Multi-Epoch Observations of the Redwing Excess in the Spectrum of 3C279

TL;DR

This study investigates the redwing excess in the quasar 3C 279's spectrum through multi-epoch observations, revealing that the excess is independent of observed properties and correlates with the broad emission line strength.

Contribution

It provides new insights into the redwing excess phenomenon in quasar spectra using multi-epoch data of 3C 279, emphasizing the need for further monitoring and spectropolarimetry.

Findings

Redwing excess is independent of optical, radio, or submm fluxes and polarizations.

The stronger the broad emission line, the larger the redwing flux fraction.

More monitoring and spectropolarimetry are necessary for understanding the phenomenon.

Abstract

It has been previously determined that there is a highly significant correlation between the spectral index from 10 GHz to 1350 $\AA$ and the amount of excess luminosity in the red wing of quasar CIV $\lambda$1549 broad emission lines (BELs). Ostensibly, the prominence of the red excess is associated with the radio jet emission mechanism and is most pronounced for lines of sight close to the jet axis. Studying the scant significant differences in the UV spectra of radio loud and radio quiet quasars might provide vital clues to the origin of the unknown process that creates powerful relativistic jets that appear in only about ten percent of quasars. In this study, the phenomenon is explored with multi-epoch observations of the MgII $\lambda$2798 broad line in 3C 279 which has one of the largest known redwing excesses in a quasar spectrum. The amount of excess that is detected appears to be independent of all directly observed optical continuum, radio or submm properties (fluxes or polarizations). The only trend that occurs in this sparse data is: the stronger the BEL, the larger the fraction of flux that resides in the redwing. It is concluded that more monitoring is needed and spectropolarimetry with a large telescope is essential during low states to understand more.