Using Multi-wavelength Correlations to Understand the Nearby structures in Strongly accreting AGN
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2025
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Abstract
Este trabajo explora los posibles cambios en las distintas estructuras que componen los núcleos galácticos activos (AGNs) a través de un enfoque multibanda. Se compiló una muestra de 63000 cuásares (QSOs) seleccionados ópticamente del Sloan Digital Sky Survey (SDSS) DR10, con corrimientos al rojo z ≤ 1. Esta muestra fue cruzada con las líneas de emisión [OIII] λ5007A provenientes de los espectros del SDSS-DR9, fotometría en el infrarrojo medio (MIR) del catálogo AllWISE y fotometría en rayos X del catálogo 3XMM-DR4, lo que dio lugar a múltiples sub- conjuntos de contrapartes. Analizamos las relaciones entre las luminosidades L(2keV ), L(12μm), L(2500A) y L(5007A), las cuales trazan diferentes componentes del AGN: el disco de acreción (UV), la corona (rayos X), el toro polvoriento (MIR) y la región de líneas angostas o cono de ionización ([OIII]). Estas correlaciones permiten investigar cómo varía la estructura del AGN en función de su luminosidad intrínseca, reflejando potencialmente cambios en parámetros como la masa del agujero negro, la tasa de acreción, la altura del toro y la geometría de ionización. Trabajos previos como Steffen et al. (2006) y Asmus et al. (2015) se utilizan como referencias clave para contextualizar y comparar nuestros resultados.Los múltiples subconjuntos se clasificaron en fuentes con “good photometry” (i.e., detected sources) y fuentes con “insufficient photometry” (i.e., upper limits). Estos límites superiores ayudan a acotar el espacio de parámetros y a revelar posibles sesgos observacionales. Construimos diagramas de luminosidad en los formatos L vs. L y L/L vs. L, aplicamos ajustes de Regresión Ortogonal por Distancias (ODR) a las fuentes detectadas. También se construyeron histogramas de estas distribuciones para calcular los anchos a mitad de altura (FWHM), y se utilizaron coeficientes de correlación de Pearson para cuantificar la fuerza de cada relación. Si bien las relaciones L vs. L muestran correlaciones sólidas y consistentes, las relaciones L/L vs. L permiten estudiar la eficiencia con la que distintos componentes del AGN reprocesan la radiación, revelando posibles variaciones estructurales con la luminosidad. Sin embargo, estas regresiones basadas en las tasas no siempre se alinean con las tendencias observadas en los gráficos L vs. L. La fuerte dependencia de la distancia presente en el eje X (logL) podría ampliar de forma engañosa la pendiente de las regresiones basadas en las tasas de luminosidad, lo que sugiere que las tendencias observadas en los diagramas L/L vs. L podrían deberse en gran parte a un efecto inducido por la distancia más que a una correlación intrínseca real. Nuestros resultados muestran una tendencia decreciente en L(12μm)/L(2500A) con el aumento de la luminosidad UV, en concordancia con las predicciones del modelo del toro en retroceso. Además, a medida que la luminosidad UV aumenta, el cono de ionización parece ampliarse y la luminosidad [OIII] aumenta en consecuencia. Sin embargo, dado que L([OIII]5007A) permanece sistemáticamente por debajo tanto de L(2500A) como de L(12μm), los datos sugieren que los conos de ionización no están completamente llenos de gas y polvo. En cambio, la emisión probablemente se origina en material concentrado a lo largo de las superficies de los conos, y no en todo su volumen. Estos hallazgos se ven respaldados por la tendencia adicional observada en L(12μm)/L([OIII]5007A) vs. L(2500A), y se confirman visualmente en la Figura 3.12, donde se ilustra el comportamiento geométrico combinado del toro y del cono de ionización. Se requiere una mejor resolución espacial y espectral en los rangos infrarrojo y óptico para poder resolver completamente estas estructuras internas de los AGNs y validar los escenarios propuestos.
This work explores the potential changes in the various components of AGNs through a multi-wavelength approach. We compiled a sample of 63,000 optically selected QSOs from the Sloan Digital Sky Survey (SDSS) DR10 with redshifts z ≤ 1. This sample was cross-matched with [OIII] λ5007A emission lines from SDSS-DR9 spectra, mid-infrared (MIR) photometry from the AllWISE catalog, and X-ray photometry from the 3XMM-DR4 catalog, resulting in multiple subsets of counterparts. We analyze the relationships between L(2keV ), L(12µm), L(2500A) and L(5007 A), i.e., luminosities tracing different AGN components: the accretion disk (UV), the corona (X-rays), the torus (MIR), and the ionization cone or narrow-line region (OIII). These correlations allow us to investigate how the AGN structure varies with intrinsic luminosity, potentially reflecting changes in parameters such as black hole mass, accretion rate, torus height, and ionization geometry.Previous works such as Steffen et al. (2006) and Asmus et al. (2015) serve as key references for contextualizing and comparing our results. The multiple subsamples were classified into sources with “good photometry” (i.e.,detected sources) and sources with ‘insufficient photometry” (i.e., upper limits). These upper limits help constrain the parameter space and reveal possible observational biases. We constructed luminosity diagrams in both L vs. L and L/L vs. L formats, and applied Orthogonal Distance Regression (ODR) fits to the detected sources. Histograms of these distributions were built to calculate FWHMs, and Pearson correlation coefficients were used to quantify the strength of each correlation. While the L vs. L relations show strong and consistent correlations, the L/L vs. L relations allow us to study the efficiency with which different components of the AGN reprocess radiation, revealing possible structural variations with luminosity. However, these ratio-based regressions do not always align with the trends seen in the L vs. L plots. The strong dependence on distance present in the X-axis (logL) may spuriously broaden the slope of the ratio-based regressions, suggesting that the observed trends in L/L vs. L could largely reflect a distance-driven effect rather than a true intrinsic correlation. Our results show a decreasing trend in L(12µm)/L(2500A) with increasing UV luminosity, consistent with the expectations of the receding torus model. Additionally, as UV luminosity increases, the ionization cone appears to widen, and the [OIII] luminosity rises accordingly. However, since L([OIII]5007A) remains consistently lower than both L(2500A) and L(12µm), the data suggest that the ionization cones are not entirely filled with emitting material. Instead, the emission likely arises from gas and dust concentrated along the surfaces of the cones, rather than uniformly filling their entire volume.These findings are supported by the additional trend observed in L(12µm)/L([OIII]5007A) vs. L(2500A), and visually confirmed in Figure 3.12, where the combined geometri- cal behavior of the torus and ionization cone is illustrated. Further spatial and spectral resolution in the infrared and optical regimes is necessary to fully resolve these internal AGN structures and validate the proposed scenarios
This work explores the potential changes in the various components of AGNs through a multi-wavelength approach. We compiled a sample of 63,000 optically selected QSOs from the Sloan Digital Sky Survey (SDSS) DR10 with redshifts z ≤ 1. This sample was cross-matched with [OIII] λ5007A emission lines from SDSS-DR9 spectra, mid-infrared (MIR) photometry from the AllWISE catalog, and X-ray photometry from the 3XMM-DR4 catalog, resulting in multiple subsets of counterparts. We analyze the relationships between L(2keV ), L(12µm), L(2500A) and L(5007 A), i.e., luminosities tracing different AGN components: the accretion disk (UV), the corona (X-rays), the torus (MIR), and the ionization cone or narrow-line region (OIII). These correlations allow us to investigate how the AGN structure varies with intrinsic luminosity, potentially reflecting changes in parameters such as black hole mass, accretion rate, torus height, and ionization geometry.Previous works such as Steffen et al. (2006) and Asmus et al. (2015) serve as key references for contextualizing and comparing our results. The multiple subsamples were classified into sources with “good photometry” (i.e.,detected sources) and sources with ‘insufficient photometry” (i.e., upper limits). These upper limits help constrain the parameter space and reveal possible observational biases. We constructed luminosity diagrams in both L vs. L and L/L vs. L formats, and applied Orthogonal Distance Regression (ODR) fits to the detected sources. Histograms of these distributions were built to calculate FWHMs, and Pearson correlation coefficients were used to quantify the strength of each correlation. While the L vs. L relations show strong and consistent correlations, the L/L vs. L relations allow us to study the efficiency with which different components of the AGN reprocess radiation, revealing possible structural variations with luminosity. However, these ratio-based regressions do not always align with the trends seen in the L vs. L plots. The strong dependence on distance present in the X-axis (logL) may spuriously broaden the slope of the ratio-based regressions, suggesting that the observed trends in L/L vs. L could largely reflect a distance-driven effect rather than a true intrinsic correlation. Our results show a decreasing trend in L(12µm)/L(2500A) with increasing UV luminosity, consistent with the expectations of the receding torus model. Additionally, as UV luminosity increases, the ionization cone appears to widen, and the [OIII] luminosity rises accordingly. However, since L([OIII]5007A) remains consistently lower than both L(2500A) and L(12µm), the data suggest that the ionization cones are not entirely filled with emitting material. Instead, the emission likely arises from gas and dust concentrated along the surfaces of the cones, rather than uniformly filling their entire volume.These findings are supported by the additional trend observed in L(12µm)/L([OIII]5007A) vs. L(2500A), and visually confirmed in Figure 3.12, where the combined geometri- cal behavior of the torus and ionization cone is illustrated. Further spatial and spectral resolution in the infrared and optical regimes is necessary to fully resolve these internal AGN structures and validate the proposed scenarios
Description
Tesis (Magíster en Astrofísica)--Pontificia Universidad Católica de Chile, 2025