Abstract
We present a multifrequency analysis of the variability in the flat-spectrum radio quasar 3C 279 from 2008 to 2014. Our multiwavelength datasets range from 1mm to gamma-rays, with additional optical polarimetry. Cross-correlation analysis shows a significant correlation between the UV continuum emission, the optical and NIR bands, at a delay consistent with zero, implying co-spatial emission regions. We also find a correlation between the UV continuum and the 1 mm data, which implies that the dominant process in producing the UV continuum is synchrotron emission. Based on the behaviour of the gamma-ray light curve with respect to other bands, we identified three different activity periods. During period A we find a significant correlation at zero delay between the UV continuum and the gamma-rays, implying co-spatial emission regions which points towards synchrotron self-Compton as dominant gamma-ray emission mechanism. During period C we find a delay between the UV continuum and the gamma-rays, as well as a correlation at zero delay between X-rays and gamma-rays, both results implying that external inverse Compton is the dominant gamma-ray emission mechanism. This is the first time that observational evidence is presented for a change in the dominant gamma-ray emission mechanism in a blazar. During period B there are multiple flares in the bands from 1mm to UV, however, none of these show a counterpart in the gamma-rays band. We propose that this is caused by an increase in the gamma-ray opacity due to electron-positron pair production.
Highlights
During period A we find a significant correlation at zero delay between the UV continuum and the gamma-rays, implying co-spatial emission regions which points toward synchrotron self-Compton as dominant gamma-ray emission mechanism
During period C we find a delay between the UV continuum and the gamma-rays, as well as a correlation at zero delay between X-rays and gamma-rays, both results implying that external inverse Compton is the dominant gamma-ray emission mechanism
Blazars are known for their for their variability at all frequencies with a dominant component of non-thermal emission. They can be classified as Flat Spectrum Radio Quasars (FSRQ) or BL Lac type, depending on the visible features in their optical spectrum. 3C 279 is an FSRQ at z = 0.536, and was among the first quasars discovered to emit gamma-rays via observations by the Compton Gamma-Ray Observatory (Hartman et al, 1992)
Summary
Blazars are one class of jetted active galactic nuclei, with small viewing angle, the relativistic jet points almost directly to our line of sight (Urry and Padovani, 1995). Blazars are known for their for their variability at all frequencies with a dominant component of non-thermal emission They can be classified as Flat Spectrum Radio Quasars (FSRQ) or BL Lac type, depending on the visible features in their optical spectrum. 3C 279 is an FSRQ at z = 0.536, and was among the first quasars discovered to emit gamma-rays via observations by the Compton Gamma-Ray Observatory (Hartman et al, 1992). In this proceeding, we present the preliminary results of a multiwavelength variability study on the source 3C 279
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