Variability and evolution of the optical polarization of a sample of gamma-ray blazars

Otero-Santos, J.; Acosta-Pulido, J. A.; Becerra González, J.; Raiteri, C. M.; Carnerero, M. I.; Castro Segura, N.; González-Martín, O.; Luashvili, A.
Referencia bibliográfica

Monthly Notices of the Royal Astronomical Society

Fecha de publicación:
8
2023
Número de autores
8
Número de autores del IAC
3
Número de citas
5
Número de citas referidas
5
Descripción
We present a polarization variability analysis of a sample of 26 γ-ray blazars monitored by the Steward Observatory between 2008 and 2018 in the optical band. We investigate the properties and long-term variability of their optical polarization, searching for differences between blazar types. We observe that BL Lac objects are typically less polarized and less variable than flat spectrum radio quasars (FSRQs). Moreover, BL Lacs display a distribution of their polarization angle typically oriented in a preferential direction, contrary to the rather random distribution of FSRQs. For the latter blazar type, as well as those sources showing a bright stellar emission, we take into account the depolarizing effect introduced by the broad line region and the host galaxy on the measured polarization degree. In this sample, we also observe that BL Lacs present an uncorrelated evolution of the flux and the polarization. Contrary, FSRQs show a correlation before the depolarization correction, that is lost however after considering this effect. In addition, we study the behaviour of the polarization angle, searching for angle rotations in its long-term evolution. We derive that the FSRQs studied here show rotations more frequently than BL Lac objects by a factor ~1.5. During these periods, we also observe a systematic decrease of the polarization fraction, as well as a marginal flux increase, not significant however to connect rotations with optical flares. We interpret these results within the extended shock-in-jet scenario, able to explain the overall features observed here for the polarization of the blazar sample.
Proyectos relacionados
Project Image
Astrofísica de Partículas
El Grupo de Astrofísica de Partículas del IAC participa activamente en tres grandes colaboraciones internacionales de astrofísica de muy altas energías: AMS (Alpha Magnetic Spectrometer), los telescopios de radiación Cherenkov MAGIC I y II, y el Cherenkov Telescope Array (CTA). AMS es un detector de partículas diseñado para operar en el espacio, a
Ramón
García López
Imagen del Proyecto
Variabilidad en Núcleos Activos de Galaxias: Estudios Multifrecuencia
Los núcleos activos de galaxias (AGN por sus siglas en inglés) se caracterizan por una potente emisión proveniente de una región muy compacta (sólo pocos pcs) en el centro de la galaxia. Los "blazars" son una categoría de AGNs, caracterizados por mostrar una alta luminosidad en un amplio rango de frecuencia, desde radio a altas energías (rayos X y
José Antonio
Acosta Pulido