Missing Seyfert Galaxies
Hrant M. Tovmassian1 and O. Yam2
1 Instituto Nacional de Astrofísica Óptica y Electrónica, México, Apdo. Postal 51 y 216, C.P. 72000, Puebla, Puebla, México (hrant@inaoep.mx).
2 Depto. de Ciencias, Universidad de Quintana Roo, Blvd. Bahía, 77019 Chetumal, Q. Roo, Mexico (oyam@uqroo.mx).
Received 2011 May 11 ]]> Accepted 2011 July 1
RESUMEN
El objetivo de este trabajo es la estimación del número de galaxias Seyfert faltantes debido a la ocultacion por el polvo del disco de las galaxias espirales. Comparamos la distribución de las inclinaciones de las galaxias anfitrionas de las Sy1s y Sy2s con la de la muestra de control de las galaxias espirales. Encontramos que el número relativo de galaxias Seyfert es mayor para las Seyfert vistas de frente, en las galaxias con i < 30°, y es menor en las galaxias muy inclinadas con i > 61° que en las galaxias espirales sin núcleos activos. Concluimos que la diferencia observada se debe a la absorción de los núcleos Seyfert en el disco de polvo de las galaxias inclinadas. Estimamos que las Seyfert faltantes son alrededor del 100% para las Syly y del 50% para las Sy2s.
ABSTRACT
The aim of this work is to estimate the number of Seyfert nuclei missing in catalogs due to obscuration by the dust disc in host spiral galaxies. We compared the distribution of inclinations of host galaxies of Sy1s and Sy2s with that of in control sample of spiral galaxies, and found that the relative number of Seyferts is higher in almost face–on galaxies with i < 30° and smaller in highly inclined, i > 61°, spiral galaxies without active nuclei. We conclude that the difference found is due to absorption of the Seyfert nuclei by the dust–disc of inclined galaxies. We estimate that about 100% and 50% of the observed Sy1s and Sy2s respectively are missing.
Key Words: galaxies: Seyfert.
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]]>ACKNOWLEDGMENTS
We are grateful to the referee for a careful reading of the paper and valuable suggestions for its improvement. HMT thanks the IPAC (Pasadena, CA, USA) for hospitality. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
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