A simplified approach for reproducing fully relativistic spectra in X-ray binary systems: Application to Cygnus X-1

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Hauptverfasser: Papavasileiou, Th. V., Kosmas, O., Kosmas, T. S.
Format: Preprint
Veröffentlicht: 2024
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author Papavasileiou, Th. V.
Kosmas, O.
Kosmas, T. S.
author_facet Papavasileiou, Th. V.
Kosmas, O.
Kosmas, T. S.
contents General relativistic effects are strong near the black hole of an X-ray binary and significantly impact the total energy released at the innermost accretion disk's region. Our goal is to fully incorporate the black hole's spin and all the general relativistic effects on the observed spectra coming from X-ray binary systems while maintaining the simplicity of the standard disk model. That is possible by appropriately shifting only the disk's inner radius. We employ some of the most efficient pseudo-Newtonian potentials around Kerr black holes and derive two generalized disk temperature profiles, thus incorporating the spin's contribution to the thermal spectra. Then, we associate the observed radiative efficiency with the emission pattern featuring all the relativistic effects included in the kerrbb model, obtaining an expression about the modified inner radius of the disk. Moreover, we apply this method to Cygnus X-1 by fitting the observational data obtained during its high/soft and hard/low spectral states. The fully relativistic spectra are reproduced to a very good approximation with an error margin of 0.03-4%. The disk is parameterized by a modified innermost radius within the range of $(0.2-2)R_{ISCO}$, depending on the source's viewing angle and black hole spin. Relativistic effects near the black hole make an otherwise standard accretion disk with inclination $θ<60^{\circ}$ seem truncated to larger radii to a distant observer. On the other hand, an edge-on view of the disk gives the perspective of being pulled closer to the central object than the respective ISCO radius. In addition, we show that the observational data of Cygnus X-1 can be satisfactorily fitted by employing a reasonably simple lepto-hadronic jet model and a hybrid thermal/non-thermal corona along with the Kerr-adjusted standard accretion disk.
format Preprint
id arxiv_https___arxiv_org_abs_2408_02415
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A simplified approach for reproducing fully relativistic spectra in X-ray binary systems: Application to Cygnus X-1
Papavasileiou, Th. V.
Kosmas, O.
Kosmas, T. S.
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
General relativistic effects are strong near the black hole of an X-ray binary and significantly impact the total energy released at the innermost accretion disk's region. Our goal is to fully incorporate the black hole's spin and all the general relativistic effects on the observed spectra coming from X-ray binary systems while maintaining the simplicity of the standard disk model. That is possible by appropriately shifting only the disk's inner radius. We employ some of the most efficient pseudo-Newtonian potentials around Kerr black holes and derive two generalized disk temperature profiles, thus incorporating the spin's contribution to the thermal spectra. Then, we associate the observed radiative efficiency with the emission pattern featuring all the relativistic effects included in the kerrbb model, obtaining an expression about the modified inner radius of the disk. Moreover, we apply this method to Cygnus X-1 by fitting the observational data obtained during its high/soft and hard/low spectral states. The fully relativistic spectra are reproduced to a very good approximation with an error margin of 0.03-4%. The disk is parameterized by a modified innermost radius within the range of $(0.2-2)R_{ISCO}$, depending on the source's viewing angle and black hole spin. Relativistic effects near the black hole make an otherwise standard accretion disk with inclination $θ<60^{\circ}$ seem truncated to larger radii to a distant observer. On the other hand, an edge-on view of the disk gives the perspective of being pulled closer to the central object than the respective ISCO radius. In addition, we show that the observational data of Cygnus X-1 can be satisfactorily fitted by employing a reasonably simple lepto-hadronic jet model and a hybrid thermal/non-thermal corona along with the Kerr-adjusted standard accretion disk.
title A simplified approach for reproducing fully relativistic spectra in X-ray binary systems: Application to Cygnus X-1
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2408.02415