Cinemática y dinámica de gas ionizado en el núcleo de la galaxia M87.
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Date
2023
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Universidad de Concepción
Abstract
La medición de la masa del agujero negro en la galaxia M87, basada en su cinemática estelar, es el doble de la determinada mediante la cinemática del gas ionizado, con una discrepancia entre ambos mayor a 3σ. Para comprender mejor las razones del desacuerdo en las mediciones, es necesario delimitar mejor la morfología y cinemática del gas ionizado en las cercanías del núcleo. Los nuevos datos espectroscópicos de campo integral en el narrow field mode con óptica adaptativa, procedentes del instrumento Multi Unit Spectroscopic Explorer del Very Large Telescope, cubren en detalle la región nuclear de la galaxia, y son usados junto con un conjunto de datos en el wide field mode para modelar la morfología y cinemática de múltiples líneas de emisión de gas ionizado. Se usan mapas de momentos y diagramas de posición-velocidad para describir la cinemática del gas ionizado tanto a gran escala como en el núcleo de la galaxia; el ángulo de posición y la inclinación del disco rotante se fijan utilizando el programa Kinemetry; también se crean cubos de datos simulados, a través de un rango de masas de agujero negro e inclinaciones del disco, para obtener el modelo de mejor ajuste, mediante la parametrización de las diferencias de los mapas de velocidad residuales (observado menos simulado). Los resultados revelan complejidades en la cinemática del gas ionizado en el núcleo que no se habían observado en datos espectroscópicos anteriores más dispersos y superficiales: varios filamentos de gas ionizado, algunos con grandes velocidades, que pueden rastrearse hasta la esfera de influencia proyectada; un outflow bicónico parcialmente lleno, alineado con el chorro de la galaxia, con velocidades radiales de hasta 400 km s−1; y un disco de gas ionizado en rotación, con isófotas de velocidad torcidas. La complejidad de la morfología y de la cinemática en el núcleo impiden medir con precisión la masa del agujero negro a partir del gas ionizado. Los ajustes a la inclinación del disco en las cercanías del núcleo mediante Kinemetry, y las estadísticas de los mapas residuales de velocidad, favorecen una masa de agujero negro de alrededor de 6.0 × 109 M⊙ y un disco de inclinación de 25◦, en lugar de la masa de agujero negro de 3.5 ×109 M⊙ con un disco de 42◦ de inclinación propuestos en trabajos anteriores.
The black hole mass measurement of the galaxy M87, based on its stellar kinematics, is twice that determined via ionized gas kinematics, with the values disagreeing by more than 3σ. In order to gain insights into the reasons behind the disagreement between the measurements, it is needed to better constrain the morphology and kinematics of the ionized gas in the nuclear region. The new narrow field mode with adaptive optics integral field spectroscopic data, from the Multi Unit Spectroscopic Explorer instrument on the Very Large Telescope, covers in detail the nuclear region of the galaxy, and is used with a wide field mode data set to model the morphology and kinematics of multiple ionized gas emission lines. Moment maps and position-velocity diagrams are used to describe the ionized gas kinematics in both the large-scale and the galaxy nucleus; the position angle and inclination of the rotating disk are fixed using the program Kinemetry; simulated data cubes, across a range of black hole masses and disk inclinations, are created to obtain the best-fit model, by the parameterization of the differences of the residual (observed minus simulated) velocity maps. The results reveal complexities in the nuclear ionized gas kinematics not seen in earlier sparse and shallower spectroscopy: several ionized gas filaments, some with high flow velocities, which can be traced down into the projected sphere of influence; a partially filled biconical outflow, aligned with the jet, with radial velocities up to 400 km s−1; and a rotating ionized gas disk, with twisted velocity isophotes. The complexity of the nuclear morphology and kinematics precludes the measurement of an accurate black hole mass from the ionized gas kinematics. The fits to the subarcsecond disk inclinations from Kinemetry, and the statistics from the velocity residual maps, support a high black hole mass of about 6.0 × 109 M⊙ and low inclination disk of 25◦, rather than the previously proposed 3.5 × 109 M⊙ black hole mass with a 42◦ inclination disk.
The black hole mass measurement of the galaxy M87, based on its stellar kinematics, is twice that determined via ionized gas kinematics, with the values disagreeing by more than 3σ. In order to gain insights into the reasons behind the disagreement between the measurements, it is needed to better constrain the morphology and kinematics of the ionized gas in the nuclear region. The new narrow field mode with adaptive optics integral field spectroscopic data, from the Multi Unit Spectroscopic Explorer instrument on the Very Large Telescope, covers in detail the nuclear region of the galaxy, and is used with a wide field mode data set to model the morphology and kinematics of multiple ionized gas emission lines. Moment maps and position-velocity diagrams are used to describe the ionized gas kinematics in both the large-scale and the galaxy nucleus; the position angle and inclination of the rotating disk are fixed using the program Kinemetry; simulated data cubes, across a range of black hole masses and disk inclinations, are created to obtain the best-fit model, by the parameterization of the differences of the residual (observed minus simulated) velocity maps. The results reveal complexities in the nuclear ionized gas kinematics not seen in earlier sparse and shallower spectroscopy: several ionized gas filaments, some with high flow velocities, which can be traced down into the projected sphere of influence; a partially filled biconical outflow, aligned with the jet, with radial velocities up to 400 km s−1; and a rotating ionized gas disk, with twisted velocity isophotes. The complexity of the nuclear morphology and kinematics precludes the measurement of an accurate black hole mass from the ionized gas kinematics. The fits to the subarcsecond disk inclinations from Kinemetry, and the statistics from the velocity residual maps, support a high black hole mass of about 6.0 × 109 M⊙ and low inclination disk of 25◦, rather than the previously proposed 3.5 × 109 M⊙ black hole mass with a 42◦ inclination disk.
Description
Tesis presentada para optar al grado de Doctor en Ciencias Físicas.