Absorption features caused by oscillations of electrons on the surface of a quark star

TL;DR

This paper explores how electron oscillations on quark star surfaces could produce observable absorption features in X-ray spectra, providing a potential method to detect and study quark stars through their vibrational modes.

Contribution

It derives the frequency spectrum of vortex hydrodynamical oscillations of electron seas on quark stars and links these oscillations to observable X-ray spectral features.

Findings

Hydro-cyclotron oscillations can explain absorption features at 0.7 keV and 1.4 keV in certain compact objects.

Vibrational modes could serve as observational signatures of quark stars.

The model offers a new way to verify the existence of quark stars through X-ray spectroscopy.

Abstract

If quark stars exist, they may be enveloped in thin electron layers (electron seas), which uniformly surround the entire star. These layers will be affected by the magnetic fields of quark stars in such a way that the electron seas would transmit hydromagnetic cyclotron waves, as studied in this paper. Particular attention is devoted to vortex hydrodynamical oscillations of the electron sea. The frequency spectrum of these oscillations is derived in analytic form. If the thermal X-ray spectra of quark stars are modulated by vortex hydrodynamical vibrations, the thermal spectra of compact stars, foremost central compact objects (CCOs) and X-ray dim isolated neutron stars (XDINSs), could be used to verify the existence of these vibrational modes observationally. The central compact object 1E 1207.4-5209 appears particularly interesting in this context, since its absorption features at 0.7 keV and 1.4 keV can be comfortably explained in the framework of the hydro-cyclotron oscillation model.