry and special relativity, I train cross hairs on two characteristic predictions of GR - black holes and gravitational waves. These two consequences of GR have played a significant role in relativistic astrophysics, e.g. compact X-ray sources, GRBs, quasars, blazars, coalescing binary pulsars, etc. With quantum theory wedded to GR, particle production from vacuum becomes a generic feature whenever event horizons are present. In this paper, I shall briefly discuss the fate of a `black hole atom' when Hawking radiation is taken into account. In the context of gravitational waves, I shall focus on the possible consequences of gravitational and electromagnetic radiation from highly magnetized and rapidly spinning white dwarfs. The discovery of RX J0648.0-4418 system - a WD in a binary with mass slightly over 1.2 $ M_{\odot}$, and rotating with spin period as short as 13.2 s, provides an impetus to revisit the problem of WD spin evolution due to energy loss.