Iron K$\alpha$ line of Proca stars

Abstract

X-ray reflection spectroscopy can be a powerful tool to test the nature of astrophysical black holes. Extending previous work on Kerr black holes with scalar hair [1] and on boson stars [2], here we study whether astrophysical black hole candidates may be horizonless, self-gravitating, vector Bose-Einstein condensates, known as Proca stars [3]. We find that observations with current X-ray missions can only provide weak constraints and rule out solely Proca stars with low compactness. There are two reasons. First, at the moment we do not know the geometry of the corona, and therefore the uncertainty in the emissivity profile limits the ability to constrain the background metric. Second, the photon number count is low even in the case of a bright black hole binary, and we cannot have a precise measurement of the spectrum.

6 pages, 3 figures

References in corpus (9)

• Constraining Black Hole Spin Via X-ray Spectroscopy
• A code to compute the emission of thin accretion disks in non-Kerr space-times and test the nature of black hole candidates
• A new spin on black hole hair
• Iron K$\alpha$ line of Kerr black holes with scalar hair
• Testing the Kerr metric with the iron line and the KRZ parametrization
• Iron K$\alpha$ line of boson stars
• Constraining Black Holes with Light Boson Hair and Boson Stars using Epicyclic Frequencies and QPOs
• Construction and physical properties of Kerr black holes with scalar hair
• Constraining the Kerr parameters via X-ray reflection spectroscopy

Cited by in corpus (11)

• The imitation game: Proca stars that can mimic the Schwarzschild shadow
• On the dynamical bar-mode instability in spinning bosonic stars
• Excited Kerr black holes with scalar hair
• Rotating Axion Boson Stars
• Equatorial timelike circular orbits around generic ultracompact objects
• Constructing spherically symmetric Einstein-Dirac systems with multiple spinors: Ansatz, wormholes and other analytical solutions
• RELXILL_NK: a relativistic reflection model for testing Einstein's gravity
• Fixing the dynamical evolution of self-interacting vector fields
• Singularities in static spherically symmetric configurations of General Relativity with strongly nonlinear scalar fields
• Testing Gravity with Black Hole X-Ray Data
• Testing exterior spacetime of the neutron star via X-ray reflection spectroscopy