General relativistic ray tracing around rotating black holes: exploring the SED parameter space for RIAF models.
Date
2024
Authors
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Journal ISSN
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Publisher
Universidad de Concepción
Abstract
En los centros galácticos activos (AGNs) podemos encontrar una diversidad de fenómenos físicos que emiten radiación electromagnética de formas muy distintas, las cuales son observables y diferenciales en distribuciones espectrales de energía (SEDs). Este trabajo se enfoca en modelar SEDs y estudiar sus formas, ocupando el código GRTRANS el cual utiliza una técnica de trazado de rayos para obtener intensidades mediante la ecuación de transferencia radiativa. En esta investigación se ocuparon los modelos esquemáticos HARM con un disco de acreción toroidal y rHARM3D con un disco de acreción semi-delgado. La radiación que se estudia es de sincrotrón térmica y no térmica variando componentes del AGN tales como la masa del agujero negro (M•), la razón de Eddington (λedd), la razón de temperaturas ion-electrón (Ti/Te), el exponente de la ley de potencia no térmica (P) y el ángulo de observación (α) que hay entre el observador y el eje perpendicular al plano del disco, con la finalidad de comprender como estos parámetros afectan la SED. También se estudian los mapas de luminosidad para cada uno de estas componentes a 22[GHz], 86[GHz], 230[GHz] y 345[GHz] para observar si existen dependencias en la frecuencia. Por último, se simula Sgr A* y se encuentra la distribución espectral de energía que mejor se ajuste a los datos. Esto se realizó encontrando la SED que tuviera una luminosidad bolométrica entre Lbol = (6,8−9,2)×1035[erg/s] para un estado quiesent” de Sgr A*. Como resultado encontramos que la razón de Eddington λedd = 1,5 × 10−9, la razón de temperatura ion-electrón Ti/Te = 3 y el índice de potencia P = 3,2 son los mejores valores para representar la SED de Sagitario A* considerando solo radiación de sincrotrón térmica y no térmica con un ángulo entre 20◦ y 40◦.
In active galactic nuclei (AGNs) a diversity of physical phenomena leading to the emission of electromagnetic radiation in very distinct forms can be found, which are observable and distinguishable via the spectral energy distributions (SEDs). This work focuses on modeling SEDs and studying their shapes, employing the GRTRANS code, which utilizes a ray-tracing technique to obtain intensities through the radiative transfer equation. In this research, schematic HARM models with a toroidal accretion disk and rHARM3D with a semi-thin accretion disk were utilized. We consider both thermal and non-thermal synchrotron radiation, varying AGN components such as the mass of the black hole (M•), the Eddington ratio (Ledd), the ion-electron temperature ratio (Ti/Te), the non-thermal power-law index (P), and the viewing angle (α) between the observer and the axis perpendicular to the disk plane, aiming to comprehend how these parameters affect the SED. Luminosity maps for each of these components at 22[GHz], 86[GHz], 230[GHz], and 345[GHz] are also studied to determine their frequency dependence. Finally, Sgr A* is simulated, and the spectral energy distribution that best fits the data is determined. This was done by finding the SED with a bolometric luminosity between Lbol = (6,8 − 9,2) × 1035[erg/s] for a "quiescent"state of Sgr A*. As a result, it was found that the Eddington ratio Ledd = 1,5 × 10−9, the ion-electron temperature ratio Ti/Te = 3, and the power index P = 3,2 are the best values to represent the SED of Sagittarius A* when considering thermal and non-thermal synchrotron radiation for angles between 20◦ and 40◦.
In active galactic nuclei (AGNs) a diversity of physical phenomena leading to the emission of electromagnetic radiation in very distinct forms can be found, which are observable and distinguishable via the spectral energy distributions (SEDs). This work focuses on modeling SEDs and studying their shapes, employing the GRTRANS code, which utilizes a ray-tracing technique to obtain intensities through the radiative transfer equation. In this research, schematic HARM models with a toroidal accretion disk and rHARM3D with a semi-thin accretion disk were utilized. We consider both thermal and non-thermal synchrotron radiation, varying AGN components such as the mass of the black hole (M•), the Eddington ratio (Ledd), the ion-electron temperature ratio (Ti/Te), the non-thermal power-law index (P), and the viewing angle (α) between the observer and the axis perpendicular to the disk plane, aiming to comprehend how these parameters affect the SED. Luminosity maps for each of these components at 22[GHz], 86[GHz], 230[GHz], and 345[GHz] are also studied to determine their frequency dependence. Finally, Sgr A* is simulated, and the spectral energy distribution that best fits the data is determined. This was done by finding the SED with a bolometric luminosity between Lbol = (6,8 − 9,2) × 1035[erg/s] for a "quiescent"state of Sgr A*. As a result, it was found that the Eddington ratio Ledd = 1,5 × 10−9, the ion-electron temperature ratio Ti/Te = 3, and the power index P = 3,2 are the best values to represent the SED of Sagittarius A* when considering thermal and non-thermal synchrotron radiation for angles between 20◦ and 40◦.
Description
Tesis presentada para optar al grado de Magíster en Ciencias con mención en Física.
Keywords
Agujeros negros